well good evening. tonight I decided to do a talk kind of bringing us up to date
on the changes that have been occurring in the breeding avifauna on the Channel
Islands. this period of time from about 1950 to the present is a period showing
dramatic changes on the Channel Islands in terms of land use and in terms of
what's happening with the island habitats and those changes are having
some fairly significant effects on some of some of the native species and
introduced species that occur on the islands. and so without further ado we're
cut where I'm going to be covering a period from about the 1950s to the
present but the real focus of the changes is 1980 up to the present
because in 1980 there were several papers published in the second Channel
Island Symposium, one on the breeding land birds of the Channel Islands and
one on the breeding seabirds of the Channel Islands that form kind of a base
of what was known up to that point in terms of the populations of seabirds and
land birds on the Channel Islands. see if we can get it to move
oops oh there we go
got it okay now we got it technology
what did you do okay I see it okay got it oops. so the the things I'm going to
cover tonight first off is to kind of describe the factors that have been
affecting bird populations in in and around and on the Channel Islands. second
is to talk specifically about this period of herbivore
disturbance on the islands so when did herbivores get to each of the islands
and when were the last herbivores taken off the islands which sets the end date
and the beginning date for recovery of vegetative community structure on
islands. next is to kind of do an overview of how habitats have been
changing following the removal of herbivores on the island and then once
I've set that kind of background I'll go through by broad ecological groups
the changes that have occurred in in the on on on the eight Channel Islands in
each of the broad ecological groups again using 1980 for the land bird data and
1992 for the seabird data in terms of what was breeding on the islands in 1980 for
land birds, in 1992 for seabirds and I'll update the totals on the breeding avifauna
on each of the islands and then identify and talk a little bit about
how these changes in habitats are going to have positive effects for some
species and negative effects for other species so who are the winners and
losers as the habitats are changing. so again this this talk is focused not
just on Channel Islands National Park Islands- the five islands which which all
of you know make up the northern Channel Islands and Santa Barbara Island- but it
includes three the southern Channel Islands in this overall discussion
tonight. the data that's used for this presentation comes from a wide variety of
sources. in particular it's comes some some of the records are in
published papers, some of the data comes out of unpublished seabird contract
reports: nowadays in ebird, people post checklists to ebird of birds and
observations they've made on the islands and sometimes they record data of
breeding observations of birds also there's several US Fish and Wildlife
breeding bird surveys that have been conducted on on Santa Cruz Island and
then more intensive one on Santa Catalina and then the land bird point
count monitoring surveys the park has been doing for over 20 years on a number
of the park islands, and then finally unpublished photographs and
observational data that I've gotten ahold of, that people have submitted to me
either called me, sent me emails, sent me a letter, comes from a lot of sources. so
first off for seabirds the primary factors that seem to be affecting
breeding populations on whether they're increased increasing or decreasing or
disappearing from locations on the islands first and foremost is human
disturbance during the breeding season at a seabird colony. next would be
predation by native and introduced mammal mammals and avian predators. and
then pollution and contaminants we we know that DDT caused eggshell thinning
in in a number of species on the Channel Islands: brown pelicans, double-crested
cormorants, ashy storm petrels, peregrine falcons, and bald eagles and it
caused really dramatic population declines in the latter part of the 1960s
and early 1970s and so there were real constraints on on bird populations for
those species during that time window. and then more recently this nocturnal
light pollution from near shore commercial squid fisheries that have
been operating close to the islands during the breeding season have resulted
increased predation on some of the sea birds that nest and they come to their
nest sites at night when they're visiting the nest sites and they're
getting preyed on by owls and by other predators and so petrels and allison's
both are being affected by that. and then finally we know that for seabirds their
changes in their populations they cycle through time and
it oftentimes is linked to the relative abundance and success of given breeding
populations for certain species of sea birds in Southern California by
is really driven by oceanographic conditions and we know that El Nino and
La Nina events sometimes and Pacific Decadal Oscillations can affect the
distribution abundance of the preferred prey for the species that are breeding
there and if that preferred prey disappears from close proximity to the
islands during the breeding season or in the middle of the breeding season then
you see large population declines and loss of breeding success in populations.
so for land birds it's really driven by habitat so alteration of the terrestrial
habitats in the long term- overgrazing was the principal factor that's kind of
altered the land bird community structure on the Channel Islands for the
last 150 years. predation from native and introduced mammals and
avian predators and black rats are also a factor that affect breeding land birds.
and then more recently it's been the successional change that's occurring on
the Channel Islands as a result of as herbivores have been removed from the
islands and the islands are beginning to revegetate back into more native
habitats. in addition we have a whole series of conservation efforts that have
been contributing to the change in breeding land birds on the Channel
Islands. first and foremost would be the eradication of the introduced mammals on
the islands so the removal of all the feral herbivores, the eradication of
black rats on Anacapa Island 2001-2002, the eradication of feral cats on San Nicolas
Island, the active work that went on to reintroduce bald eagles back on and
bald eagles and peregrine falcons back onto the Channel Islands and to
reestablish them as dominant breeding birds on the island, the decline and
subsequent recovery of the northern Channel Islands fox populations the
period of decline and when foxes were out of the environment resulted in some
changes and some species coming and beginning to breed that had never been
recorded before on the islands, and then the removal of the Golden Eagles
on the northern Channel Islands was an active management program, and then
finally the intensive conservation efforts that had gone on for the individual
species that had declined like San Clemente Loggerhead Shrike and some of
the sea birds like Scripps' murrelet, Cassin's auklets and ashy storm petrels,
and then finally the principal thing that's occurring is this revegetation
and passive recovery of native habitats that's happening on the Channel Islands
following the removal of feral herbivores. so if we speak about the
herbivores there's a wide array of different types of grazing animals that
were introduced onto the islands. the first group is a group that I call the
livestock these are animals that man brought out and as part of ranching
operations on the islands and it's composed primarily of sheep, goats, pigs,
and cattle with sheep being the species that had the most dramatic effect on
terrestrial habitats on the islands in the latter part of the 1800s. but there's
there's there's another group of rewards called game animals which ranchers
introduced onto some of the islands in order to have stock that they could hunt
and have hunting programs on the islands and these are a few: Barbary sheep, mule deer,
snow deer and elk, bison on on Catalina Island so there's a wide array of those
kinds of introduced game species. so for the islands you can to figure out when
these things got to the islands and when they came off you can start with a whole
series of mining those historical photographs that had that are tied to
dates and locations and you can kind of document the presence of some of these
introduced animals from the historical photographic record but there's a wide
array of other sources that you can use- newspaper articles in the 1800s to legal
documents and land transfers that describe the resources that were on the
island- all of those feed into what's allowed us to kind of come up with those
beginning and end dates for when introduced mammals were on the island. so
for San Miguel Island herbivores were present starting in about 1851 and the
last herbivores were taken off in 1976 by the Park Service which was the
burros that were still on the island. for Santa Rosa Island herbivores got
there in about about 1844 and the last herbivore mule mule deer I think
the last of them came off I think in 2015 somewhere around there fairly
recently. Santa Cruz Island this 1855 painting by James Madison Alden shows
the ranch here on in the Central Valley and you can see they already had a
ranching operation going and this photograph from 1869 shows an active
ranch program and you can see habitats are already being decimated by the
grazing activity that was going on on the island even by 1869. Santa Barbara
Island herbivores we think sometime prior to 1863 and then by 1946 after
World War II sheep were the last of the sheep were finally taken off and then in
1981 the feral rabbits were finally removed from Santa Barbara Island. San
Nicolas Island it's 1856 for feral herbivores' introductions to the island and
that lasted until 1949 when the last of the sheep
were taken off of San Nicolas Island and the grazing operation was shut down by
the Navy. San Clemente Island it was 1853 to 1993
this is one of the pictures of how they they gathered up the sheep and
how they shipped them off the island. so if you put all of these end dates into a
table the top part speaks to rabbits, rats, and cats you can see first off look
for the Ps that are in yellow that are on the table that tells you that there's
still populations of those particular species present on that particular
island. so for black rats we still have them present on San Miguel Island, Santa
Catalina, and San Clemente so their presence is still impacting species of
land birds and sea birds on the islands where black rats still occur. they've
been eradicated from Anacapa Island in 2001-2002.
cats have been taken off all of the islands except for
Santa Catalina and San Clemente with the last removal happening on San Nicolas in
2010. below the yellow line as you look at this these are all the herbivores and
so again the only island that has any Ps left for populations that are still
present is Catalina and so the way I arrange these tables from here on out in
the talk as you look at this it's going to go north to south so as you as you
look at this it'll be San Miguel, Santa Rosa, Santa Cruz, Anacapa, Santa Barbara,
San Nicolas, Catalina, and San Clemente and I try to keep that organization so
you have an understanding of which island you're dealing with with the
respective data. anyway so we're left now on on the Channel Islands with only
Catalina Island still having some herbivores but the reason I did this was
because it's important to to understand when the islands were herbivore free,
when each island was free of herbivore impacts and so the earliest island to
be free of herbivore impacts was Anacapa Island see right here in 1937 and then
we go to 1946 for Santa Barbara Island, 1949 for San Nicolas, 1976 for San
Miguel, 1993 for San Clemente, 2006 with the removal of the last feral pigs on
Santa Cruz Island and then 2015 for Santa Rosa Island. these are the dates
when you no longer have that disturbance of herbivores affecting the terrestrial
habitat. so vegetations the kinds of vegetation changes that have occurred
following the removal of herbivores, first off there's been a reduction in
erosion and soil compaction. there's also been a reduction in the amount of
disturbed bare ground. there's been a reduction in the amount of introduced
annual grassland habitat and for that grassland habitat that remains there's
been an increase in the density of the vegetative cover of the grassland in
their remaining grassland and an increase in the amount of thatch buildup
in the grassland which is that dry residual matter that died the grass
dying each year is building up and building a thick
thatch layer. there's also been an increase in the native scrublands and
woodlands on the islands and so what this means is that that the mean over-
story cover of coastal sage scrub chaparral and Bishop pine woodlands on
Santa Cruz Island have been increasing and there's been an increasing in shrub
seedling regeneration, plant species richness, and basil sprouting to shrubs
and a development of this sub-shrub vegetation under woodlands and the
absence of any browse lines that had been created by herbivores in both the
scrublands and woodlands. there's also been a dramatic recovery in the emergent
freshwater marsh habitat and riparian habitats are starting to show
improvements as a result of the removal of grazing pressure in the understory. so we
have an increase in the overall cover of emergent marsh vegetation, an increase in
the canopy cover of riparian vegetation, and a reduction in the creek bank and
bed erosion. so now I'm going to show you a series of pictures- paired pictures-
over different time intervals so that you can actually see how these changes
have been occurring on the islands. so most of these are coming from Santa
Cruz Island, a few will be from Santa Rosa Island, but this is pictures
represents 28 year time span so when feral animals were present on Santa Cruz
Island this is what it looked like and here's 28 years later you can from the
same perspective the same location you can see the dramatic change in that
vegetative community structure. that change is driving changes in the in the
breeding avifauna on the Channel Islands so, oh one of the pictures didn't pop in
this shows 33 years later it shows what it looks like now I had another
picture up there that isn't showing up anyway dramatic change a lot more scrub
cover, density of grasses increased, this is the Central Valley on Santa Cruz
Island over a 37-year time window with the earliest period in 1971 when they
had grazing animals still present and sheep around and then you just fast
forward all the way through to 2008 really dramatic
in terms of the amount of vegetative cover on the island. this is the this is
out towards looking out to Christie Valley to the west again about a 30 year
time window in these three images from when when grazers were there oops so
when grazers were there and then 30 years later when they weren't. doesn't
look like these pictures loaded so not sure why. anyway this uh this picture
shows that dramatic change this was all bare ground along the slopes here and
it's filled in with vegetative cover and pine pines are starting to seed into it
pine forests expanding on Santa Cruz Island. this is Lobo Canyon on Santa Rosa
Island this is freshwater marsh that's developed in the floor of Lobo Canyon.
dramatic, I mean it's changing the understory the structure of the floor of
that Canyon and we now have Virginia Rails there is a year-round resident in
this habitat so we're pretty sure that they're breeding in this habitat now on
Santa Rosa Island. this is a 17-year time window for Old Ranch Canyon on Santa
Rosa Island when cattle were present in 1995 and then fast forward in 2012 and
you can see what's happened in in in the habitat I mean we have freshwater marsh
in here we have scrubland up on the flats and we have we no longer have this
stream bed erosion that's occurring and bank cutting that's happening. and then
on Santa Santa Rosa Island Windmill Canyon this is again a 17-year
comparison when cattle were present in 1995 you can see that there was almost
no willow woodland along the floor of the drainage and it was grassland on the
adjacent creek banks and look at 2012 it's a solid canopy of willow woodland
down the floor of the drainage now. so with that as a background I'm going to
speak to how how these different ecological groupings of birds have been
changing across the eight islands from 1980
to the present and the way in which I present the data in in these tables as
you look at this anything that's in yellow so like if if I've got a species
listed in yellow it means it's a new breeding record hadn't been recorded in
either of the 1980 publication or the 1992 publication for seabirds. if it
isn't in yellow it means that there's a population that had already been
recorded as breeding on at least one of the islands but if there's been a change
in the status of that species on some of the other islands then it will be noted
in yellow. so you can look at this fairly quickly and you can see here a whole
series of species that were introduced on to the islands during the period of
ranching years some of them were successful and became breeders like
Gambel's quail and chuckar we have chuckar on two of the islands San Nicholas
and San Clemente. and then some that fail they attempted to breed and then died
out and then more recently Indian peafowl and wild turkey were actively
eradicated by the Nature Conservancy on Santa Cruz Island so they've been
removed and the ranchers actually took quail from Catalina Island and
introduced them to Santa Cruz and Santa Rosa and we now have breeding
populations of Catalina California quail established on Santa Rosa and Santa Cruz
Islands. so you can see how those each of those are island specific changes that
are happening and then there have been introductions to lots of islands where
those introductions failed we have no indications that the birds that were
introduced survived and bred successfully and established the population for a
short period of time they seem to die out soon after they were introduced so
the fox has played Island foxes played a role probably in that removal. freshwater
marsh breeders this includes waterfowl, grebes, rails, and coots and a few land
birds so as we look at the water birds it's the larger islands where we have
breeding records for the water birds. we have a series of new breeding records
so as we look at the new breeding records as you can see gadwall, cinnamon teal, pied-
billed grebe, common gallinule, and common yellowthroat. gadwall a single breeding
record for Santa Rosa Island, cinnamon teal a single breeding record for San
Nicolas Island, pied-billed grebe a single record for
Catalina Island, common gallinule I actually found a historic egg set in a
museum collection back in Michigan that was collected on Catalina Island in the
early 1900s establishing the breeding presence of this species way back in the
early part of the 1900s on Catalina Island and then common yellowthroat we
have a recent documentation for breeding on at least three breeding attempts on
Santa Catalina and suggestions that they're also attempting to breed in
marsh habitat on Santa Cruz Island so again Virginia rail we've got them there
year-round now in Lobo Canyon in all likelihood they're breeding they're
difficult to find their nests so we don't have actual nests that have been
found and ruddy duck we've added another island to two breeding records for San Nick
and mallards we've got them breeding now on Santa Rosa and San
Nicolas and San Clemente Island so we've added a series of islands so it's all of
those larger islands that have man-made impoundments or small lakes that have
been built have created habitat that those waterfowl are now using. so if we
look at the raptors of all of the species of raptors we have three that
are new breeders to the islands- white-tailed kite has bred occasionally on
San Clemente Island, northern harrier documented breeding on on San Miguel
Island during that time period when island foxes had been removed into
captive breeding facilities on the islands you no longer had a terrestrial
carnivore in the environment and as a result the mouse populations exploded
and it allowed northern Harriers to create instate year-round and to actually
nest, they're ground nesters, and they bred for two to three years and then island
foxes was reintroduced and northern harriers would no longer breed on the island so
it's an in/out cycle for breeding. during that same time window we had evidence
observational data that suggested they were also breeding on three of the other
islands. Golden Eagles started breeding on Santa Cruz and Santa Rosa Islands
somewhere in the 1980s and that they were finally
trapped and relocated off the islands by 2006 so they no longer breed on these
two islands. Peregrine Falcons were reintroduced back onto the Channel
Islands and they're now breeding on all eight of the Channel Islands with San
Nicolas Island being a new island breeding record because they never been
recorded historically breeding on San Nick. American Kestrel's status hasn't changed
other than their abundance has changed as a breeder on some of the islands. Herons
and shorebirds we have two two two different species of herons recorded
breeding on the Channel Islands both of them are new and I'd list them as new
because all of the early literature for great great blue heron just says they
breed on the island but there's never been a documented case of the breeding
on the islands never published any observational data of confirmed nest or
eggs collected to actually confirm it. well we now have confirmed breeding
evidence for Santa Rosa, Santa Catalina and just recently San Clemente
and breeding behavior which is suggestive of breeding for Santa Santa
Cruz Island. I've documented a breeding of black-crowned night-herons now on
Catalina Island in and around Avalon which is the first time they bred on any
of the Channel Islands. black-necked stilt one breeding record for Santa Rosa
Island and then American oystercatchers which is an interesting species and I
have a picture down here showing a black oystercatcher and a hybrid American
oystercatcher and we have these hybrid American oystercatchers or suppose
supposed hybrids that are now pairing up with black oystercatchers
and we have evidence of them actively breeding as pairs on all of these
islands now and so they're hybridizing with the black oystercatcher. snowy
plovers the breeding status has changed on several of the islands so they used
to be a resident breeder on San Miguel and they haven't for the last few years
and they're an occasional breeder now in San Clemente Island. and then killdeer
we've added three additional islands with
with confirmed breeding evidence: San Miguel, San Nicolas, and San San Clemente
Island. storm petrels and pelicans and cormorants no new species breeding
records for the islands but we have a series of new breeding populations on
particular islands so as you look at the storm petrels ashy storm petrels now
confirmed breeding on Anacapa Island and San Clemente Island, Leach's storm
petrels recently confirmed breeding at Catalina Island and then we go down to
brown pelican it there they're breeding now on Santa Barbara Island and in 2011
they've bred on San Clemente Island. double-crested cormorants we have
breeding colonies now on Santa Rosa, Santa Cruz, San Nicolas and San Clemente
Island where in 1992 they hadn't been recorded at breeding on those islands.
Brandt's cormorants no real change in their overall breeding status. pelagic
cormorants two new breeding records for San Nicolas Island and recently one
breeding record for San Clemente Island and this is a picture of 2009 of pelagic
cormorants nesting on San Nicolas Island. gulls, terns, and alcids we do have
some new species records for the islands so California gull, Caspian Tern,
Guadalupe Murrelet, Rhinoceros Auklet those are all new breeding records for the
Channel Islands. California gull we had a single single pair that nested or
attempted to nest two years fairly recently on East Anacapa. Caspian terns
we have a single bird attempt to breed on San Nicolas Island recently and then
on Santa Catalina Island we have three different years that they were recorded
breeding on Bird Rock near the Isthmus on Catalina Island. common murres they
have bred off and on fairly recently on Prince Island it's a Miguel Island and
then rhinoceros Auklet same thing we've had some more recent breeding breeding
records for rhinoceros Auklet at San Miguel Island and then changes like
Scripps' murrelets they're now breeding on Anacapa,
Catalina, and San Clemente and Guadalupe Murrelet they split this into two
species so we now have new species they had been recorded breeding in the past on
Santa Barbara Island and then Cassin's Auklet since rats have been removed
they started breeding on Santa Barbara Island. so the other non-passerines this
would be the doves and the owls, spotted doves is a new breeding record for
Catalina Island. Rock Dove a couple of new breeding records we have Santa Rosa
Island and they used to breed on San Clemente but they don't anymore. Mourning
dove we have a new breeding record for Santa Barbara Island that hadn't been
reported before. barn owls we've confirmed breeding now on all of the
islands so we've added 3 additional islands for barn owls breeding there. one
new breeding record for burrowing owl on San Clemente. Short-eared owl they've nested
in the 1980s off and on on Santa Barbara Island and here's a picture of a nest
of short-eared owls in 1983 taken in 1983 by Charles Gross on on Santa Barbara Island. the
other non-passerines, common poorwill this is a species of goat sucker that's
been recorded calling and present in the late spring and summer months on three
of the largest islands but so far we have no firm evidence confirming
breeding so we don't know for certain that they're breeding there because
nobody's found any nestlings or eggs yet but that's one to be look for still.
Anna's hummingbirds they've definitely expanded their breeding range on the
islands we now have them breeding on San Miguel, Santa Rosa, San Nicolas, and San Clemente
and historically they were only breeding on Santa Cruz and Santa Catalina and
then acorn woodpecker a recent breeding records for acorn woodpeckers
on Santa Rosa Island so a new island for them breeding. so for the passerines
rather than go through all species of passerines I decided only to include in
the passerine tables those species that have showed some change in their
breeding status across the islands. if they haven't showed any breeding
change in terms of islands breeding on islands where they hadn't bred before
that I'm not including them in this overall listing so you're only going
to see the species where there's been changes. as you look at this list they're
a series of species here on the left that are in yellow: warbling vireo,
American crow, violet green swallow, and Canyon wren the ones with the question
mark means we don't have confirmed breeding evidence but we have
information suggestive that they're breeding there so I'm keeping them as ?
still. so those would be new species added to the island. very interesting
American crows have colonized in and around the Avalon area in Avalon Canyon
on Catalina Island they are now breeding on the island they had crows
American crows were really rare on any of the Channel Islands up until fairly
recently. so what else, Oh Black Phoebes we've added we've added a series of
islands with breeding records so you can see we added four islands with new
breeding records for black black Phoebes. loggerhead shrikes are really
interesting we've we've seen disappearances of breeding populations
on San Miguel, Anacapa, and Santa Barbara Island and declines in their population
on Santa Cruz Island and Catalina Island so this change in open grassland habitat
the scrubland is not as beneficial for loggerhead shrikes. and then horned larks
they've disappeared as a breeder on Santa Barbara Island and bushtits have
now showed up as a year-round resident on Santa Rosa Island and in all likelihood
are breeding now on Santa Rosa Island so that's a new breeder for for Santa Rosa
Island. and Canyon wrens we have them year-round on Santa Cruz Island now in
the canyons on the north side of the island and we don't have confirmed
breeding evidence in the sense of having nest, eggs or fledglings being fed
by adults but the fact that they're there year-round and singing on
territory suggested that there is an established population of canyon wrens now
on Santa Cruz Island. we've added breeding breeding status for blue-gray gnat
catchers now on Catalina Island and Swainson's thrushes now on Catalina
Island. so in this group of passerines we've got American Robin, common
yellowthroat, black-chinned sparrow, and grasshopper
sparrow all new species never been recorded breeding on any of the Channel
Islands in the past. American Robin are now breeding on Santa Cruz Island and we
have evidence suggestive that they're breeding also in small numbers on
Catalina Island. common yellowthroat again breeding on Catalina and
suggestive evidence that they're breeding on Santa Cruz. One breeding record for black-
chinned sparrow on San Clemente and then really interesting is the grasshopper
sparrows confirmed breeding on San Clemente Island and suggestive evidence
of breeding on the three northern Channel Islands again after herbivores
were taken off the islands and the grasslands thickened up got really thick
thatch layers and weren't being grazed grasshopper sparrows came in and started
breeding. and then a really interesting one that showed up has been song
sparrow on Anacapa Island so this is a species never been recorded breeding
on Anacapa Island in the past and it's now has confirmed evidence of breeding
on Anacapa Island after the rats had been eradicated so this is one of those
benefits from the removal of rats and we think there showing up evidence
that suggested they may be breeding on on Catalina Island also. and then
dark-eyed juncos are breeding now on Santa Cruz Island. and then the last
birds with changes we've got suggestive evidence for black-headed grosbeaks on
Catalina Island. Lazuli buntings is a new breeder to the Channel Islands
we've got them breeding on San Clemente Island two confirmed breeding records one
confirmed for Santa Rosa and suggestive evidence for their breeding on Santa
Cruz and Catalina and then hooded orioles have been recorded breeding on
at the ranch on Santa Cruz Island. and then the only change in house finches
has been change in abundance we have they disappeared as a breeder on Santa
Rosa Island and their numbers are declining on some of the other islands
and so that those are the main changes that have been occurring. now what I'd
like to do is is kind of give you the numbers the total numbers so as we look
at total numbers of birds recorded breeding what I did is I divided this
into two two categories these small columns on the bottom are all of those
introduced species that were actively introduced by man or were introduced
into North America and got to the islands on their own accord and
established breeding. I decided to tease those out separately from all of the
other native species of birds that have been recorded breeding on the island so
that the total is represented here are only for those native species and
includes everything from waterfowl and seabirds, shorebirds, you know, raptors
it's everything all all birds so you can see right off Santa Cruz Island has the
largest number of species that have been recorded breeding on that island and
that's 70 species not including the introduced species. and the fewest number
of species recorded are for San Nicolas Island with 28 species. on this plot is
the size of the island so you can see the relative size of the island and you
can see that all of the larger islands in general have the most species
breeding and the smaller islands tend to have the fewest number of species
basically. Santa Rosa Island has fewer species than it should for its size it
should be further up somewhere up in here for its size whereas Catalina
Island has more species breeding than for its overall size so those are the
broad trends. if you break it out by ecological groupings so you organize it
by passerine birds or the perching birds which would be you know fly catchers to
sparrows to finches or non-passerines-raptors, shorebirds, herons, seabirds, or
fresh water birds this is how the numbers break out so you can see kind of
passerines on all of the islands make up in general the largest largest
grouping of birds of species are represented in the passer forming and
then the next would be down in here which are the seabirds and I put the
total numbers through each of those categories so in purple are all the
seabirds and you can see high numbers of breeding seabirds on the smallest island
compared to high numbers of passerines breeding on the largest
islands and then these are all the raptors that would be the next group and
again the same thing larger islands in general tend to have the larger number
of species breeding. so to summarize this you know what species are benefiting and
what species are not benefiting from this passive vegetation change that's
occurring on the islands now now that feral herbivores have been removed? when
grasslands and bare ground decline there are a series of species that are
adversely affected and this is that list of species so American oystercatcher,
mourning dove, burrowing owl, horned lark, loggerhead Shrike, European Starling, and
house finch all of those species are showing population declines on the
islands as grasslands are declining but there are species that are showing
positive effects for changes in that grassland community structure and two of
these I've got pictures of just to point out grasshopper sparrows here which is
an obligate nester in grassland habitat but when the islands were being grazed
it was being heavily grazed so we had very very short grass cropped grassland
with little if any thatch left over which didn't provide the kind of structural
condition of the habitat that would allow grasshopper sparrows to build
their nests in the in the grass on the ground and survive predation from the
predators that were out. get rid of herbivores the grass grows up, nothing
eats it, it dies, it falls over, next year the grass goes up, it dies, it falls over, it
builds up over time it creates a thick thatch very dense grassland community
structure initially and lo and behold within within two years grasshopper
sparrows established breeding on on on the island under those conditions.
fast-forward 20 years that grasslands transforming into the scrubland so shrub
species are beginning to grow in that grassland and beginning to spread and
the canopies of those shrubs are beginning to overlap and they're
beginning to shade out the grass underneath and so the structure of the grassland is
changing into a scrub one. grasshopper sparrows are going to be limited to only
a few areas of grassland habitats that are sustained as dense grass- ungrazed
grassland- and they're going to disappear from those broader areas where
scrublands have taken over. Rufous-crowned sparrows which is a an endemic
subspecies of Rufous-crowned found on Santa Cruz and Anacapa Island. on Santa
Cruz Island their populations have increased in both their distribution and
their relative abundance on Santa Cruz Island following the removal of
herbivores and the reason for that is that the scrub habitat started to
regenerate, grassland began to mix in underneath the canopy of that scrub
scrub land but there was still some openness in the scrubland habitat on the
slopes and that was really prime habitat for Rufous-crowned sparrows and their
populations took advantage of it and they they grew and expanded on Santa
Cruz Island. now as that habitat is transitioning into complete scrub
dominated community with little if any grass in in the habitat or grass open
areas of grassland habitat the Rofous- crowned sparrow populations are going to
be dying back in terms of overall abundance on the islands on Santa Cruz
Island they're going to be more isolated to those particular slopes that
still maintain that kind of structural complexity of the vegetation. so if
scrublands increase here are a few of the species that are going to be
benefiting from this increase in scrubland habitat on the island: Bewick's
Wrens, spotted towhees, again Rufous-crowned sparrows at least on Santa Cruz Island
and then Lazuli buntings and lo and behold we've recorded new breeding
records this a new species breeding on the islands hadn't been breeding there
before probably because it didn't have enough of the good scrubland habitat.
alright. as woodlands increase so as oak woodlands and pine forests are
increasing on the islands in the absence of grazing those species that prefer the
tree canopy part of that habitat their populations are going to benefit from
that increase. so all of these things: Allen's hummingbird, acorn woodpecker, scrub
jay, all of these guys in this upper part are going to be benefiting from that
change in the vegetation structure that tree canopy that's created. but in
association with that it's not just the canopy that's changing its that
understory habitat underneath the woodlands that's changing really
dramatically. when pigs were present it was new it was it was rototilled
underneath that habitat in the woodlands and so you had this kind of
bare ground all tilled up you didn't have any sub-shrubs in that habitat, there
wasn't seedling regeneration taking place and for these near-ground and
ground-nesters they were impacted by that because their breeding habitat was
had declined. now that that has disappeared that that impact and we have
sub-shrubs and herbaceous vegetation growing in in the understory of the
woodlands, species like orange-crowned Warbler, song sparrow, dark-eyed junco and
black-headed grosbeak all of those are going to benefit from that change in
that sub-shrub sub-shrub structure underneath the dense woodland habitat
and lo and behold we got dark-eyed juncos breeding now in Santa Cruz Island
where they hadn't been reported breeding before. song sparrows breeding on
Anacapa Island where they hadn't been recorded breeding before. now for
freshwater wetlands again it that development of freshwater marsh habitat
around the margins of ponds and lakes and along the stream courses on the
larger drainages on the islands is generating habitat that these freshwater
breeders like and as a result they're coming in and starting to breed on some
of the islands and we've we've documented breeding now we're pretty
sure Virginia rail is breeding on Santa Rosa Island, and we've added American
coot breeding records to several of the islands, mallards to three or four of
the islands, ruddy duck to one of the islands, common yellowthroat to two of
the islands, again song sparrow to Anacapa Island and we think to Catalina
Island so there's been we're already seeing those changes happen is because
that the habitat is there. if you get the habitat those species when they're
migrating across the island are going to find the habitat and if they find it
suitable they're going to they're going to live in it. as the riparian woodlands
begin to regenerate there are an additional series of species that are
going to benefit from that tree canopy habitat and these are just a few of them:
Northern Flicker, ash-throated flycatcher, warbling vireo, and Swainson's thrush
are species that I expect are going to benefit from that kind
of change in the woodland habitat. so in conclusion over the last 150 years we've
been able to document 105 species of birds that are nested on one
or more of the islands at one point in time, they're not all nesting there today,
but at over that 150-year time window we have 105 species that we have records
for now as having bred on the islands. from the 1980s up to the present we have
27 species that are new first time breeders for the Channel Islands from
this additional kind of harvesting of these records and eight that are that
would be new they're suspected of breeding on the islands we still need
better evidence to confirm them as breeding. there have been a total of
67 new island specific breeding records that's where a species hadn't
been recorded breeding on an individual Island before but they're breeding there
now so 67 separate little changes in breeding status on the
islands and then 59 Island specific breeding status changes that means where
it had been listed as questionable as breeding or as occasional they may now
be common or a resident breeder so those breeding status changes are also
occurring on quite a few of the islands. three species have been eradicated from
the islands including wild turkey, Indian peafowl, and golden eagle. we have two
native raptors that have been reintroduced back onto the island: bald
eagle and peregrine falcons. bald eagles are breeding on all but three of the
islands now and peregrine falcons are breeding on all eight of the islands. and
then we have five species that this change in habitat following the removal
of herbivores is resulting in some changes in breeding status for these
five species so we have loggerhead shrikes have disappeared as breeders on
San Miguel, Anacapa, and Santa Barbara Island and declined on two of the other
islands. horned larks have disappeared as a breeder on Anacapa. common Raven has
disappeared as a breeder on Santa Barbara and San Nicolas Island. and
European starlings no longer breed on San Miguel, Anacapa or Santa Barbara
Island. and house finches no longer breed on Santa Barbara Island. so these are
during the question period these are some pictures that have been
sent to me of confirmed breeding records or evidence that confirms a breeding
occurrence of given species on an island where they had bred before so as you as
you look at these images we've got pelagic cormorant up here on the left on
San Nicolas Island, Anna's hummingbird feeding a nestling here, dark-eyed
juncos an adult with a juvenile right here in 2013, the first breeding record
for a killdeer on San Clemente Island here's a chick, here's an acorn storage
tree and then there are actually nest holes in this Ironwood tree on Santa Rosa
Island, and then of course Mallard on San Nicolas Island in 2010. so I'll open it
to questions a lot of changes going on on the islands and they're going to
continue to be a lot of changes as these islands are changing in terms of their
habitats and then as the islands change as a result of the effects of global
warming we at this point we don't know how that also is going to be affecting
changes in breeding status on the number of new species on the islands but it's
an exciting time to be around as a as a biologist working on the islands because
when I started 40 years ago working out on the Channel Islands these big islands
were all ranches and they had grazing animals all over them and so my
understanding of the fauna of the islands at that time was based on that
that work that took place when it was an actively being managed as a ranching
operation and the habitats had all been changed. now fast-forward 40 years later
and we're seeing these dramatic changes in vegetative community structure which
are really driving changes in the faunal composition on each of these
islands as a result of the removal of those herbivores. so yeah it's exciting
time to be around. kind of watch that watch and see how quickly it's happening
on that transition. ok my question is regarding the golden eagle yes one of
the slides showed that they were taken off of Santa Rosa and Santa Cruz. yeah
they were they were trapped and relocated into the Great Basin.
yeah that was the question where did they where do they end up? the bulk of the
animals the adults- the paired adults- were trapped and taken up north of Reno
and released on east of the Sierra Nevada and Cascade Range and then they were
they had some of them satellite tagged some of them radio tagged and they followed
tracks of these things they moved all up through the Great Basin up into Idaho and
Montana and Utah and wandered around feeding on jack rabbits which is their you know
preferred prey not Island foxes. so 2006 was when the last adult breeding pair of
golden eagles was trapped and relocated off the island of Santa Cruz. yes my
my question is the shorebirds or sea birds that that breed on the islands we
I've heard that we wouldn't have very many of them along the coast if it
wasn't for our Channel Islands is it the seabirds or the shorebirds that that
we're speaking? seabirds. seabirds? yeah yeah the the diversity and the abundance
of the seabirds that breed on the California Channel Islands is
significant for seabird breeding populations along the west coast of
North America. thank you. I mean we have some of the largest concentrations
of species of breeding species on it Islands like Prince Island on San Miguel
and Santa Barbara Island of any place along the west coast in North America. I
have a question, is most of the birds that are on the islands are they from
migratory birds that are landing there and then creating populations or are
there any endemic species? there are a variety well all of this all of the
birds that have gotten to the island other than the game birds that man
carried out there and released in order to have peacocks and turkeys and quail
the hunt on the islands got there on their own accord so even things like
European Starling and house sparrows which are non-native species that got
that were introduced into North America they eventually found their way and flew
out and landed on on some of the islands and established breeding population all
of the other birds have gotten there some of which stayed and established
breeding populations and didn't migrate off the islands
and over millennia evolution began selecting for unique morphological and
genetic characteristics within their populations from island to island as you
move across that chain depending on how long of a period of isolation they had
in each island population so there are about eight or ten species that show
endemism there's one endemic species the island scrub jay found only on Santa
Cruz Island today but I have fossil evidence for it now on San Miguel Island
and Santa Rosa Island in the past and then the rest of them are all either
near endemics where we have a population that breeds in a small area on the
mainland but then is it's found on a series of the Channel Islands or the
length of time that they've been isolated hasn't created enough real
strong genetic divergence between the adjacent mainland populations so weakly
diverged in terms of their morphology and their genetics so the thing that's
really revolutionising our understanding of the evolution of this that resident
breeding fauna avifauna the endemic breeding avifauna of the islands is is
the mitochondrial DNA work that's going on now where they can really look at the
length of time that populations emerge from each other, how each island
population is related to each other, how long they've been separated, how long
they the island populations have been separated from mainland populations so
we get a much better clearer understanding of how evolution has been changing and
modifying those island population. so an example would be a woman recently
finished her master's thesis doing a study on genetics of spotted towhees on
that channel islands and they breed on Santa Cruz Island, Santa Rosa Island,
Catalina Island, and San Clemente Island. they're extinct on San Clemente Island
they died out by the 1960s but all of the other islands they're still present.
when she did the mitochondrial DNA analysis each of those populations
showed enough genetic divergence to warrant full species recognition so
we're going from a single species and only two subspecies recognized for the
island to potentially four unique endemic subspecies or potentially full
species recognition for several of those on the Channel Islands and we're going
to see that in a number of other species as these genetic studies get underway
and they're they're they cover more in the islands where those species occur so
it's pretty exciting to kind of see that kind of stuff going on. I wanted
to ask how much has habitat restoring habitat planting on the island affected
the bird populations and have certain have you had more success in certain
restoration? I'm not that close to the to the botanical work that's been taking
place and the revegetation. I'm looking at the kind of the broad scale picture of
what's happening on an island as opposed to the narrow picture of a particular area
that's doing active management in, like on Anacapa Island East Anacapa Island
they removed all of the the ice plant and have revegetated with native plant
species. I don't know data that's been taken before the ice plant was removed
and then post after that habitat develops to kind of identify what
species have benefited from that change of that introduced you're getting rid of
that introduced ice plant but there are cases where there's been that really
active management going on in order to regenerate habitat. Santa Barbara Islands
a good example, like Scorpion Rock is another good example we've been doing a
lot of revegetation work on Scorpion Rock to create the kind of natural
vegetative community structure that provides better protection for the burrow
nesting seabirds that visit their burrow nest sites at night to reduce the
predation that owls would have on them. they've under revegetated top of that
Island so those things are important but across the overall Island there hasn't
been a lot of active work in trying to manage that change from grassland to
scrubland it's happening it's taking place it's a natural progression that's
happening and it's going to continue to happen. yeah. I have a quick question
about albatross I understand albatross is a come from Hawaii to our Islands is
this but I didn't see any of it on yours? we have no breeding
evidence for either of the three species of albatrosses that are found in the North
Pacific on any of the Channel Islands however we have a lot of evidence out of
the archaeological record of the occurrence of short-tailed albatross
skeletal material in archaeological context suggesting the Native Americans
were hunting them and harvesting the birds when they were in close to the
islands and so that's a species that gets close to the islands. the other two
species of albatross albatross, the laysan and black-footed albatross are primarily
open ocean species of albatross like the black-footed it nests in the Central
Pacific on the on the outer of the Hawaiian Islands and during the breeding
season those birds transit all the way to the west west coast of North America,
feed along the escarpment of the continental shelf escarpment where it
drops off into deep ocean, they feed along that escarpment, turn around fly
back, feed their young, turn around fly back to the west coast, feed, feed,
feed feed their young they do that all through the breeding season whereas
the laysan albatrosses in Hawaii they don't they don't go that direction they
go north and they go up to the convergence zone between the cold arctic
waters and the subtropical waters which are about 1,500 or 2,000 miles north of the
Hawaiian Islands and they fly straight north feed around there come back feed
their young fly back feed around there come back and they do that all through
the breeding season so these these are birds that are coming thousands of miles
of ocean on a weekly basis just to feed their young it's pretty phenomenal. My
I can't tell if this is on or not but my question is do you have permanent observers on the
islands? no the only island that has relatively good coverage in terms of
breeding observation on a continual basis is San Clemente Island and the
reason for that is they have a series of research scientists that are hired to
manage and work on the loggerhead Shrike recovery program and bell the San
Clemente bell sage sparrow recovery program and you know several other
species of birds and so they're there 24/7 all year long and they
got into birding on their free time and those that those records were being
entered it initially into an Excel database which I was they shared with me and
I was able to kind of harvest information out of that Excel database
and then subsequently a lot of those individuals are posting their checklists
daily up to eBird so I can go you can go into eBird and you can see what the most
recent sightings have been for San Clemente Island or for a particular
species on San Clemente Island and so some of that breeding evidence is coming
out of those checklists that get posted.
you were talking about albatross flying these great miles and miles,
albatross I think of as big very strong birds but what how do these
little tiny guys get the 26 miles out to the islands to start a breeding colony,
how do they do that? well a lot of a lot of these land birds the ones that breed
to the north of us and into the interior that have to get out of those those
areas during the winter and they have to migrate into warmer climate areas
they're migrating on the west coast of North America they're migrating
oftentimes in a north-south direction or they come to the coast and then migrate
north south down the coast of California well if you look at a map of California
the map of California comes down kind of north-south and then it hits Point
Conception and goes zheeew and then drops back to a north-south by northern
Baja California. well there's the Southern California bite where that
changes if you're flying north-south down along the coast and you stay north-
south you go right over the Channel Islands and then BOOM you're on to
northern Baja California if you stay in that north-south transit and you have a
series of these islands to be able to stop on while you're passing over the
water. on the northward migration is very different because they're not
they're kind of moving their way up through Mexico into into western North
America through a very a variety of routes and they don't have a direct
north-south route that will take them out to the islands and so you get a
different kind of migratory pattern of birds as they move when they're moving
north-south as they're coming to get up to their breeding areas so. well we have
some banded birds some birds that were banded on San Nicolas Island like
white-crowned sparrows that came back to San Nicolas Island 51 miles offshore
three winters in a row and these are birds that likely bred all the way up
in northern Canada or Alaska so they migrated all the way down along the west
coast of North America wintered on San Nicolas Island and migrated all way
back up and bred came all the way back down and so there's there's a little bit
of evidence like that birds that have been banded and recaptured indicating that
they're showing these really long distance movements and this you know
wanting to stay on an island during the winter to winter they find the habitats.
We have time for one more question. in your research have you seen any
indication of ingesting plastic? in the albatrosses I've seen plastic and in a
few of the other seabirds when I worked on them for specimens going into the
collection but albatrosses in general are picking up bits and pieces of
plastic that are floating. I haven't gotten fresh specimens from around the
islands these are albatrosses that are coming out of the North Pacific out of
off the Aleutian Islands and out in the Bering Sea that are caught getting
caught in longline fisheries and out of those incidental fisheries caught birds
there they're actually having ingested plastics from foraging out you know
around that upper rim of the Pacific. I got a little bit of plastic out of a
short-tailed albatross I worked on that washed in dead at Morro Bay but that's
a bird that it it left the breeding colony on the island southeast of Japan
a month and a half before it showed up dead on Morro Bay so it transited from
southeast of Japan all the way up along Asia to the Aleutians around the
Aleutians all the way down the west coast of North America to Morro Bay, this
juvenile before he showed up dead. so we have one last question this is very
interesting. thank you it's regarding the Santa Cruz Island Jay and I recently
heard that they that they're starting to differentiate a
little bit between the different habitats that their beak is changing is
that true? yeah they've found this micro geographic variation within the
population on Santa Cruz Island between the pine forest habitats and oak
woodland habitats from the east east end of the island to the west end of the
island and so by live capturing and taking a suite of measurements on the
bills and of banded birds so they could kind of monitor the home range size of
where those birds were hanging out they were able to gather data that documented
morphological differentiation between the populations that were in one one
type of habitat pine forests in one area of the island compared to another
habitat that was in another area of the island away from it and so what really
one of the first cases of a large vertebrate that they found evidence to
actually show active evolution taking place and that's a woman did her PhD
thesis on this work. and with all of the pine pine trees dying that's have you
seen any effect with the birds in the terrible loss of all the pines on
Santa Cruz? there's going to be a decline in the species that benefit from the
pine canopy habitat that the canopy part of the structure of that habitat but the
sub shrub understory habitat of that forest is going to change its going to
fill its filling in with denser scrub scrub cover that's going to benefit a
whole suite of species that like that scrub covered habitat and you're going
to get seedling regeneration starting for pines coming up through that and
over time it'll it'll re-canopy over the scrub and kind of have this
kind of die-back and the scrub cover underneath that canopy so it's a
progression and you're going to see that cyclical change in these habitats.
whether this decline in the pine forests on Santa Cruz Island is going to be long-
term and that is going to be kept in place by increasing temperatures from
climate change as we look out into the future that's yet to be seen. I mean if
you had a fire going at right now and burned it you'd see a real dramatic
change in the overall structure and you can see a hell of a lot of seedling
regeneration in that habitat taking place because that's what it's
adapted for you see a lot of new growth. okay thanks thank you everyone
you