As the cold of winter gradually gave way to the warmth of spring this year, the restored Giacomini Wetlands became home to a whole new group of animals, many of whom are only rare visitors to the Tomales Bay-Point Reyes area.

With reintroduction of the tides to the former dairy ranch has come a slow conversion of pastureland to marsh. In the first spring after restoration, Atriplex triangularis seedlings—a brackish marsh plant species with triangular-shaped leaves—began to carpet many of the restored areas. In some of the more tidal areas, tiny pickleweed (Sarcocornia pacifica) seedlings also began to emerge.

To help us follow this transition from dairy ranch to coastal wetland, local wildlife biologists Jules Evens, Mary Anne Flett, Seth Bunnell, and Rich Stallcup of Avocet Research Associates conducted a series of spring breeding bird surveys. Avocet also conducted baseline surveys of the Giacomini Ranch prior to restoration and has tracked bird use of the Giacomini Ranch and surrounding area for several decades.

White pelicans

Evens and his colleagues found that the Giacomini Wetlands continues to be home to many species that were common prior to and even during construction. White-tailed kites (Elanus leucurus) hover over the dormant grasslands, looking for rodents. Long-legged waders concentrate in impressive numbers along the channel bank—one March morning, more than 50 Great egrets (Casmerodius albus) and a dozen Snowy egrets (Egretta thula) and Great blue herons (Ardea herodias) were observed roosted along the main channel. As many as 130 White pelicans (Pelecanus erythrorhynchos) congregated in open water areas in the northern portion of the East Pasture, up from 40 last year, said Louis Jaffe, a local resident who has been observing bird use in the wetlands. White pelicans are thought to be opportunistic fish-eaters, but, interestingly, a large flock foraging in the wetland panne in early June was consuming filamentous algae (J. Evens, pers. obs.)

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But they were new visitors, too. Spring is the time for breeding, and many neotropical migrants or birds that may migrate from as far as South and Central America flock to this area to establish nests. During spring, Marin hosts as many as 150 species of breeding birds, and most of these occur on the coast (ARA et al. 2002). Tomales Bay cannot compete with San Francisco Bay in terms of sheer numbers, but Tomales Bay supports higher densities of many species (J. Kelly, ACR, pers. comm.) and accounts for a large proportion of many species' statewide population numbers. Tomales Bay is one of only three sites along the Pacific Flyway that support more than 100 Red knots (Calidris canutus) during spring migration (C. Hickey, PRBO, pers. comm.). Ten of the 17 Partners-in-Flight Riparian Focal Species breed in the Point Reyes region (C. Hickey, PRBO, pers. comm.). A large factor in the avian diversity found in Point Reyes comes from rare or extremely rare species, which account for nearly one-third of species observed (Evens 2008).

Even prior to restoration, the Giacomini Ranch and surrounding area supported impressive breeding bird activity. The large freshwater marsh and adjacent riparian habitat in the West Pasture adjacent to Sir Francis Drake Boulevard was one of the breeding hotspots, supporting Saltmarsh common yellowthroat (Geothlypis trichas var. sinuosa, former FSC, CSC), Virginia rail (Rallus limicola), Song sparrow (Melospiza melodia), Marsh wren (Cistothorus palustris), Brewer’s Blackbird (Euphagus cyanocephalus), and other marsh-riparian associates (ARA et al. 2002). Two other areas that also attracted high number of breeding birds were the riparian-grassland habitats of Green Bridge County Park and the riparian-mesic coastal scrub habitats found on some portions of the Point Reyes Mesa bluff (ARA et al. 2002). Yellow warbler (Dendroica petechia brewsteri, CSC) has been observed breeding in the Green Bridge County park area and near Inverness Park and is a common fall migrant through riparian corridor (ARA et al. 2002). During baseline surveys, the Point Reyes Mesa bluff attracted a diverse array of the breeding birds observed in the area during spring, including species such as Swainson’s thrush (Catharus ustulatus oedicus, CSC), Bewick's wren (Thryomanes bewickii, CSC), Wilson’s warbler (Wilsonia pusilla), Warbling vireo (Vireo gilvus), and Allen's hummingbird (Selasphorous sasin, CSC; ARA et al. 2002). Saltmarsh common yellowthroat occurred in riparian habitat along the former Tomasini Creek channel (ARA et al. 2002).

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California black rail

Olema Marsh was once considered "one of the most diverse habitats for breeding, wintering, and migrating birds in the Point Reyes area" (Evens 2008). Between 1991 and 1994, total number of species ranged from 77 to 81 during the winter and from 44 to 49 species during the spring (Evens and Stallcup 1991, 1992, 1993, 1994). In 2004, this species richness trend reversed, with the number of species totaling 74 in spring and 65 in winter (Stallcup and Kelly 2004). Red-winged blackbird (Agelaius phoeniceus), Marsh wren, and Song sparrow represented the most abundant species in autumn, winter, and spring, along with Saltmarsh common yellowthroat, which had at least 12 nesting territories during spring 2004 (Stallcup and Kelly 2004, 2005). California black rails (Laterallus jamaicensis coturniculus, ST) occasionally occurred in Olema Marsh, but Virginia rails were more common, along with Sora (Porzana carolina) sometimes in fall (Stallcup and Kelly 2004, 2005).

It is no coincidence that the areas showing the highest breeding bird activity prior to restoration occurred on the perimeter of the Giacomini Ranch, where the juxtaposition between managed pasture and groundwater inflow from the Inverness Ridge and Point Reyes Mesa created a diverse mosaic of habitats. In contrast, the large expanse of monotypic habitats represented by 550 acres of managed pastures were "relatively depauperate in terms of supporting breeding birds in general and special status species in particular" (ARA et al. 2002). Savannah sparrows (Passerculus sandwichensis) were observed attempting to nest in some of the managed pastures, however, as had occurred for decades, many fields were mowed during the height of nesting, thus excluding perhaps a third of their population (ARA et al. 2002). During baseline surveys, the only avian species using managed pastures as its primary habitat was Grasshopper sparrow (Ammodramus savannarum; former FSC, S2), but it arrived late and did not breed (ARA et al. 2002). Large flocks of migratory swallows sometimes foraged low over pastures and marshes, especially early and late in the day (ARA et al. 2002).

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Juvenile Northern harrier

Last year, then, breeding in the then dormant pastures reached a new zenith with discontinuation of agricultural management. (Mowing for construction purposes was only conducted after breeding had stopped, and chicks had fledged). Red-winged blackbirds, Song sparrows, and Savannah sparrows took advantage of the lush green fields, redoubling their nesting efforts and producing two broods in a single season, Evens noted. A pair of Northern harriers or Marsh hawks (Circus cyaneus) also nested in some of the fallow fields. White-tailed kites hunted the pastures by day, while Barn owls (Tyto alba) hunted them by night, feasting on the booming vole population, which also increased in response to the decrease in mowing and an increase in seed production by grasses. With the decrease in disturbance that had been caused by mowing and cattle, numbers of Wilson’s snipe (Gallinago delicata) were found foraging and roosting in the moist pasture in fall, winter and spring. (Snipe do not nest locally.)

This year, breeding activity increased yet again. Salt marsh common yellowthroat took advantage of the newly establishing riparian thickets that had been suppressed in years past by grazing. Species that had nested only along the edges of the wetland expanded their territories into the lowlands. With this increase in available habitat, larger numbers of songbirds nested and had improved reproductive success. The vegetation along lower Fish Hatchery Creek developed into a lush fresh to brackish transitional wetland lined with marsh monkey flower, watercress, reeds and rushes growing waist high. Marsh wrens, song sparrows, and Virginia rails were particularly abundant here, and a rare California black rail was calling on territory here in late April.

Waterfowl—Mallards (Anas platyrhynchos) and Gadwalls (Anas strepera)—nested amidst the moist grasslands and a pair of Cinnamon teal (Anas cyanoptera) apparently nested in the Tomasini Triangle pond. Green heron (Butorides virescens) frequented the main course of Lagunitas Creek this spring and can be expected to occur more frequently in the future as the overhanging willows expand downstream and along the creek bank. This increased riparian habitat complexity may also attract Wood ducks (Aix sponsa) and Red-shouldered hawks (Buteo lineatus)—both already seen frequently on the creek—and provide more roosting opportunities for Black-crowned night heron (Nycticorax nycticorax).

In addition to those species frequently observed or those here for breeding purposes, there were also visits from new or very rare species this spring. Flocks of White-faced ibis (Plegadis chihi)—a rare one-time visitor prior to restoration—stopped over again in Tomasini Triangle Marsh, a newly created freshwater marsh constructed two years ago. A single Black-necked stilt (Himantopus mexicanus), a very rare species here on the outer coast, foraged with other shorebirds on the flooded marshplain. Common mergansers (Mergus merganser) have been frequenting the principal tributary, Lagunitas Creek, while an adult Ferruginous hawk (Buteo regalis), another rare species, was observed flying along the sloped edges of the old ranch.

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Bald eagle

Perhaps, some of the most compelling visitors to the newly restored coastal wetland this spring have been the Bald eagle (Haliaeetus leucocephalus), which foraged over the site for a week or so in May, and the California black rails. Three California Black Rails were heard calling from the newly created marsh in April and May. This state-threatened species has all but disappeared from many of its historic habitats and has been barely clinging on to its formerly extensive habitats in Tomales Bay.

River otters

Birds were not the only common visitors to the Giacomini Wetlands this spring. River otters (Lutra canadensis sonora) also expanded their range, swimming up both the newly restored Tomasini Creek (which now winds through the East Pasture to Tomales Bay) and Fish Hatchery all the way up to Sir Francis Drake Boulevard, according to some local residents. Coyotes (Canis latrans) have become a common visitor over the last few years. Their presence will tend to exclude the non-native red foxes (Vulpes vulpes) that depredate ground-nesting birds. As the creekbank vegetation increases, it has the effect of increasing the habitat complexity underwater as well (e.g., tangled roots) and providing shade (temperature refuge) thereby increasing the diversity of aquatic invertebrates and fishes. In June, tidewater goby (Eucyclogobious newberryi, a federally endangered brackish water resident fish species, was observed in Lagunitas Creek. It had been found in Tomasini Creek during baseline surveys and later in the East and West Pastures, but had not been documented in Lagunitas Creek, one of its historic habitats, since 1953.

"Although we knew that the restoration would benefit the wetland community, no one anticipated how quickly these creatures would find their new habitat or how quickly they would exploit the diversity of new habitats created," noted Evens.

-- Content for this page was composed by Lorraine Parsons, Project Manager, Giacomini Wetland Restoration Project, Point Reyes National Seashore

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