A Lot of Noise About Hummers
Contributed by Cabrillo National Monument Volunteer Claude Edwards
Lately, there has been a lot of excitement about the presence of hummingbirds that have been observed visiting CabrilloNational Monument and other portions of Point Loma on their northbound migration. This is an annual occurrence that draws much interest within the overall spring migration period, which also brings numerous other species of birds en route to their breeding grounds.
There are several species of hummers that can be found during this period as they zip past craning heads and late-pointing fingers of those who would attempt to distinguish them “on the fly.” Only when they pause for a few fleeting seconds, or even perch for a minute or two, can sharp-eyed hummer-hunters put a name to particular individuals, given proper line of sight and lighting.
The familiar Anna’s hummingbirds (Calypte anna) are year-round residents that nest and raise their young in our vicinity. Their numbers are apparently bolstered in late winter and early spring as males set up breeding territories and announce their presence with scratchy songs and dive-bombing aerial displays. Prior to the colorful arrays of flowers that typically signify the arrival of spring, they seem to survive on the barest of native and planted nectar sources that they can find on slopes and along walkways around the park during and following the winter rains.
Anna’s hummingbirds remain the most numerous species throughout the migration period, aggressively defending favorite blooming trees, shrubs, and wildflowers from the speeding passersby, and perhaps even comprising a part of their numbers, as indistinguishable migratory birds interact with resident territorial ones.
The dominant truly migratory hummingbirds that are found and reported at this time of year are the Allen’s (Selasphorus sasin) and rufous Hummingbirds (Selasphorus rufus). These are “sibling species” - that is, they are closely related species in the same genus. They both spend the winter in Mexico and conspicuously travel north along the coast, as early as February and extending to late April. Only the males can be safely identified, and even then, some cannot be determined without appropriate lighting or the presence of varying amounts of green feathers on their upperparts.
The males in this group can be located by their metallic wing-buzzing as they fly past or change positions while visiting flowering plants. Another feature they have in common is their flaming orange-red gorget, or feathers on their throat, that are best seen in good light. Females of the two species share orange-to-peach coloration on their sides and lower back, but are usually left unidentified.
In April, the species that really gets bird-watchers into a tizzy are the diminutive dynamos of American birds, the calliope hummingbird (Stellula calliope). The males are unique, having red-and-white striped gorgets rather than uniformly colored throats featured by the adult males of other species. They are the smallest bird in the country and in our region, barely more than three inches in length. Since they are observed while on migration, individuals that are reported are rarely seen by those that attempt to relocate them later. Female calliopes resemble pint-sized female Selasphoru‘, with orange-tinted sides, along with proportionately shorter bills and tails, but this is subtle.
Individuals and small groups of binocular-clasping observers move between and gather expectantly around blooming bottlebrush trees (Callistemon citrinus) and New Zealand Christmas trees (Metrosideros excelsus), as well as native sages (Salvia apiana and Salvia mellifera), monkeyflowers (Mimulus aurantiacus), and other blooming plants. It is almost as if they themselves are part of the spring bird migration, and along with the other species they find and report, are in fact part of that annual phenomenon.
Two other hummingbird species that can be found visiting Cabrillo Monument and other parts of Point Loma are clack-chinned hummingbird (Archilochus alexendri) and Costa’s hummingbird (Calypte costae), occurring in smaller numbers than those described above.
Thus, there is good reason for such small and relatively unobtrusive birds to create such clamor and activity in our midst.
Did You Know?
Did you know that a fossilized fern was found at the tidepools of Cabrillo National Monument? It is now housed at the San Diego Natural History Museum.