Tonight was the 4th class in the second 7-class series of Introductory Field Ornithology I’ve been taking this year from CCSF. Before class I swung by Sutro Baths to see what was a-wing.As I scoped from the terrace of the baths’ ruins, two women climbed over a barrier, intended to prevent access to the less stable parts of the ruins, descended some stairs to the shore, and one of them proceeded to disrobe while the other took photographs! Birds of a different color, eh? 🙂
Avian-wise there wasn’t a whole lot afoot, although I quite enjoyed using my new Pentax XW14 eyepiece – it has an incredibly wide angle of view, and superb optics, despite the buffeting wind and spraying waves. Still new to my scope, I was amazed at how many Clark’s & Western Grebes were in the choppy waters by the Golden Gate – there were at least a couple of hundred!
In the 40 minutes I was there, I saw:
– American Coot
– Anna’s Hummingbird
– Barn Swallow
– Black Oystercatcher
– Black Phoebe
– Brandt’s Cormorant
– Brown Pelican
– Clark’s Grebe
– Cliff Swallow
– Common Raven
– Double-crested Cormorant
– Red-tailed Hawk
– Song Sparrow
– Violet-green Swallow
– Western Grebe
– Western Gull
My notes from class follow:
- Used to be 2 separate species, the Myrtle Warbler & the Audubon Warbler. A researcher discovered a zone of hybridization in Alberta, however, and they were then lumped into the Yellow-rumped Warbler, with two subspecies.
- Myrtle race YR Warblers prefer wetlands, while Audubon prefer mature forests, in the greater SF area
- The YR Warbler is the most adaptable and thus the most common warbler in the US
- The 2 subspecies have slightly different “chip” notes
- Few hybrids are seen because the zone of contact between the nesting regions of the two subspecies is very small
- If in fact they are subspecies, however, why isn’t the zone of hybridization expanding?
- Since it’s not expanding, a likely cause is that the hybrids are not selectively neutral or are at a selective disadvantage – this would point to them being separate species
- Consensus is that there is no consensus – it’s about 50/50 if they’re subspecies or full species in their own right
- YR Warbler are very variable, by season, by individual, by sex, by race, and by age.
Pigeons & Doves (Columbiaformes):
- a world-wide diverse order
- pigeons usually refer to larger, round-tails species, while doves tend to be smaller and square-tailed, but what’s in a name?
- their bills have a cover of soft tissue over the nostrils
- are all “dove-headed” – round, small heads with large eyes
- have areas of irridescence
- M & F are usually similar
- have a large crop attached to their gullet
- this produces a milky fluid called “pigeon milk” that is combined with regurgitated matter to feed the young – no other birds have this
- Band-tailed Pigeon:
- is the largest North-american pigeon, although there are Australian pigeons that are twice the size
- have a white collar
- are found along the Sierra Nevada mountains in California, south through Mexico in the Sierra Madre, and continue all the way through South America along the Andes
- The South American Band-tailed Pigeons have an all-yellow bill, while ours have a black tip
- are fond of madrone & toyon berries, as well as fruits and acorns
- breed in mature forests
- their nests are flimsy and poorly constructed, like most pigeons and doves – odd, since its generally a very successful group!
- nests are constructed by the pair – the male brings twigs, passing them to the female over her shoulder, and she then places them in the nest
- are locally common in the Bay Area, and breed on Tank Hill in SF
- are semi-migratory – they move in groups in response to food abundance/shortage
- in flight, distinguish Band-tailed Pigeons from Rock Pigeons by their uniformity (Rock Pigeons being highly variable), and their dark underwings.
- BT Pigeon was uncommon a half-century ago, with none seen on the Oakland Xmas Bird Count in the 1950s.
- They’re social birds and will flock to feeders, decimating them in no time, then waiting on a nearby wire for them to be refilled so they can do it again
- Juvenile BT Pigeon doesn’t have the white collar of the adults, and like most pigeons/doves, has a somewhat “scaly” appearance.
- More Mourning Doves are hunted annually than any other bird(!!). Most areas have a season on them, and bag limits are high.
Lories, Parakeets, Macaws, and Parrots:
- all seen in the US are escaped cage birds, although some establish semi-viable populations
- Nearly none are accepted birds for the California Checklist, although the ABA is more lenient. To get on the California list, a bid must:
- have been documented to successfully breed for 15 consecutive years
- population must be “large” and occupy most/all of the suitable habitat for it
- the only Parrot on the California list is the Red-crowned Parrot
- RC Parrot is widespread in Southern California, especially Temple City (where the heck is that?)
- there are est. ~5000 “wild” RC Parrots in S. CA, compared to only ~15,000 in the wild in their native Tamaulpais, Mexico (much of this is due to poaching in Mexico)
- The Red-masked Parakeet is the famed “Wild Parrot of Telegraph Hill.”
- White-winged and Yellow-chevroned Parakeet populations also exist at Dolores Park in SF
- Parakeets are smaller, w/pointed tails, while parrots are larger and short-tailed.
- Thick-billed Parrot:
- breeds in the Sierra Madre in Mexico
- bill is hooked to open pine cones
- they migrate according to cone availability
- travel in large flocks
- or used to, until they became endangered due to clear-cutting of the Sierra Madre’s forests
- confiscated TB Parrots were, for a time, sent to US Fish & Game in the Northeastern US, where they tried to establish a captive population.
- subsequent release of this population, unfortunately, wound up being more of a Northern Goshawk feeding program than anything else, and the release flocks all died
- Monk Parakeet:
- introduced and doing pretty well in FL, TX, and the NE
- they’re an agricultural pest in their native Argentina, as well as parts of the US, and many have been hunted
- there’s a thriving colony at Hyde Park in Chicago
Cuckoos, Roadrunners, and Anis:
- have zygodactyl(?sp) toes – two forward, two backward
- most Old World (ie Europe) Cuckoos are brood parasites
- Cuckold, n: a man who raises a child he believes to be his own, but is not. Word derived from the cuckoo’s nesting practices!
- Common Cuckoo lays eggs that look like the eggs of the species that raised it, and it seeks out that species when looking for host nests.
- desert species that eats mostly snakes, lizards, and such
- are terrestrial and sometimes climb trees, but don’t fly
- long tail is probably a rudder to assist with hunting agile lizards
- are 100% carnivorous
- used to occur with some frequency in the SF Bay Area, now occasionally seen in the Livermore hills and Santa Clara County
Factoid: Birds can’t sweat
- 2 families: Barn Owls & Typical Owls
- Are birds of prey, nocturnal, and feed on mammals
- have strong claws and bills, usually eating rodents whole
- Barn Owls are, unsurprisingly, named for where they nest
- All owls have a facial disk
- this is thought to focus sound into their large ears
- Owls have large ears which are often asymmetric, though to assist with spatial location of prey
- eyes are cylindrical and cannot turn in their sockets, hence owls having very turnable heads
- owls have 16 cervical vertebrae compared to humans’ 7.
- swans have 26, giraffes have 7 (all mammals have 7)
- Barn Owls are fairly scarce in the Bay Area unless there is a rodent outbreak
- Barn Owls have a dark and light morph, the dark being more common in the West
- Typical Owls
- Great Horned Owl is the most common owl in the Bay Area
- are fairly common locally
- exhibit reverse sexual dimorphism (females are larger than males)
- ear tufts aren’t part of the ear at all, and their function is unknown
- Great Horned Owl is the most common owl in the Bay Area