(note, this is a back-dated post, since I wrote it a couple of weeks after the actual class…)
Another interesting class tonight, chock-full of information – read on for my notes
Range maps:
- Beware! They often gloss over migration routes, and it’s easy to misread them as indicating that a species does not exist in a region, when it does, in fact, migrate through it. If a species winters in Mexico, for example, and summers in Alaska, you can be pretty certain that it migrates across the western United States, even if that fact isn’t mentioned on the range map.
Factoid #1:: An aegrette is the name for the breeding plumes of Egrets and Herons.
Bird colors
- Nearly all blue & green colors in birds are structural colors, rather than pigment – they have their apparent color due to “tricks” of the light. Very few birds have feathers pigmented blue or green.
Carrying capactity of the environment
- The limit on the number of a species a region can support
- If the carrying capacity is exceeded, predation, starvation, and disease (and hunters, in some cases) will bring the population back down
Hummingbirds:
- Allen’s Hummingbirds are in Northern California from the last week of January through August, and can now be seen in the west end of Golden Gate Park
- Immature & female Allen’s and Rufous Hummingbirds are inseparable in the field – just call them Selasphorus sp.
- Allen’s Hummingbird migrates mostly along the California coast, while Rufous migrates mostly in the Sierra foothills.
Factoid #2: most birds have 10 primary feathers, some more, some less
Ducks, Geese & Swans
- Large-bodied, sturdy, web-footed aquatic birds
- Geese are more terrestrial than Ducks or Swans
- Male & female Geese are sexually monomorphic (they look the same)
- Ducks are either divers or dabblers.
- Dabblers have their feet forward on their bodies, divers have them toward the rear
- This is why diving ducks need a running start on the water to achieve lift-off
- Young are precocial (born relatively developed, not blind and bald)
- Mallards have 8-10 hatching chicks, but many die off early
- Female Mallards can be identified by the blotchy darkness on their otherwise orange bills
- Ducks often have 2 molts, and are flightless during the summer, since they mold their flight feathers all at once
- Male ducks in the summer often look female-like, and are flightless. This is often called “Eclipse” plumage, although it’s not a plumage at all.
- This is because ducks acquire their breeding plumage in the winter when pair selection happens, then they fly together to the breeding grounds and molt
- Most domestic escapee ducks are descendants of the Mallard
Game birds
- Don’t migrate, as a rule
- Chachalaca exist in the US only in extreme Southern Texas – it’s the only Guan that exists in North America
- Grouse have feathered legs and toes
- Lekking:
- The breeding strategy of Grouse (and some other birds, including certain hummingbirds, birds-of-paradise, cotingas, and cock-of-the-rock) is called “lekking”
- Males meet in groups and strut their stuff, puffing their neck sacs and “booming.” This is gathering is called a “lek”
- Each year, males return to the same lek
- The dominant males do most of the breeding
- Each male has it’s own little square where it struts and puffs – newcomers make their own squares at the edge of the lek, so it follows that the males in the center of the lek are the dominant ones who have been there the longest
- Females choose their mates based on who is in/near the middle of the lek
- One consequence of this is that there is a lot of incest (offspring will mate with their father if he’s still in the middle of the lek).
- Lekking happens at the crack of dawn, mostly
- Crawley Lake in N. California has a well-known Sage-grouse lek.
- A disadvantage of a lekking breeding strategy is that there is no pair-bonding, and no male parental investment
- The species formerly known as the Blue Grouse has recently been split into the Sooty & Dusky Grouse
- New World Quail:
- have a well-developed syrinx (vocal apparatus)
- The characteristic plume of a male quail consists of 8 feathers, 4 on each side
- California Quail are now rare in San Francisco due to a large intentional introduction of feral cats about 15 years ago 😦
- Only a remnant population remains in the Strybring Arboretum and the Presidio
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