Friday, October 22, 2010

Sparrow season.

Immature White-crowned Sparrow, Zonotrichia leucophrys

Hmm, Sparrow Season, that sounds a bit too much like duck season or deer season. Most of the neotropical migrants have already passed through on their way back to the tropics, and now is the time when we notice sparrows. They're seed-eaters, and we typically find them scratching under shrubs, skulking in dense tangles and searching the edges of gardens.

The sparrows we've seen at West Campus this week are typical for this time of year. Our year-round Song Sparrows, our winter White-throated Sparrows and Dark-eyed Juncos and our migratory Savannah and White-crowned Sparrows all made the checklist this week.

Many of our migrating birds head to warmer climes because their food supply (insects) is gone. But many of our familiar summer birds instead switch from a diet of invertebrates to a fruit-based diet. This conversion has been widely studied - with respect to nutrition, digestion, pre-migration fattening and food source availability.

The classic example from West Campus would be the American Robin - worms and insects in summer, berries and crab apples in winter. I've added a few reference articles at the end of this post.

Science in our back yard...

How about the week's bird list?
Wild Turkey
Canada Goose
Herring Gull
Ring-billed Gull
Turkey Vulture
Red-tailed Hawk
Sharp-shinned Hawk
American Kestrel
Rock Pigeon
Mourning Dove

Monk Parakeet
Downy Woodpecker
Northern Flicker
-- no Phoebes!! --
American Crow
American Robin
European Starling
Northern Mockingbird
Gray Catbird
Black-capped Chickadee

White-breasted Nuthatch
Brown Creeper
Golden-crowned Kinglet
Yellow-rumped Warbler
Northern Cardinal
Song Sparrow
White-throated Sparrow
White-crowned Sparrow - immature
Savannah Sparrow
Dark-eyed Junco

American Goldfinch
House Finch
House Sparrow

Thirty-three species for the week. Not bad, still holding on to our decent numbers, but the days of a high count of twelve species for the week are ahead of us... o frabjous day! callooh! callay!
ciao, have a great weekend!

There are so many articles on the subject of diet in birds, I chose one which was relevant to dietary shifts and pre-migratory fattening.
okay, and another one about sugar-rich vs lipid-rich fruit choice in the American Robin
there's so much more - I didn't even scratch the surface!

No comments:

Post a Comment