A female Northern Parula bounces between branches searching for food.
The leaves in southern Arizona are just emerging, but the aphids have already discovered them.
It takes a lot of aphids to satisfy a warbler's appetite. (notice the aphid in bill) The energy expended gathering a full meal of aphids must be enormous. Parulas flit constantly.
Could aphids be that caloric?
(Click any picture to enlarge.)
It also takes dexterity and determination to find this teensy-weensy prey.
Aphids live in inaccessible places.
It's likely this Northern Parula is migrating through. Her stop here in the Sweetwater Wetlands of Tucson will be brief.
Sightings of Northern Parulas are considered rare for Arizona.
She'll probably build her nest far away... alone... in a suspended clump of moss-like vegetation. The entire eastern half of the United States and southeastern Canada is a good bet for her seasonal brood.
Oddly though, a few states will lose out. Northern Parulas typically avoid Wisconsin, Michigan and Iowa.
Clearcutting and the draining of bogs may be the reason for the Northern Parulas' decline in these States.*
They are migrating north now. Expect them soon in your state, especially if you live east of the Mississippi River.
*Credits: Cornell Lab of Ornithology, All About Birds
Sibley's Guide to Birds