Vireos are, for the most part, among the more challenging birds to
identify. Consummate "dickey birds", vireos are small and often fleeting,
twittering around the tops of trees and hiding out in particularly
difficult to find locations. The warbling Vireo is no exception. Its back
is drab olive green. The breast is mostly white with some pale yellow
along the sides. A gray eyebrow is the only real feature distinguishing it
from other local vireos. Vireos are slightly larger than warblers with a
thicker bill.
Habitat
Don t worry too much about having to identify a drab Warbling Vireo.
Like a lot of songbirds, you hear them more often than you ll see it. They
inhabit dense shrubby cover and young deciduous re-growth. Often these
woods are along stream sides, although they are found higher up into the
mountains where shrubby avalanche paths are a popular location.
All vireos are part of the larger group of birds known as "neotropical
migrants." These birds nest in North America and migrate south to winter
in Central and South America, often in tropical rainforest habitats. The
Warbling Vireo winters from NW Mexico south to El Salvador.
Behaviour
What vireos lack in dazzling colour, most make up in song. Warbling
Vireos earned their name from their vocal virtuosity. Long warbling
phrases ending on a high note indicated this little songster is nearby.
An interesting behavioural trait is that the male does the majority of
egg incubation, a rare example of Mr. Mom among songbirds. Even more
strange is that he often sings while sitting on the nest. This is odd
because such song could well attract nest predators. Perhaps this is why
Warbling Vireos are particularly at risk to brown-headed cowbird nest
parasitism. Cowbirds lay their eggs in other birds nest and leave the host
parents to raise the cowbird young, often at the expense of their own.
However, the males are quite bold around the nest, as is shown in this
picture, taken locally near the forks of the White River.
Field Notes
Warbling Vireos begin to arrive in the Columbia Valley in early May,
just in time for Wings Over the Rockies Bird Festival! Shrubby stream-side
bushes are good places to look for this bird. There are many excursions
planned for this years Festival to get you out and about and looking with
eyes and ears for the Warbling Vireo
