Tuesday, January 4, 2011

Red-shafted Flicker winter feeding

Red-shafted flicker, a northern flicker subspecies, Colaptes auratus (1st described by Linneaus), is a colorful and fairly large woodpecker. Name in part may have come from its call, an onomatopoeia "flicka, flicka, flicka..." Like all birds it spends much of its day searching for food. Dietary research published by Arthur Cleveland Bent (1939) revealed stomach contents that contained 40% vegetable matter and 60% animal matter. Majority of animal matter consumed was ants (75%). Most of the vegetable matter consists of fruits and berries.


Red-shafted flicker looking over the berry selection
In the winter ants are not readily available. So much of the search for food now consists of searching nooks, crannies for other arthropods (insects, centipedes, spiders, crustaceans). Arthropods overwinter in four forms, from most to least in number: egg, larvae, pupa or adult. Each form has advantages/disadvantages to surviving the winter. Moore and Lee Jr. (1991) described cold hardiness of aquatic and terrestrial insects. A fly larvae of Eurosta solidaginis withstood -55F winter temps in a goldenrod gall. Further research suggested that insects specifically choose sites for wintering on the basis of: size, shelter, position, and moisture content. Waldbauer (1998) calculated that one square mile of airspace from 20 feet above the ground to 500 feet up contained 32 million arthropods. Abundance increases closer to the ground. So, flickers and most birds, likely have a lot to food to find, albeit small.

The TwitPic photo posted shows two flickers searching my neighbor's brick chimney for wintering arthropods. Seems like a difficult way of living...geez these animals are incredible and tough. CX7K4Z9RYUGY