Tuesday, May 6, 2014

Angry Rose-breasted Grosbeak

This is one angry bird. I forgot what pain a Rose-breasted Grosbeak can inflict upon a bander. Grosbeaks returned to Northfield on 4 May, and I banded this one on the fifth.

You might think that a species with such an out-sized bill might specialize on a particular, larger food item. In fact, Rose-breasted Grosbeaks are generalists when it comes to food. Wyatt and Francis (2002) cite an extensive study that found that invertebrates (beetles, bees, ants, bugs, and caterpillars) comprised 52% of their diet. Wild fruit comes in next at 19.3%, followed by weed seeds (15.7%), and cultivated crops and fruit (6.5%). Finally, some 6.5% of the diet included other vegetable matter, like tree flowers and buds and galls.

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