March 23, 2017

Stories to Tell – Nature’s Scavengers

By Eric D'Aleo, Naturalist

One thing is certain; nothing ever goes to waste in nature. This seems especially true in the winter when food is scarce. Something that was once passed over by an animal when food was abundant may now be an important source of nutrition even if it is carrion. However, some wildlife never turns away from this free meal. These animals we call scavengers. When we think of scavengers several species may come to mind -- turkey vultures, carrion beetles, and fly larvae to name a few. However, many predatory animals may scavenge for food at some time during the year, particularly in winter. Here in New Hampshire scavengers may include fox, skunk, raccoon, opossum, bobcat, coyote, and eagles. Two additional birds often seen scavenging on Science Center property in the winter are ravens and crows. Both of these opportunists feed on a variety of food during the summer including fruit, grain, small invertebrates, bird eggs, nestlings, mice, and carrion. But during winter their diet is more limited and they scavenge more often.

Both ravens and crows have been seen scavenging through the Science Center's compost pile searching for food. They seem to prefer to visit the area at different times with the ravens most often seen earlier in the morning than the crows. When looking at images from the same location of the two birds it’s easier to see the difference in their physical appearance.

The raven is clearly larger than the crow and has a thicker, sturdier bill. The crow’s bill is more slender, which makes it more challenging for it to feed on carrion since it’s harder for it to puncture the skin of a dead animal, squirrel sized or larger. The raven’s bill, being larger and heavier, is better able to handle the force needed to feed on an animal carcass.

The raven has a shaggy ruff of feathers sometimes visible around its throat and on its legs that the crow does not have. This gives ravens a rougher and stockier appearance. There is also a difference between their tail feathers. A crow’s tail feathers are all the same length so that when they are spread it appears fan-shaped. A raven’s tail feathers are longer in the center of the tail than on the edges, giving its tail a wedge shape when the feathers are spread.
Both species are social, but ravens are most often seen in pairs while crows are more likely to be seen in family groups.
Look at the two images below and see if you can identify which bird is the crow and which one is the raven. Keep an eye out for these intelligent birds during the rest of the winter to observe their scavenging strategy for survival firsthand.

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