Julie Craves describes why orioles eat peanuts and why murre eggs don’t roll off ledges

8/28/2014 | 0

Baltimore Oriole by Janet Crouch

Baltimore Oriole by Janet Crouch

In the column “Since You Asked” in every issue of BirdWatching, Contributing Editor Julie Craves answers readers’ questions about birds and bird behavior. Here are two questions from our October 2014 issue:

Last spring I watched orioles eating peanuts from my feeders. Is this unusual? — Lynn Carson, Rockford, Illinois

This happened at my home, too. Occasionally, an oriole would grab a peanut or a shelled sunflower chip. I had never seen orioles do this. The birds typically eat small insects, which feed on the new growth of plants, or the nectar of early-flowering trees such as crabapples, serviceberries, and plums. After the long, cold winter of 2013-14, many trees were late in leafing out and flowering. My guess is that the orioles were looking for added protein or fat to supplement the oranges and jelly available at feeding stations.

A Common Murre incubates an egg. In Europe, the species is known as Common Guillemot. Photo by Steve Garvie (Creative Commons)

A Common Murre incubates an egg. In Europe, the species is known as Common Guillemot. Photo by Steve Garvie (Creative Commons)

I saw a television program that showed Common Murres nesting on tiny ledges on cliffs. Why don’t the eggs roll off the ledges? — Paul O’Donnell, Buffalo, New York

Common Murres don’t build a nest but instead lay one egg directly on a rocky ledge. The eggs of murres, as well as those of many other cliff-­dwelling species, are not oval like a chicken egg but are pyriform, or pear-shaped. That is, they have one narrow, pointed end. When eggs on a ledge are pushed or shoved, they roll in a circle, not straight, so they are not likely to roll over the side.

Many shorebirds, which typically nest on the ground, also lay eggs that are more pointed at one end. While they are not in danger of rolling off a ledge, the shape allows the eggs to fit closely together, facilitating heat transfer from the incubating parent.

About Julie Craves

Julie-Craves-120Julie is supervisor of avian research at the Rouge River Bird Observatory at the University of Michigan Dearborn and a research associate at the university’s Environmental Interpretive Center. She writes about her research on the blog Net Results, and she maintains the website Coffee & Conservation, a thorough resource on where coffee comes from and its impact on wild birds.

Read other questions that Julie has answered in “Since You Asked.”

If you have a question about birds for Julie, send it to ask@birdwatchingdaily.com or visit our Contact pageA version of this article was published in the October 2014 issue of BirdWatching. Subscribe.