Tag Archives: adaptations

Canada Geese: Precocial versus Altricial

Canada Geese at 24 hours old, Charlo Osprey Nest, explore.org, just prior to the Big Leap

Altricial eaglets rely on parental care until they fledge. But goslings are precocial: capable of moving around, self-feeding, and leaving the nest shortly after hatch. What does that mean? Read on to learn more! Canada Geese and Bald Eagles: Precocial versus Altricial From Stanford University: A precocial bird is “capable of moving around on its own soon after hatching.” The word comes from the same Latin root as “precocious.” Altricial means “incapable of moving around on its own soon after

Egg Colors and Shapes

The Chicago Peregrine Program inspired me to write a quick blog on the colors and shapes of eggs. Bald eagles have white eggs, peregrine falcons have eggs that range from light cream through brick red, and red-tailed hawks have pale eggs that are lightly splotched with brown. How and why do the birds we watch lay differently-colored and shaped eggs? In general, female birds inherit egg colors and patterns from their female parents. Egg-shell is made primarily of calcium carbonate,

How do eagles stay warm in cold weather?

January 14, 2021: Eagles at Lock and Dam Seven on Lake Onalaska, Mississippi River

Iowa bald eagles nest in extremely cold weather. How do they stay warm?  Bald eagles maximize energy gain by foraging in groups, gorging food, and increasing the assimilation of ingested food energy. They minimize energy loss by reducing activity, seeking protective microclimates, and lowering their nocturnal body temperature. In short, eagles keep warm by using the least amount of energy to get the most amount of food. Group Foraging and Changes in Behavior All bald eagles reduce activity and seek shelter during

Four Foraging Stories from the Flyway

October 24, 2021: Mississippi Flyway

It’s late October and the birds we watch on the Mississippi Flyway are pouring south while local plant and animal populations dwindle in response to diminishing daylight length, colder temperatures, and reduced food availability. How do migrating birds find enough to eat in the diverse, rapidly changing habitats they travel through? Read these four foraging stories to learn more about how birds cope with the challenge of finding food on migration! River Dreaming Picture a Mississippi River lake: a lake

Eagle Eyes!

Human Eye versus Eagle Eye

Has anyone ever called you eagle-eyed? Relative to humans, bald eagles have larger, sharper eyes that see further, collect more details, and produce stereoscopic vision to greatly improve depth perception. A bald eagle’s visual acuity begins with its eye size and shape. Dad’s somewhat tubular eyes occupy over 50% of the volume of his skull, as compared with less than 5% in us spherically-eyed human types.  He can voluntarily adjust the curvature of his large cornea and lens (we’re restricted