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Tag Archives: adaptations

Bald Eagles, Menopause, and Ova

April 19, 2024 RaptorResource

Do bald eagles go through menopause? Probably not, since we’ve documented menopause or prolonged post-reproductive lifespans in just four species.

Oh poop shoot! What is bird poop and how do birds poop?

April 17, 2024 RaptorResource

Oh poop shoot! After a long, wet morning snuggled under Mombrella and Poptent, DN17 and DN18 needed to let it fly! Wonderful moments like this inevitably lead to questions and comments like “What is bird poop?” and “Does bird poop stink?” and ‘Ewwww…where did I put those wet wipes?‘ So what is bird poop and how do birds poop? Defecation and Excretion If someone tells us their dog pooped, defecated, or excreted, we know that the dog dropped a solid.

Canada Geese: Precocial versus Altricial

April 14, 2024 RaptorResource

As watchers know, Canada geese are nesting in two abandoned bald eagle nests in Decorah, Iowa. N2B – currently a goose nest – is located about 700 feet east of N1, where geese started hatching yesterday. This blog discusses some of the differences between altricial eagles and precocial geese! 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

What’s Up With the Geese? Canada Geese, Reproduction, and Conspecific Brood Parasitism

April 5, 2024 RaptorResource

On Saturday April 1, goose watchers at N2B saw a female goose fly into the nest. After a lot of biting, pushing, and tussling, she laid an egg despite MG and PG’s best attempts to repel her. One of the local eggs dropped out of the nest, although MG and PG ended up incorporating the intruder’s egg into their own clutch. At one point, it was thought that Canada geese were strictly monogamous. Close observation has yielded a more nuanced

Bald eagle tongues and beaks!

March 25, 2024 RaptorResource

We know that bird beaks are specialized for feeding and daily tasks. Birds of prey have strong, curved beaks with sharp edges to help them tear meat. Falcons specialize even further, adding a tomial tooth to help them kill prey. Dabbling ducks have tiny, comb-like structures on their beaks to strain small animals, insects, and plants from water and mud, while piscivorous ducks have saw-like structures to help them hold on to struggling fish. But what about bird tongues or,

How do eagles stay warm in cold weather?

January 20, 2024 RaptorResource

Each species experiences the world differently and eagles have capacities that are far different from ours. How do Bald Eagles survive an Iowa winter without adaptive clothing and central heat? A cold January morning coated our eagles in frost and left watchers wondering how Bald Eagles survive an Iowa winter. In general, wintering animals – including humans – need to retain body heat, stay dry, and take in enough calories to support winter’s increased energy demands. We humans put on

Birds and Daylight Length

December 23, 2023 RaptorResource

Many temperate and arctic animals and birds react to daylight length. Photoperiodism entrains their physiology and behavior, which helps them respond to adapt to seasonal changes in the environment. Although bird species vary in their responses, daylight length drives the annual cycle of temperate and arctic birds overall. How do birds detect changes in day length? Like many other creatures, they use photoreceptors – specialized cells that detect light and initiate a physical response. The photoreceptors in birds are not

Did You See? Bald Eagles Talon Locked on the Flyway

November 7, 2023 RaptorResource

We saw two eagles talon-locked in the water for over an hour on Sunday, November 5. Maybe locking and whirling, food theft, or an argument over who got what perching spot ended up with the two of them stuck together, unable or unwilling to release. Why didn’t they separate sooner and how strong is a bald eagle’s grip?

Bald eagle tongues and beaks!

April 11, 2023 RaptorResource

Egg Colors and Shapes

March 20, 2023 RaptorResource

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? Egg Colors Where do egg colors come from? Once a bird’s egg enters its shell gland or uterus, it is