Blog #376 Building a Nest with Just Your Feet


How do big birds like Ospreys and eagles get materials for their large stick nests? It takes an average Osprey pair 2–3 weeks to build a new nest containing hundreds of sticks and branches 1–5 feet long and lined with a softer cup made of bark, sod, grasses, moss, twigs, vines, cornstalks, algae, or human-derived debris scavenged from the ground. The male fetches most of the woody nesting material—breaking dead limbs off nearby trees as he flies past or picking them off the ground—and the female positions it, although some studies report the female collecting nearly half of the sticks. Not all these sticks are accepted; some are dropped off the edge into a pile collecting around the nest pole base. Why she accepts or rejects a stick is only known to her. And sometimes a stick prized one week will be discarded the next.


Nests built on artificial platforms, especially in a pair’s first season, are relatively small—less than 2.5 feet in diameter and 3–6 inches deep, but after years of adding to the nest, they can become 10–13 feet tall, 3–6 feet in diameter, and weigh half a ton. Take the time to watch this time-lapse sequence of Ospreys building their nest from scratch: https://www.youtube.com/watch?v=TY75wSMp2p8.


Seeing the males break branches from trees is fascinating. He flies through the trees at quite a clip, searching for a dead branch. How he can tell which branches are dead when the leaves have not budded yet is another mystery. They do not appear to test sticks ahead of time to see which will break off and which will fling them backward like a slingshot. Below is a montage of Orpheus choosing and breaking off a stick to place in the nest. This stick broke off rather easily. 


Orpheus selects a stick to break, courtesy of Cindy and Karel Sedlacek.


Orpheus grabs the stick and continues to fly while holding on, courtesy of Cindy and Karel Sedlacek.



CRACK! It breaks! Orpheus flies off to the nest with his prize stick, courtesy of Cindy and Karel Sedlacek.

Orpheus collects the majority of nest material, while Ophelia screens it for quality control and arranges and rearranges it in the nest. It’s virtually impossible to tell which sticks will pass muster with a nesting female and for how long, as they each have their own sense of taste and timing. All told, the process of finding, grabbing, and vetting nest materials is quite mysterious.



Eyes to the sky!

Candace


Candace E. Cornell 

Friends of Salt Point, Lansing, NY

Cayuga Lake Osprey Network

cec222@gmail.com


Thank you to photographers Cindy and Karel Sedlacek, Ithaca’s Osprey photographers extraordinaire.


EYES TO THE SKY!


WATCH!

Salt Point Osprey Nest Cam


READ!

On Osprey Time: Ospreys of Salt Point


VISIT!

Cayuga Lake Osprey Trail



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