29 October 2024
Final spring in the course of the nesting season I used to be so distracted by peregrines that I uncared for to test on a merlins’ nest reported in Highland Park. By the point I bought over there the younger had fledged, the merlins had been gone, and a small group of American crows had been inspecting the world and commenting on what they discovered.
Crows are intensely fascinated about merlin nests as a result of these nests could have been stolen from crows.
Merlins (Falco columbarius) by no means construct a nest. As a substitute they seek for crow or hawk nests, ideally in conifers, and take them over. If the goal nest is unoccupied no drawback however merlins are feisty and can strive for an energetic crows’ nest by driving off the incubating feminine crow. If harassing her doesn’t work, they shout at her all day till one other predator exhibits up and forces her to go away.
This usually works as a result of merlins are loud and fearless. They’ll drive away something that irritates them together with this raven (a merlin predator not a competitor).
Nonetheless, in southwestern Pennsylvania there are actually two species of crows — American crows (Corvus brachyrhynchos) and fish crows (Corvus ossifragus) — and it makes a distinction to the merlins’ success.
A 2019 research offered on the Wilson Ornithological Society confirmed that if the merlin nest was profitable, chances are high the nest had been owned by American crows.
Behavioral interactions between nest-parasitic Merlins (Falco columbarius) and nest-building Fish Crows (Corvus ossifragus) in a brand new zone of overlap explains that American crows and merlins have coexisted for millennia in order that they have cast a working relationship and attain detente early on. One or the opposite cuts their losses and nests elsewhere.
Not so with fish crows. Merlins and fish crows are new to one another in order that they haven’t labored out their variations and proceed harassing for a for much longer interval. Few or none on both aspect have a profitable nest. Within the research of 25 fish crow nests in upstate New York, 40% failed as a result of merlin interference. The research tracked 31 merlin nests and located 66% of these made in fish crow nests didn’t fledge younger.
Autumn and winter are good instances for seeing merlins and fish crows in Pittsburgh. It will be fascinating to search out them interacting in spring and watch what occurs.
p.s. Thanks to Don Nixon of PA Merlins for alerting me to this fascinating subject. The paper(*) is by Connor O’H. Loomis and Anne B. Clark (Binghamton College), John Confer (Ithaca School), Kevin J. McGowan (Cornell Lab of Ornithology) however it’s behind a pay wall. The fish crow and merlin nesting research proceed past 2019 in Ithaca, NY at Cornell Lab of Ornithology.
