Swamp Sparrow Nest Departure Call
Imagine you are a female coastal plain swamp sparrow sitting on eggs. You get hungry and decide to go forage. You slip off the nest, fly low to the ground, and then utter a loud series of call notes. What? Why advertise your presence? Isn't that a dead giveaway to predators as to where your nest is?
Not only female coastal plain swamp sparrows but 16 other species in North America and Europe exhibit the same behavior. Several reasons have been proposed for this odd behavior:
- Prevention of harassment by males
- Advertisement to males of receptivity
- Warning to other females
- Encourage to males to look out for predators
- Distracting predators away from nest
All the birds that call when leaving the nest are birds that live in grasslands, marshes, or other open habitats. Typically, the birds live in small territories packed close together. The most likely reason appears to be that the females are trying to avoid harassment by males that are very aggressive in protecting their territories.
This article summarizes the information in this scientific paper:
McDonald, M. V. and Greenberg, Russell S. 1991. Nest departure calls in female songbirds. The Condor, 93: 365-373.
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