BirdNote; Mating Strategy of the Saltmarsh Sparrow

BirdNote®

Mating Strategy of the Saltmarsh Sparrow

Written by Rick Wright

This is BirdNote.

[Saltmarsh Sparrow, ML 163475]

Saltmarsh Sparrow: the name tells us everything we need to know about this bird’s habitat. But it discreetly leaves unmentioned this species’ biggest secret: its free-love mating behavior in the tidal marshes of the East Coast.

[Saltmarsh Sparrow, ML 163475]

New techniques for analyzing the parentage of chicks have shown that “extra-pair copulations”, or non-monogamous relationships in birds, are not as rare as once believed. But the Saltmarsh Sparrow takes it to an extreme, with a breeding strategy described by scientists as featuring “a... bond-free relationship between males and females.”

[Saltmarsh Sparrow, ML 163475]

Meaning that males and females copulate with multiple individuals of the opposite sex, and then they go their merry way.

[Saltmarsh Sparrow, ML 163475]

The female builds her nest alone, where she incubates the eggs and feeds the hatchlings. If a male approaches while she’s busy, she drives him away -— and he doesn’t come back.

[Saltmarsh Sparrow, ML 163475]

Due to historic habitat loss and rising sea levels, Saltmarsh Sparrows are at serious risk of extinction—but it’s not for lack of trying on her part.

For BirdNote, I’m Michael Stein.

Today’s show brought to you by the Bobolink Foundation.

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Producer: John Kessler

Production Manager: Allison Wilson

Editor: Ashley Ahearn

Producer: Mark Bramhill

Associate Producer: Ellen Blackstone

Saltmarsh Sparrow, ML 163475, provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York, and recorded by Gregory Budney.

BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.

© 2020 BirdNote November Narrator: Michael Stein

ID# SALS-02-2020-11-05 SALS-02

References:

© Birds of the World, Cornell Lab: The mating system practiced by this species is very unusual among birds and features an obligate, promiscuous, bond-free relationship between males and females (10, 167, 150, 114, 104, 121). Hill et al. (167) provided genetic evidence that confirmed observational evidence of promiscuity in species (see below), and discovered one of the highest levels of non-bond-related mating reported in any bird. See Multiple Paternity in Broods, below.

And: Males that accidentally discover a nest during construction (or later in the nest cycle) are driven off by the female and evidently seldom return (JSG, unpublished data).