Friday, April 23, 2010

Spotted Sandpiper

Most of my female friends rolled their eyes when I told them about bright male White-throated Sparrows' propensity for promiscuity and about male bluebirds taking on extra mates.  In case you were beginning to think that males are only good for collecting multiple mates,  consider the Spotted Sandpiper.

Pairs of Solitary Sandpipers court, and males will chase after females.  Females also fight over males.  Females often begin building nests, although often the males finish the job. After the females lay their eggs, males suffer a ten-fold decrease in testosterone levels, and have high levels of proclatin.  These hormones leave the males in a domestic mood, and they brood the eggs until the young hatch and are on their own. (Females will occasionally lay their eggs in other Spotted Sandpiper's nests, the young of these nests being raised by unrelated males.)

Upon laying their eggs, the females usually mate with a second male, and abandon their first mates.  If the females help with incubating, brooding, or nest guarding at all, it is with her second mate.  Occasionally females take on a third mate, abandoning the second.  One result of all these multiple matings is that, unlike in more traditional birds, few males lack a brood.  Furthermore, the sex ratio often gets skewed so that many populations of Spotted Sandpipers have more males than females.

I am not sure what is up with the Spotted Sandpiper "yawn" in the photo above.  Perhaps more likely it is regurgitating arthropod exoskeletons from its gullet.  Females, however, do perform a choking display when courting males. (I did not, however, see any other nearby Spotted Sandpipers when I took this photo at Sand Lake National Wildlife Refuge in South Dakota.)

My source for this blog entry is: Oring, Lewis W., Elizabeth M. Gray and J. Michael Reed. 1997. Spotted Sandpiper (Actitis macularius), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu.bnaproxy.birds.cornell.edu/bna/species/289

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