Introduction

Smith’s Longspurs have one of the most unusual breeding systems known among songbirds. Restricted in the breeding season to subarctic tundra bordering the northern edge of the tree-line, this bird’s remarkable breeding behavior has been discovered only recently.

Unlike the majority of birds that breed monogamously, Smith’s Longspurs are polygynandrous—each female pairs and copulates with two or three males for a single clutch of eggs, at the same time that each male pairs and copulates with two or more females. Males are not territorial, but instead compete for fertilizations by copulating frequently in order to dilute or displace sperm from other males. Over a period of one week in June, a female longspur will copulate over 350 times on average; this is one of the highest copulation rates of any bird. Males appear well-equipped to deliver such large numbers of ejaculates—their testes are about double the mass of those of the monogamous and congeneric Lapland Longspur (C. lapponicus). As expected from their mating behavior, most Smith’s Longspur broods contain chicks of mixed paternity. At such nests, two or more males may assist females in feeding nestlings. The advantages of extra male help in raising offspring may partly explain why Smith’s Longspur females mate with more than one male.

Originally described by Swainson as the “Painted Buntling,” Audubon later redescribed and renamed this species in honor of his friend Gideon B. Smith of Baltimore.