Shawn Billerman is a graduate student at the University of Wyoming studying birds, though his degree will likely use fancier words than that. He is a New Yorker, a great birder, and a nice guy. You may remember him spotting a shrike in Brooklyn from the passenger seat of Corey’s car back in December. Though some aspects of Shawn’s post have been touched upon in Felonious Jive’s, this post is well worth the read. Enjoy!

The world of birds is full of odd and interesting behaviors.  Many of the most peculiar aspects of birds are involved with mating, whether it’s for attracting mates, defending nests against predators, or raising chicks.  One of the more interesting aspects (in my opinion) of breeding in birds is their mating strategy.  There are four main mating strategies in birds: 1) monogamy, 2) polygyny, 3) polyandry, and 4) polygynandry.

The most common mating strategy in birds is social monogamy, found in roughly 92% of birds species in the world (Jenni 1974, Owens 2002).  Social monogamy is where one male and one female pair and share the responsibilities of nest building, incubation, and chick feeding (Jenni 1974, Owens 2002).  The second most common breeding strategy, found in about 8% of bird species in the world, is promiscuity and polygyny, where a male will mate with multiple females and form no pair bond, and usually provide no help to the female in any aspect of nesting.  In polygyny, females will often nest on territories held by a male, with multiple females nesting on a single male’s territory, as in Red-winged Blackbirds (Yasukawa and Searcy 1995).  Promiscuity, where females get no care or resources from males, include lek breeding birds, and has led to some of the most spectacular male displays and plumages through female sexual selection; one needs only look at the stunning birds-of-paradise (Paradiseidae) of New Guinea and Australia, or, closer to home (for us in North America), the lekking displays of Greater Sage Grouse (Centrocercus urophasianus) or any of the prairie-chickens (Tympanuchus) (Jenni 1974, Schroeder et al. 1999).

The third type of mating system, where the traditional sex-roles are reversed, found in roughly 0.4% of all bird species, is polyandry.  In this system, females mate and lay eggs with multiple males over the course of a breeding season, leaving males to incubate the eggs and raise the chicks.  Polyandry is found mostly in shorebirds (e.g. phalaropes, jacanas, etc) (Jenni 1974, Owens 2002).  The final, rarest mating strategy, found in less than 0.1% of all bird species, is polygynandry, where both males and females mate with multiple individuals.  In polygynandrous systems, broods may be raised by groups of males (either with or without the help of females) (Briskie 1992, 2009, Nakamura 1998).  While polygynandry is extremely rare, it is found in a wide variety of birds, ranging from the Hihi (Notiomystis cincta), a New Zealand endemic, to tinamous (Tinamidae) (Hanford and Mares 1985, Castro et al. 1996, Nakamura 1998).

the polygynandrous Smith’s Longspur by Shawn Billerman

Birders in North America are lucky enough to encounter some amazing birds with some amazing breeding biology.  During the summers of 2009 and 2010, I was lucky enough to work in Churchill, Manitoba, studying Hudsonian Godwits (Limosa haemastica) (see here for a post about the godwits of Churchill).  Churchill is an amazing place, especially for someone who loves shorebirds.  Churchill is also cool because it hosts species that have some of the rarest mating strategies among birds in the world, including polyandrous and polygynandrous species.  While there aren’t tinamous roaming the sub-arctic tundra shores of Hudson Bay, there are Smith’s Longspurs (Calcarius pictus).  The mating system of Smith’s Longspurs has been described as “female-defence polygynandry.”  In this system, females mate with 2-3 males, and males usually mate with 2-3 females (Briskie 1992, 2009, Briskie et al. 1998).  A single female often lays a clutch of eggs sired by multiple males, and multiple males will in turn help care for the chicks once they hatch (Briskie 1992, 2009, Briskie et al. 1998).  Additionally, female Smith’s Longspurs have one of the highest rates of copulation of any bird, mating an average of 365 times over the course of a week while eggs are being laid (Briskie 1992, 2009, Briskie et al. 1998).  While working in Churchill, we had the opportunity to observe many Smith’s Longspurs as we searched for godwit nests.

the polyandrous Red-necked Phalarope by Shawn Billerman

In addition to the polygynandrous Smith’s Longspur, Churchill is also home to some other great birds, including the Red-necked Phalarope (Phalaropus lobatus), a polyandrous breeding species (Reynolds 1987, Rubega et al. 2000).  As mentioned above, in a typical polyandrous mating system, females will compete for males, and will pair only to lay a clutch of eggs, before leaving the male to lay another clutch of eggs with a new male (Reynolds 1987, Rubega et al. 2000).  It has been suggested that polyandry evolves in birds when per-clutch fecundity is low or fixed (Jenni 1974), or when there is a female-biased opportunities for remating, such that birds with polyandry nest at very low densities (Owens 2002).  By laying multiple clutches with different males, a female is able to increase her reproductive fitness (Jenni 1974).  In Red-necked Phalaropes, not all females are polyandrous, and most are monogamous.  In a study of phalaropes near Churchill, only 8% of females were polyandrous (Reynolds 1987).  For individuals that were polyandrous, a pair bond with a male only lasted 11 days, and ended when the final egg of a clutch was laid.  A female would then pair with a new male 7 days later and lay a new clutch of eggs (Reynolds 1987, Rubega et al. 2000).  While Red-necked Phalaropes are the only polyandrous species in Churchill, the other two phalarope species are also polyandrous, with Red Phalarope (Phalaropus fulicarius) passing through Churchill during spring migration (Shamel and Tracy 1977).

 the polyandrous Red Phalarope by Shawn Billerman



Briskie, JV (1992) Copulation patterns and sperm competition in the polygynandrous Smith’s Longspur. The Auk, 109(3) 563-575

Briskie, JV, R Montgomerie, T Poldmaa, and PT Boag (1998) Paternity and paternal care in the polygynandrous Smith’s Longspur. Behavioral Ecology and Sociobiology, 43(3) 181-190

Briskie, JV (2009) Smith’s Longspur (Calcarius pictus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of Nroth America Online

Hanford, P and MA Mares (1985) The mating systems of ratites and tinamous: an evolutionary perspective. Biological Journal of the Linnean Society, 25 77-104

Jenni, DA (1974) Evolution of polyandry in birds. American Zoologist, 14(1) 129-144

Nakamura, M (1998) Multiple mating and cooperative breeding in polygynandrous alpine accentors. I. Competition among females. Animal Behavior, 55 259-275

Owens, IPF (2002) Male-only care and classical polyandry in birds: phylogeny, ecology and sex differences in remating opportunities. Philosophical Transactions of the Royal Society London B, 357 283-293

Reynolds, JD (1987) Mating system and nesting biology of the Red-necked Phalarope: what constrains polyandry. Ibis, 129 225-242

Rubega, MA, D Schamel, and DM Tracy (2000) Red-necked Phalarope (Phalaropus lobatus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of Nroth America Online

Schroeder, MA, JR Young, CE Braun (1999) Greater Sage-Grouse (Centrocercus urophasianus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of Nroth America Online

Shamel, D and D Tracy (1977) Polyandry, replacement clutches, and site tenacity in the Red Phalarope (Phalaropus fulicarius) at Barrow, Alaska. Bird-Banding, 48(4) 314-324

Yasukawa, K and WA Searcy (1995) Red-winged Blackbird (Agelaius phoeniceus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of Nroth America Online

A fish may love a bird, but where would they live?

-Drew Barrymore

Bird Love Week is seven days of exploration of avian amore here on 10,000 Birds from April 22-28. We love birds, and the topic of birds loving other birds and in the process making more birds is a fascinating one we know you will enjoy. Mike, Corey, and a bevy of Beat Writers have been working on this one for awhile as the perfect expression of our love of all things avian. To see all of our Bird Love Week posts, just click here. But be warned – Bird Love Week is neither for the faint of heart nor for the permanently prudish – you may end up with images that you never imagined seared onto your brain.


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