Mating systems II Blue-naped Mousebird Coliiformes

Several females may lay in a single nest Coliiformes 6 species, all African Lack feather tracts Travel in flocks Several females may lay in a single nest White-backed Mousebird

Feed on fruit, buds and flowers.

The topic of mating systems, covered in two lectures, is presented in the previous ppt. This lecture continued mating systems and presented the order of the day. A few slides deleted to save time are given next.

Resource Defense Polygyny Imagine a female arriving in an area, seeking a mate. What should she do? Mate with already-mated male who has a very high quality territory (Less help from male) Mate with “single” male, who has an average or poor quality territory (More help from male) Male Female = high quality territory = low quality territory Polygyny Threshold Hypothesis: A female will pick an already-mated male when she can raise more young than with a single male

Testing the Polygyny Threshold Hypothesis Prediction: A male’s territory quality will be correlated with his mating success. Experiment: Lark Buntings (Wanda Pleszczynska) They feed off their territories (food on territory not important) Nest in open fields (hot); most nest mortality due to heat exposure; shady nest sites (bushes) are important. Males with more bushes have two females When bushes are added to territories, males get more mates!

Polyandry [Gr. andr, man] 1 female, 2 or more males Rare, <1% of birds Many polyandrous species are sandpipers Females defend territories & compete for males Females are larger and more colorful

Spotted Sandpipers An example of sequential polyandry Breed in the arctic (lots of insects) Very large eggs and precocial young Female can produce 5 clutches in 40 days (20 eggs; 4 times her body weight!) Females compete for males Most females produce far fewer than 40 eggs

Simultaneous Polyandry Very rare Female holds a large territory, with several males in it. Female lays eggs into nests of all “her” males. Genetic relationships not well worked out Jacana Tinamou