1. Mating systems II
Blue-naped Mousebird Coliiformes

2. 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

4. Feed on fruit, buds and flowers.

5. 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.

6. 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

7. 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!

8. 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

9. 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

10. 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