lecture 20 Flashcards
Facultative brood parasites
lay eggs in own nest and nests of conspecifics (same species); common trait, particularly in colonial and cavity-nesting species
Obligate parasites
lay eggs only in the nests of other species- can’t lay eggs in own species because their own species doesn’t even build nests; 1% of all bird species
Intraspecific brood parasitism- experiment bar headed goose
within-species brood parasitism; looked at percent survival of host and donor offspring before and after a parasitic act; survival of recipient offspring decreased after parasitic act and survival of donor offspring increased
Jawfish
example of interspecific brood parasitism; when danger, suck young into its mouth
Brown headed cowbird
ultimate host generalist brood parasite; lays eggs in over 200 different species’ nests, most (90%) successfully raise the cowbird offspring; continue to grow more generalist over time- able to parasitize more species
Cowbird study: effect of cowbird offspring size relative to host nestlings and probability that cowbird will get fed
when cowbird is a greater height than host nestlings, has a much greater chance of getting fed than when a lower height than the host nestlings
why tolerate parasite’s eggs?
Rejection has costs- some birds do not recognize parasitic eggs and even if the host does recognize it, still a chance of rejecting one of its own eggs in error
Cowbird study- fitness costs to host for rejecting eggs
when cowbird eggs were rejected by host, cowbirds showed high predation- used mafia strategy and destroyed host nest as revenge; cowbirds also used farming strategy where they destroyed the host nest if the host eggs were too developed for the cowbird egg to blend in
Adoption: Goldeneye duck example
in ducks, little to no cost of adoption because chicks forage for themselves; they also benefit from increased number of offspring due to the dilution effect
Costs of group living
competition for mates, nest sites and food; increased visibility for both predators and prey; spread of disease and parasites
Swallow bug study of nest infection
as number of nests (group size) increased, percent of nests infected with swallow bugs increased; supports the increase in parasite transmission due to group living
Study of group size effect on male relatedness to offspring
as increase group size (nest density), percentage of offspring related to male decreases; increases probability that you will help raise offspring that are not your own
Reproductive interference
includes egg-dumping (wood ducks) and egg-tossing (acorn woodpeckers); decreases reproductive fitness
Costs of being subordinate- cichlid fish
spend mass majority of time doing behaviors unrelated to reproduction
Energetic cost of behavior study-paper wasps
the more aggressive the behavior, the lower median energy expended per act
Long-tailed manakins- Cooperative courtship
pair of males performs a routine to impress the female; there is a younger male apprentice and an older male teacher who gets to mate; over time, younger male will take on an apprentice of his own and he will get to mate
Benefits of group living
increased ability to locate mates; increased ability to detect predators; benefits of group defense (dilution effect, selfish herd, etc), increased hunting efficiency; improved foraging
African wild dogs study- increased hunting efficiency
as the pack size increases, the net energy consumption per dog increases
Ravens- Yelling recruitment signals
when ravens come across dead animals, let out a recruitment calls; only non-territorial ravens let out these calls in order to bring in other non-territorial ravens (the territory owners don’t)
Survivorship insurance in paper wasps
when colonies were set up by single foundresses, there was already a decrease in colonies because some foundresses were killed off by predators in the process; when nests were founded by multiple foundresses, there was not a decrease in colonies that survived because if one founder died, there would be another that could take over
Social vaccination in termites
when a heat-sensitive infective spore which can destroy larvae was experimentally introduced into the hive, temperature skyrocketed in the brood comb in order to kill off infective spore
Heat shielding in honey bees
maintain heat inside hive by contracting flight muscles; use heat in response to pathogens; requires a group to carry out heat shielding
