L4 Why is "adaptive radiation a major theme in the biodiversity of birds?
Adaptive radiation = rapid speciation. Birds began speciated 65 million years ago, and now are 10,000 sp. (greatest of terrestrial vertebrates). The observed biodiversity of birds is due to adaptive radiation.
L4 How are "biodiversity hotspots" defined and which definition(s) can best conserve birds?
Avian biodiversity studies:
Diversity in life history
Diversity over time: adaptive radiation
Diversity over space: hotspots
How many sp. of birds i comparison to mammal and reptiles?
10,000 sp. birds
5,700 sp. mammals
8,200 sp. reptiles
What measures of birds do we measure life history diversity?
Body size and flight (e.g. Hummingbird, peregrine falcon, penguin, and ostrich)
Diversity in diet and beak shape
Diversity in reproductive rate and lifespan (e.g. albatross, ducks, and songbirds)
Biodiversity and evolutionary history
Species are organized into taxonomic groups based on their evolutionary history
The phylogeny shows which birds are descended from a recent common ancestor
Diversity over time: Evolutionary history overall
Most extant Orders of birds evolved in the past 65 million years, after the extinction of the dinosaurs
The oldest extant orders of birds include the Pheasants/grouse, ducks/geese, and Ostriches and rheas
Diversity over time: evolutionary history Passeriforms
evolved relatively recently. Most closely related to parrots than to woodpeckers or owls
Diversity over time: evolutionary history
Hummingbirds and swifts are closely related (tiny feet, narrow wings, very flexible shoulder joint)
450 sp. (2nd most diverse order)
We don't know the closest relatives of hoatzins or flamingos
Specialized and unique taxa
Only 1 sp. of Hoatzin; SA birds that eats leaves and ferments them for digestion
Nestlings have claws on writst for tree climbing
In its own order (evolutionary history still debated)
Specialized and unique taxa
6 sp. of flamingo in world
Unique beak for filter feeding upside-down to eat tiny brine shrimp
Some DNA evidence suggests herons are closest relatives
But recent genetic study found thatgrebes were more closely related
Diversity & Adaptive Radiation
Passeriformes = ~ 5,000sp
Adaptive radiation = rapid high rate of speciation
Hummingbirds/swifts = ~450 sp.
Adaptive radiation: passerines (perching birds)
Order Passeriformes contains half of the world's birds = 5,000 sp.
Includes flycatchers, crows, vireos, thrushes, tanagers, warblers, sparrows, blackbirds, etc.
Order evolved most recently and underwent a MASSIVE adaptive radiation (rapid and high rate of speciation)
Adaaptive radiation on Islands
Diet and hawaiian Honeycreepers: Nectar, fruit, seed, insect, generalists
Diet and Darwin's Finches: insects, seeds, cactus flowers
Adaptive radiation on continents:
Habitat and Parulidae (New World Warbler)
In N. Missouri, cowbird parasitism rate (% nests with cowbird eggs) decreased by 50%
Number of cowbird eggs per nest (intensity) also decreased sharply over time
Heavily forested S. Missouri: No significant increase in productivity over time (note these populations have double the productivity compared with N. missouri)
In N. Missouri where forest cover is low (23% cover) and cowbirds have decreased, the # fledglings per nest increased by 30%
Cowbird removal experiment
Griffith and Griffith 2000
% vireo nests parasitized decreased with increased female cowbirds killed per year
Least Bell's vireo population increased with removal of cowbirds
(vireo from west coast in california and mexico)
Fragmentation and nest predator
Nest predator are also more abundant in fragmented landscapes
Agricultural matrix provides artificical source of food, and increases population sizes of mice, chipmunks, raccoons, skunks, crows, blue jays, etc.
In small forest fragments it is common for over 60% of nests to be eaten by predators
Edge effect and nest predation
Cox et al. 2012
Edge nests have about 60% nest predation while "only" 40% of forest interior nests are eaten by predators
Small fragments have a higher proportion of edge habitat than large fragments
Overall predation rate decreases strongly as distance of the nest to the edge of the forest increases
Edge nests had more predation by snake and raptors
Source and sink
Source: average female produces more young than necessary to replace herself when she dies
Sink: average female produces fewer young than necessary to replace herself when she dies
Are small forest fragments sinks?
Because expect more parasitism and nest predation
Measured productivity and fledgling survival
Found dozens of nests, monitor each nest every 3-4 days to determine how many are preyed upon, parasitized, then radio-track the fledglings to see how may survive the 3-weeks after fledgling
Number of eggs laid per female -> number of young fledged per female -> number of fledgling per female surviving the next 3 weeks -> Number of juveniles surviving migration to breed the next year (estimated survival to next year based on other studies)
Hooded warbler: 0.31< 0.50 (female morality)
Rose breasted Grosbeak: 0.24 < 0.50
Cat predation and adult bird mortality
Domestic cats are non-native predator on birds and other small animals
U.S. ~84 million pet cats; 30-80 feral cats
Monitored impact by using kitty cam, and reported prey captures by owners
Kill rate was 12 birds/hunting cat/year
50-80% of pet cats hunt wild animals (according to owners)
feral cats 80-100% hunt wild animals
Kill rate of birds varies greatly mong studies due to different prey base and methods
1-34 birds killed/pet cat/year
24-51 birds killed/un-owned cat/year
Ran the model thousands of times by randomly selecting different values for all the variables,within the obsered range
Most models predict 2-3 billion birds killed by cats each year in US!
Cat kill far more birds than ANY other human caused bird mortality
Cats: 200-300 million birds/year
Window Collisions: 25 million birds/year
Wind turbines: 24,000 birds/year
Forest fragmentation does what?
What does Cat kills amount to?
Decrease nesting productivity of song birds due to higher number of cowbirds and nest predators
Forest fragments are usually population sinks, where breeding productivity is too low to replace adult mortality. Leads to population declines.
Cats kills billions (2-3) of birds in NA each year, and are 10x more lethal than even window collisions.
What is the evidence that cowbirds are an important cause of population declines of songbirds?
Population level correlation (Missouri) and experimental (removal)
How did researchers estimate the number of adult birds killed by cats?