Extinctions of Birds of the Eastern US –
160 nested, 4 have gone extinct (or is it 3?) since European settlement:
1) Carolina Parakeet
a) Once numerous throughout forests, serious agricultural pest.
b) Shot by farmers, gregarious nature made it extremely vulnerable
c) 1831 Audubon commented on declining numbers
d) Frank Chapman recorded the last wild flock in Lake Okachobee FL in 1904
e) Captive flock survived until 1918
2) Passenger pigeon
a) Once the most abundant bird on earth, with flocks that darkened the midday sky…
b) Gone by the turn of the 20th cent.
c) Why?
i) Hunting and deforestation – curiously, it was really the railroad and telegraph that drove the final nails in the coffin
ii) Key is understanding the ecology
(1) Mast fruiting of oak, beech, hickory forests to swamp predators
(2) Passenger pigeons responded by becoming nomads
(3) Formed huge nesting colonies in the spring where there was an abundance of fruit from previous year
(4) Effectively used same strategy as trees—overwhelm nest predators--One colony in Wisconsin 136,000,000 birds over 750 square miles
(a) This was good protection against hawks, foxes, coons, but not against humans
(b) From one colony in MI 100,000 lbs of pigeon meat shipped to market
iii) By late 1600s people noted declines
(1) Last major nesting in New England was in MA in 1851
(2) By 1860s big flocks gone from NY and PA
(3) Fecundity low (1/pair/yr) and most nested in a few colonies.
(4) By late 1800s last strongholds were the great lakes region.
(5) By 1878 estimates of 50,000,000
(6) By 1890 only scattered individuals could be found
iv) Railroad permitted market hunters access to even most distant colonies and ship meat back to markets and telegraph spread the word when a new colony established itself.
v) Last wild pigeon killed in Pike Co., Ohio in 1900. Martha, the last individual of the species died in the Cincinnati Zoo in 1914
vi) How did they go so fast?
(1) Hunters disturbed every breeding colony for several pigeon generations so entire cohorts died off without replacing themselves.
(2) Few stragglers nesting in small groups didn’t have the benefit of large numbers and fell prey to natural predators.
3) Ivory-billed woodpecker
a) Specialist on beetle grubs excavated from recently deceased trees in old-growth bottomland forests of the southeast.
b) Densities low—1 pr/6.25 miles
c) Disappeared below radar screens in US in last 40 yrs, but credible sighting this year (2000)?
d) Still persisting in Cuba, perhaps, but critically threatened there as well.
e) Clearly a case of low-density habitat specialist succumbing to habitat loss
4) Bachman’s Warbler
a) A curious extinction
i) Another bottomland specialist of the SE
ii) Wintered exclusively in Cuba
iii) Described by Audubon in 1833, not seen again for 50 yrs (except a sighting in Cuba). Then a flurry of sightings, but by the 30s it was already declining.
iv) Last sightings in 60s –
b) Terborgh thinks it had a very sparse population, limited by wintering grounds (Cuba) which spread out over a vast area. Population size got so low that birds couldn’t find mates.
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