Birds
From ANIMAL PEOPLE, November 1993:
Cowbirds, native to the
midwest, invaded California 10 to 15
years ago and are now blamed for extir-
pating at least four threatened or endan-
gered songbirds from key parts of their
range. Female cowbirds indirectly kill
as many as 48 young songbirds apiece
per nesting season by laying their eggs
in songbirds’ nests. The songbird par-
ents then raise the fast-hatching cowbird
offspring ––who push the songbirds’
own eggs out before they hatch.
Songbird species such as the Bell’s
vireo, willow flycatcher, yellow-breast-
ed chat, and white crown sparrow are
believed capable of withstanding losses
of 10% of their eggs, but decline quick-
ly when the losses exceed 20%. Studies
of white crown sparrow nests in San
Francisco’s Golden Gate Park indicate
losses to cowbirds may exceed 50%.
Hopes for the eventual recovery of the
highly endangered Bell’s vireo were
raised this year when one or two pairs
reportedly nested along the Ventura
River, near Santa Barbara, for the first
time since 1908––but a lone Bell’s vireo
seen in Monterey County, a former
stronghold of the species, failed to find
a mate. Bell’s vireos apparently haven’t
nested successfully there since the cow-
birds arrived, circa 1983.
Longline tuna boats from
Japan, Korea, Taiwan, China, Russia,
the Ukraine, and the U.S. kill 44,000
albatrosses a year in the Southern Ocean
and south Indian Ocean, charge New
Zealand ornithologists Barry Weeber
and Sandy Bartle. The global albatross
population is estimated at only 200,000
breeding pairs, including just 10,000
pairs of the wandering albatross––half
as many as a decade ago. Mating for
life, the wandering albatross has a nor-
mal lifespan of up to 50 years, and lays
just one egg every two years. The par-
ents take turns guarding the egg in 55-
day shifts, during which they fast,
never leaving the nest. Between shifts,
they soar away on feeding flights up to
9,300 miles long over open ocean. The
albatrosses are hooked and drowned,
along with petrels, mollymawks, and
other seabirds, when they try to snatch
bait from the longliners’ 80-mile strings
of as many as 2,500 tuna hooks. One
longliner reportedly killed 500 seabirds
in three weeks recently, while another
killed 200 albatrosses on a single string.
The California Forestry
Association on October 6 asked the
U.S. Fish and Wildlife Service to
remove the California spotted owl popu-
lation from the endangered species list.
The USFWS put the total spotted owl
population at 5,000 when it was
declared endangered in 1990, but recent
studies funded by the timber industry
claim there are 8,500 spotted owls in
California alone. Although 18 species
have been removed from the endangered
species list due to extinction or recov-
ery, none have ever been removed
either at request of industry or because
of erroneous population data. The CFA
action came one day before the White
House announced it had settled lawsuits
filed by 12 environmental groups on
behalf of the spotted owl with a pact that
would allow limited old-growth logging
between now and next year, when a 10-
year forest management plan engineered
by the Clinton administration is to take
effect. Several of the groups charged
that the White House strongarmed them
into accepting the concessions by threat-
ening to exempt the 10-year plan from
existing environmental laws.
The U.S. Fish and Wildlife
Service on October 11 proposed remov-
ing the Arctic peregrine falcon from the
endangered species list. Only about
2,000 peregrines remained in the U.S. in
1970, when they first got federal pro-
tection. Absorption of DDT accumulat-
ed in the body fat of their prey caused
the falcons’ eggs to crack prematurely.
Since DDT was banned, the peregrine
population has grown to 5,000-10,000,
many of them dwelling on the sides of
tall buildings in big cities, where they
eat pigeons. The Peregrine Fund has
turned its attention to the aplomado fal-
con, jeopardized by pesticides used on
cotton crops and rarely seen in the U.S.
during the past 40 years. In 1985 the
Peregrine Fund imported several pairs
from Chihuahua state, Mexico, and
demonstrated that they could breed in
captivity, releasing 24 offspring at the
Laguna Atacosta National Wildlife
Refuge in Texas. Before going ahead
with full-scale captive breeding, the
Peregrine Fund asked the federal gov-
ernment to ban use of the suspect pesti-
cides in Cameron County, which
includes Laguna Acosta, and has an
abnormally high rate of birth defects in
humans, similarly linked to pesticide
exposure. After protracted negotiation,
local cotton growers agreed to change
their pesticide application methods
instead. Up to 50 aplomados are now to
be released in each of the next 10 years.
Areas rich in biodiversity
aren’t necessarily rich in rare species,
according to a comparative study of
2,500 grid squares of 10 kilometers each
done in Great Britain by the Center for
Population Biology at the University of
London’s Imperial College. Counting
birds, butterflies, dragonflies, aquatic
plants, and liverworts, the researchers
found little overlap in their most favored
habitats, and often found the scarcest
species in the least favorable habitat.
The findings a challenge the theory of
habitat protection advanced by U.S.
Interior Secretary Bruce Babbitt, who
hopes to shift the focus of endangered
species protection from protecting
species one by one to protecting critical
habitats for multiple species. The
British study indicates that the scarcest
species tend to be those with highly spe-
cialized adaptations to essentially unfa-
vorable habitat.
