Amphibian and reptile numbers fall by 75% in reserve meant to save them

[Pastor Dale Morgan]

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Perilous Times and Global Warming*
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Amphibian and reptile numbers fall by 75% in reserve meant to save them*

Death in the rainforest: fragile creatures give the world a new climate
warning

Ian Sample, science correspondent
Tuesday April 17, 2007
The Guardian

A protected rainforest in one of the world's richest biodiversity
hotspots has suffered an alarming collapse in amphibians and reptiles,
suggesting such havens may fail to slow the creatures' slide towards
global extinction.

Conservationists working in a lowland forest reserve at La Selva in
Costa Rica used biological records dating from 1970 to show that species
of frogs, toads, lizards, snakes and salamanders have plummeted on
average 75% in the past 35 years.

Dramatic falls in amphibian and reptile numbers elsewhere in the world
have been blamed on habitat destruction and the fungal disease
chytridiomycosis, which has inflicted a devastating toll across central
and South America. But scientists hoped many species would continue to
thrive in dedicated reserves, where building, land-clearance and
agricultural chemicals are banned.

The new findings suggest an unknown ecological effect is behind at least
some of the sudden losses and have prompted scientists to call for
urgent studies in other protected forest areas. The researchers, led by
Maureen Donelly at Florida International University, believe climate
change has brought warmer, wetter weather to the refuge, with the
knock-on effect of reducing the amount of leaf litter on the forest
floor. Nearly all of the species rely on leaf litter to some extent,
either using it for shelter, or feeding on insects that eat the leaves.

The study revealed sharp declines among two species of salamander, whose
numbers fell on average 14.52% every year between 1970 and 2005. Frog
species slumped too, with numbers of the mimicking rain frog falling
13.49%, the common tink frog 6.69%, and the strawberry poison frog 1.18%
a year. Lizards suffered similar falls, with one species, the striped
litter skink, down 10.03% each year, and orange-tailed geckos declining
by 8.05% every year.

The researchers also analysed weather records for the region, which
revealed a rise of more than 1C in temperature over the 35-year period
and a doubling of the number of wet days. The study was published in the
journal Proceedings of the National Academy of Sciences yesterday. "All
of the falls recorded elsewhere have been in high, mountainous regions
and those have mostly been driven by the spread of fungus. All of the
tests we've done for the fungus here have been negative," said Steven
Whitfield, a co-author of the study.

"Our best guess is that the declines are related to a drop in leaf
litter on the forest floor. Most of the species use leaf material as a
place to hide, but because it's moist, it's also a place to shelter when
it's dry and warm. Many of these species also feed on the insects that
eat the leaf matter, so if that disappears, so does their food and shelter."

The scientists say it is crucial to extend the study to other protected
forests, such as those in Peru, Ecuador and Colombia, to assess the
populations of amphibians and reptiles there.

"If we are to design effective conservation strategies, we need to know
what's causing these declines. If it's down to a link between climate
and leaf litter, then we need to better understand that," said Mr Whitfield.

Amphibians are considered delicate sentinels of environmental change.
Sudden population collapses were first noticed during the 1980s, during
which more than 120 species are thought to have become extinct.

In Britain, the common toad population is "seriously threatened", with
natterjack toads having declined by 75% in the past century. Numbers of
great crested newts in the country have dropped by 60% since the 1960s.

Last year, English Nature announced that the chytridiomycosis had
arrived in Britain following the escape of infected bullfrogs imported
from North America. The organisation destroyed 11,000 frogs in an
attempt to contain the spread.

The collapse of amphibian populations prompted 50 of the world's leading
conservation experts to call last year for an urgent mission to save
them from extinction. In a letter to the US journal Science, the
conservationists proposed a $400m (£217m) plan called the Amphibian
Survival Alliance, which would dispatch teams to collect endangered
amphibians for captive breeding.

John Fa, director of conservation science at the Durrell Wildlife
Conservation Trust in Jersey, said: "Something needs to be done in terms
of saving these species, and maybe that is captive breeding, but it's
difficult. You have to know that even if you're able to breed up the
numbers, will they survive in the environment when you put them back?"

Declined at least 75% in the past 35 years, even in protected areas:
Common salamander; strawberry poison frog; Bransford's litter frog;
broad-headed rain frog; Noble's rain frog; mimicking rain frog; common
tink frog; Warszewitsch's frog; orange-tailed gecko; leaf litter lizard;
striped litter skink.