Species at Risk
Along the Nectar Trail
by Bob Benson, Bat Conservation International
It was early June in the Sonoran Desert of southern Arizona as I watched
several lesser long-nosed bats (Leptonycteris curasoae) enjoy a meal of
nectar at a flowering agave. With the aid of a night-vision scope, I witnessed
these nectar-feeders under the cover of darkness as they acrobatically
danced from bloom to bloom, affecting cross-pollination.
These bats live in caves and abandoned mines of North America's southwestern
deserts. They form nursery colonies of thousands of mothers and young
in northern Mexico and the extreme southwestern United States. Bachelor
colonies are separate and smaller. The arrival of these highly nomadic
bats in the Sonoran Desert coincides with agave and cacti blooming cycles,
mostly in June and July, when young bats are born and reared.
Long-nosed bats travel in groups and fly up to 30 miles to reach food,
with the largest colonies covering as much as 19,000 square miles a night.
Groups tend to feed for about 20 minutes, then pause briefly to digest
their food before continuing. Amazingly, the bats spend less than one
second feeding within the flowering blooms, yet they may come back to
a single flower more than 150 times a night.
These bats migrate in the spring and fall between southern Mexico and
the United States, relying on the sequential flowering of more than 60
species of agaves and cacti as they travel. Long-nosed bats pollinate
both agaves and cacti and are equally important as seed-dispersers for
giant cacti, such as organ pipe, saguaro, and cardon.
The bats and their food plants have become so highly interdependent that
loss of long-nosed bats could threaten the health of entire desert ecosystems.
In fact, one study documented that the seed production of certain agaves
drops to 1/3000 of normal without bat pollinators. This is of concern
to the tequila industry, because although most agave used in the production
of tequila is a managed crop, wild populations of agave provide the genetic
material for new varieties.
Long-nosed bats are listed as endangered by the Mexican and U.S. governments.
Loss of feeding habitat and roosting caves are the primary threats to
their survival. Thousands of bats at a time are killed when their caves
are burned by people who mistakenly believe them to be vampire bats.
Through the Partnership for Conservation of Migratory Bats (co-founded
by Bat Conservation International, a nonprofit organization dedicated
to conservation of bat species worldwide, and the Institute of Ecology
at Mexico's National University) people on both sides of the border are
beginning to learn to value and protect these bats, and growing numbers
of key roosting caves are now being restored and protected. The Partnership
is now a model for other Latin American countries and many are following
its lead, implementing strategic bat conservation and management plans.
For more information, contact Bob Benson, Bat Conservation International,
PO Box 162603 Austin, Texas 78716-2603, (512) 327-9721, firstname.lastname@example.org,
Growing Up in a Tidal Marsh
by Bruce Taylor, Oregon Wetlands Joint Venture
Fish researchers on Oregon's south coast are coming up with dramatic
new findings about the importance of tidal marsh habitats for juvenile
On-going studies at South Slough National Estuarine Research Reserve
on Coos Bay have documented extensive use of tidal marshes and off-channel
rearing ponds by young coho salmon. Fish biologists have traditionally
discounted the importance of estuarine habitats for coho, which are listed
as threatened under the United States' Endangered Species Act. That view
was based on the assumption that young coho salmon paused only briefly
in these habitats as they migrated from their natal streams to the ocean.
However, trapping of juvenile coho coming out of South Slough's Winchester
Creek in southwest Oregon revealed a more complex life history pattern
than previously thought.
A portion of the coho fishery moved down into tidal areas almost immediately
after hatching, while some spent up to a year in the upper estuarine habitats.
Other juveniles remained in the upper watershed for 8 to 12 months before
beginning their downstream migration. Those fish lingered in the upper
estuary for periods ranging from a week to as much as 6 months.
Juvenile fish that moved into tidal areas early in their life grew almost
twice as fast as those reared in the upper watershed. These findings could
provide one of the keys to improving salmon productivity, since direct
links have already been established between the size of out-migrating
juvenile fish and their early ocean-survival rates. Simply put, the bigger
the fish as it enters the ocean the better its chance for survival and
return to the spawning grounds at the end of its life cycle.
Crucial, then, to increasing survival rates is habitat availability,
but after more than a century of diking, filling, and developing tidal
wetlands, the amount of habitat available has been greatly reduced. In
effect, juvenile salmon have been cut off from much of what would historically
have provided some of their most productive habitat.
Partners of the North American Waterfowl Management Plan's Pacific Coast
Joint Venture recently restored diked pastures along South Slough to their
former function, creating about 50 acres of tidal marshes—a rich source
of food for young salmon. "The juveniles we trap in the marshes, their
stomachs are just completely full," says Bruce Miller of the Oregon Department
of Fish and Wildlife. "They weigh substantially more than those of the
same population that we trap in tidal channels. It is directly attributable
to their foraging in the marshes. Ten years ago these areas weren't open
to fish. Now, they're providing great habitat."
The recovery of endangered fisheries requires the recovery of the habitats
they need. In restoring these habitats, all creatures in the food chain
will benefit, from insects to birds to humans.
For more information, contact Steve Sadro, Oregon Institute of Marine
Biology, Box 5417, Charleston, Oregon 97420, (541) 888-2581, extension
305, email@example.com, or Bruce Miller, Oregon Department of Fish
and Wildlife, Box 5430, Charleston, Oregon 97420, (541) 888-5515, firstname.lastname@example.org.
Running Out of Reptiles
by Rosemary Forrest, Savannah River Ecology Laboratory
National attention has been riveted on the issue of amphibian declines
for years and has intensified with each new report of vanishing populations
or deformities. However, according to an article in the August 11, 2000,
issue of the journal BioScience, reptiles are in even greater distress
worldwide than their better known cousins.
These two vertebrate classes are collectively referred to as herpetofauna,
but the focus of general concern has been almost exclusively on amphibians.
Now, however, scientists are hoping that the general public will recognize
what they have long known: reptiles across the globe are affected by many
of the same forces as amphibians but with even greater impact. \
The article's lead author, Dr. Whit Gibbons, a herpetologist and professor
of ecology at the University of Georgia, said, "Although the amphibian
decline problem is a serious threat, reptiles appear to be in even greater
danger of extinction worldwide." He said that while studies on both amphibians
and reptiles have not been as rigorous as scientists would like, the existing
documentation points to a coming crisis situation.
The problem is multifaceted, but habitat loss and degradation may be
the largest single factor in reptile loss. For even when part of a habitat
is protected, such as a wetland, the surrounding terrestrial habitat needed
by semiaquatic reptiles often is not. Conservation biologists hold as
a basic tenet of ecology that intact habitat is necessary for species
persistence and well-being, but habitat destruction is just the beginning
of the problem. Invasive species introduced to new areas can spell real
danger for reptiles. Other problems include environmental pollution, disease,
and even the simple presence of humans among a fragile population. Cars
kill reptiles; cats and dogs hunt reptilian prey; and people take interesting
reptiles from their environment or handle them incorrectly.
The commercial use of reptiles is also cited as a cause for declines.
The harvesting of reptiles for pets, food, and for use in folk medicines
can result in overcollection. This kind of use affects reptiles more than
amphibians. Human use is not universally bad, according to Gibbons, but
such use should be "sustainable," that is, the population from which individuals
are harvested should be able to rebound to at least the same population
Global climate changes may also present problems for reptiles, according
to the BioScience article, and some population declines have been
noted for which a cause cannot be discerned.
Many populations thought to be in decline simply have not been monitored
over long periods of time, making evaluation of the problem difficult.
Additionally, the clandestine nature of many reptiles and their large
home ranges may allow a population to decline without notice.
"The disappearance of reptiles from the natural world is genuine and
should be a matter of concern," according to Gibbons. "Current evidence
suggests that these declines constitute a worldwide crisis."
For more information, contact Rosemary Forrest, University of Georgia,
Savannah River Ecology Laboratory, P.O. Drawer E, Aiken, South Carolina
29802, (803) 725-2473, email@example.com.