Did you actually read the info on the site? And I have 90 acres of property
with a beaver pond and swamp area - I am not going to control the mosquito
larvae in those areas. I am not talking about city populations of bats dear.
I am talking about natural forested areas - or what is left of them. If a
National Park wants to increase the population of bats, martens or swallows
what is the big deal to you?
Are you an ecologist specialising in Bats? or mosquito populations? On what
basis are you refuting this? The site you posted only spoke of Mexican bats
that inhabit southern areas. Do you have other published references that
have disproven bat population density has no affect on mosquito populations?


"animaux" wrote in message
...
Bats do not eat enough mosquitoes, nor to martins, to call them helpful
in
controlling mosquito populations. Believe what you want, but the site you
gave
me tells me nothing other than showing a bat and a MOTH which it found in
flight
by echolocation.

It's a large myth that bats control mosquito populations as it is a myth
martins
make any dent. The way to control or manage them is up to the homeowners
who
leave out water in tubs, tires, plastic containers, bags, debris which can
capture water, etc. Our pond had Bt-Israelensis to control mosquito
larva.

Like I said, bats eat them, but to make them a primary management tool of
mosquitoes is silly and uninformed.


On Sun, 02 Nov 2003 17:42:42 GMT, "Tina Gibson" opined:

It is not silly - in Canada (and I am sure in the northern US) the brown
bat
is a very well known mosquito catcher. Like most mammals - each species
or
subspecies has it's own niche. Maybe the mexican free tailed bat eats
mostly moths but there are bats that eat a LOT of mosquitos - just gotta
find the right ones. Even the ones who don't if they're eating that many
insects a night its worth having a few.
BTW puple martins are excellent mosquito catchers too!! Worth putting in
a
purple martin house if you ar ein mosquito country - which I definitely
am
in.
The bat population in Northwestern ontario has been drastically reduced
in
the last 30 yrs by deforestation and there is currently a move to try and
repopulate.
Tina
Check out this link
http://www.cws-scf.ec.gc.ca/hww-fap/...cies=51&lang=e

"animaux" wrote in message
.. .
Well, this is silly. Bats like to eat beefy moths and other larger
flying
insects. They do eat mosquitoes, but not nearly the amount people'd
have
you
believe.

Taken from this website:
www.batcon.org


THE LIVES OF Mexican Free-tailed Bats
BY MERLIN D. TUTTLE

AS BATS GO, Mexican freetailed bats (Tadarida brasiliensis) may not be
much to
look at; they're drab in color, ranging from dark brown to grey, and
they
have
the characteristic wrinkled lips that others of their genus share. Some
have
described them as looking like little gnomes with an overbite. They get
their
name from their tail, which protrudes freely beyond the tail membrane.

Despite their rather plain appearance, these are some of the world's
most
intriguing bats. Speedsters of the bat world, they have been clocked
flying at
60 miles per hour using tail winds, and at altitudes over 10,000 feet,
higher
than any other bat. Free-tails can live in an atmosphere more like
another
planet than earth, one that can quickly kill most other creatures,
including
humans. And they form colonies larger than any other bat, larger, in
fact,
than
any warm-blooded animal in the world.

The largest populations of Mexican free-tailed bats live in Central
Texas
and
Mexico, but they are also common throughout much of western North
America,
southward through Central America, and into the arid and semi arid
regions
of
western and southern South America. They live in many habitats,
including
urban
areas, and range- from deserts to piñon-juniper woodlands and pine-oak
forests.
Although bachelor colonies of free-tails have been found at elevations
over
9,000 feet, large nursery colonies tend to prefer relatively dry areas
below
5,000 feet. Mexican free-tails typically live in caves, abandoned
mines,
or
tunnels, and also roost in buildings, under bridges, in rock shelters,
in
hollow
trees, and in cliff-face crevices.

Mexican free-tailed bats are also known as "guano bats" for the
prodigious
quantities of droppings that they produce. Extraction of guano for use
as
natural fertilizer was once big business, and some is still sold
commercially.
From 1903 to 1923, at least 100,000 tons were removed from Carlsbad
Caverns
alone and sold to fruit growers in California. According to Charles
Campbell,
Bracken and Frio caves in Central Texas on average each produced 75 to
80
tons
annually in the early 1900s. Officials of the Southern Pacific Railroad
estimated that, early this century, they annually transported 65
carloads
of
30,000 pounds each from Texas, making bat guano the state's largest
mineral
export before oil. Bracken Cave, now owned and protected by BCI, was
still
producing from 80 to 85 tons per year in the late 1980s.

Each free-tail cave is also a potential treasure trove for
biotechnologists.
Microbiologist Bernie Steele examined guano from Bracken Cave, finding
that a
single ounce contains billions of bacteria. He concluded that the cave
contains
thousands of species of bacteria, many of which may live nowhere else,
and
most
of which we know nothing about. Species he identified produce enzymes
useful in
detoxifying industrial wastes, producing natural insecticides,
improving
detergents, and converting waste byproducts into alcohol. A large
proportion are
also potential sources of new antibiotics. Stratified guano deposits in
free-tail bat caves have also been used to monitor environmental
pollution
and
to investigate prehistoric climatic changes.
Free-tailed bats have supported several American war efforts as well.
When
Confederacy ports were blockaded in the latter part of 1863, a gun
powder
factory was established near San Antonio. The powder's most valuable
ingredient,
saltpeter, was made from local bat guano. During World War 11, major
free-tailed
bat caves near San Antonio were carefully guarded during top-secret
research
coded "Project X-Ray."* The U.S. Air Force hoped to use bats as
carriers
of
small incendiary bombs that would be dropped on Japan. The project
began
to lose
favor when escaped bat bombardiers set fire to air base barracks and a
general's
car. After being passed on to the Navy, and finally the Marine Corps,
the
project was canceled.

WHILE MOST PEOPLE are unaware of the presence of these bats in their
area,
Mexican free-tails are very much a part of life in Central Texas, where
the
largest populations in the United States make their summer homes. These
huge
colonies, several numbering in the millions each, are where mothers
congregate
to give birth. The importance of these nursery sites is enormous; bats
born here
help replenish colonies throughout much of the Southwest and other
areas.

Bats begin arriving in Central Texas in late February, having migrated
from
overwintering sites in Mexico. Active year-round, free-tails do not
hibernate.
just before their northward migration, they mate. Although young males
apparently do not reach sexual maturity until their second year, female
s
as
young as a year old have been found pregnant.

By summer, male and female free-tails will have divided into bachelor
and
nursery colonies. Bachelor groups are relatively small, consisting of
dozens to
hundreds of individuals, but can number 100,000 or more. In contrast,
most
nursery colonies are large, numbering from the hundreds of thousands to
millions. Bracken Cave is home to some 20 million free-tailed bats, a
population
that almost doubles when the bats give birth. This is the largest known
bat
colony in the world.

Typically, each female produces just one young, and virtually all give
birth
during a brief span of time, peaking between the first and third weeks
of
June.
Birth periods may vary from year to year since weather differences can
affect
the length of gestation. Newborn young, called pups, weigh nearly a
quarter of
their mother's weight and are often more than half as long.

Mothers give birth while clinging to the roost with both thumbs and one
or
both
feet. Babies are born naked, often with their eyes open. As soon as the
baby is
born, the mother carefully cleans and nurses it. For up to an hour, the
newborn
remains attached to its mother by the umbilical cord, safeguarding
against
falls
and allowing time to learn one another's scent and voice before
becoming
separated.

Eventually, the mother pulls away to dislodge the placenta, which
remains
attached to the baby until it dries and falls off a day or two later.
Pups
have
an instinctual tenacious clinging response, using their large feet and
thumbs to
hold on to walls and their tiny incisor teeth to cling to mothers or
other
bats.
Richard Davis reported during his research that when a single baby was
removed
from a cave wall, as many as 15 could be pulled off as each clung to
the
next.

Each cave appears to have favored areas where young are deposited year
after
year. Gary McCracken and Mary Gustin, who conducted extensive research
on
the
huge nursery colonies of Central Texas, found average roosting
densities
of 400
pups per square foot and sometimes as many as 500. As the thousands of
pups
squeak, jostle, and crawl over one another, the cave walls are alive
with
constant motion and sound.

With so much confusion, it had long been believed that mothers nursed
the
first
pup they found. But McCracken postulated just the opposite. Using
sophisticated
genetic analysis of mothers with nursing young, he documented that
nursing
is
not random. He and Gustin then used specially marked mother and young
pairs,
monitoring them with nightviewing devices attached to video cameras, to
show
that each mother finds and nurses her own pup multiple times daily.

They found that mothers roost apart in adult clusters, remembering the
approximate locations of their pups. Since pups may move from a few
inches
to
over a yard between feedings, locating them among the thousands of
others
is a
remarkable feat. Mothers and pups recognize each other's unique voices
at
least
three feet away and move toward one other despite the incredible
confusion
of
calls emanating from countless thousands of other bats. Multiple
landings
are
typically required to find a pup, each bracketing its location in a
manner
suggesting that a mother is triangulating her pup's voice. Finding her
young can
take as little as 12 seconds to nearly 10 minutes. She most commonly
feeds
her
pup before she goes out to feed and again when she returns in the
morning.

Final recognition is by scent, though it remains to be discovered
whether
the
scent is placed on the pup from glands on the mother's face, or whether
each pup
has its own unique odor. A successful reunion ends with a mother
touching
the
top of her pup's head with her muzzle, apparently smelling and
exchanging
vocalizations with it. Such exchanges can last for a minute or more
before
the
mother raises her folded wing and nudges the pup toward one of her
breasts.

Over a 24-hour period, she may produce as much as a quarter of her own
body
weight in milk. Young free-tails grow rapidly, benefitting from
prodigious
quantities of this extremely rich
milk. They reach adult mass and learn to fly when four to five weeks
old
and are
weaned within approximately five to six weeks.

On its first attempt at flight, a young free-tail must avoid several
mid-air
collisions per second, relying on an as yet untested navigation system
in
a dark
cave. Although amazingly few serious collisions occur, those that do
can
break
wings or ground a bat long enough to be attacked by swarms of dermestid
beetles
and their larva that live on the floors of most free-tailed bat caves.
As
with
other bats, the heaviest mortality probably occurs in the first year,
perhaps as
much as 50 percent.

Predation at entrances to nursery caves increases dramatically as the
young bats
learn to fly. Avian predators are many, with red-tailed hawks and owls
the
most
common, catching flying bats during emergence and occasionally entering
caves to
catch those roosting near entrances. Raccoons, opossums, skunks, and
other
mammals also prey on the emerging bats, as well as several types of
large
snakes. Given the huge numbers of bats present, such predators likely
have
relatively little impact.
WITH COLONIES OF this size, cave temperatures are raised dramatically.
In
Bracken Cave, the 20 million mother bats, with a body mass roughly
equal
to 271
tons, generate an enormous amount of heat. During summer, the cave's
temperature
varies only one-sixth as much as the outside; without its bats, Bracken
Cave's
walls likely would be less than 68 F. Shared body heat raises average
wall
temperatures to 88 F, enabling the bats to maintain cluster
temperatures
of
100-105 with greatly reduced energy expenditure. As the summer
progresses,
however, bats may overheat the cave, forcing large numbers of roosting
individuals to extend and
flap their wings or even take flight to cool down.

With fresh droppings and occasional dead bats falling to the floor in
Bracken,
dermestid beetles begin to multiply. By mid-summer, their numbers can
be
truly
astronomical, causing the floor surface to be in constant seething
motion
with
dermestids scurrying about looking for food. While young bats falling
to
the
floor can be skeletonized in minutes, the greatest impact of dermestids
comes
from their waste byproducts, which, combined with water vapor, become
ammonium
hydroxide.

That free-tailed bats can thrive in this toxic atmosphere may be one of
the most
remarkable things about them. Concentrations of ammonia in free-tail
caves
can
quickly build to levels that are lethal to humans, but the bats survive
by
lowering their metabolic rates. Carbon dioxide then accumulates, both
in
the
bats' blood and in respiratory mucous, directly proportional to
increases
in
ammonia inhalation. The carbon dioxide neutralizes the ammonia in a
buffering
mechanism that protects the lungs.

Although concentrations of just 250 parts per million are highly
hazardous
to
humans, free-tails can filter out more than 97 percent of the ammonia
present
when inhaled at 1,130 parts per million and can still eliminate 73
percent
at
over 5,000 parts per million. Levels in their roosts, however, rarely
exceed
1,000 parts. Depending on the concentration of ammonia in a freetail
roost, the
bats' fur bleaches from its natural dark brown or grey to various
shades
of
reddish brown. In caves where there are no dermestid beetles, ammonia
buildup
does not occur.

EACH NIGHT, colonies leave their roosts to feed, emerging in great,
often
spectacular, columns. The most impressive flights occur after the young
begin to
emerge with adults in August and September. Many have likened the sound
of
thousands and thousands of wings beating the air to that of a
white-water
river.
Observers often feel a slight breeze created by the bats as they swirl
higher
and higher to gain altitude before forming vast undulating columns.
Flights from
Bracken Cave are so dense that they can be seen on both airport and
weather
radar screens miles away. Emergences of colonies of this size often go
on
for
hours.

Mexican free-tailed bats are designed for rapid, long-distance travel.
Their
exceptionally long, narrow wings are geared for relatively highspeed,
low-maneuverability flight in open areas. Even their short, velvety fur
appears
to be an adaptation to reduce drag, and their ear orientation appears
to
form
airfoils that contribute lift during flight. They have been clocked at
average
flight speeds of 25 miles per hour and as high as 47 miles per hour in
level
flight, but they can also attain speeds of over 60 miles per hour using
tail
winds.

Mexican free-tails normally emerge by sundown. Researcher Timothy
Williams
observed Bracken Cave bats with radar, concluding that most feeding
occurred
within 528 feet of the ground. He and his research team observed dense,
early-evening concentrations of flying insects within this range. Some
scientists speculate that the bats from Bracken, which have been found
flying at
altitudes of 6,600 to 10,000 and more feet, may also be feeding on
concentrations of migratory moths at these heights. And again, they may
be
simply catching high tail winds to speed travel to distant locations.
Little is
known about how far they travel to feed, but given how high and fast
they
can
fly, many likely go more than 50 miles in one direction each night.

Free-tails spend more time traveling and feeding each night than most
bats, in
part due to competition from large numbers of roost mates. They
typically
are on
the wing from dusk until dawn. Nursing mothers require at least twice
as
much
food as nonreproductive bats, especially as their pups near fledging.
At
such
times, researcher Thomas Kunz found that they may consume their body
weight
nightly.

If one assumes that the 20 million nursing mothers at Bracken Cave each
eat
their body weight of about 12.3 grams, a single night's consumption
easily
could
exceed 250 tons of flying insects. Their total ecological and economic
impact is
probably enormous. One study conducted near Carlsbad Caverns, New
Mexico,
determined that about half of the insects eaten were pests that had fed
on
alfalfa and cotton crops, the nearest of which were grown some 40 miles
away
along the Pecos River.

Mexican free-tails feed exclusively on flying insects, mostly moths,
flying
ants, and beetles, according to samples thus far reported. At the turn
of
the
century, Charles Campbell, the city bacteriologist for San Antonio,
Texas,
built
large artificial bat roosts to "control mosquitoes" [BATS, Summer
1989].
Some of
these tower-like structures were occupied by hundreds of thousands of
bats, and
many San Antonians swore by his success.

Although Campbell observed bats of unknown identity catching mosquitoes
in
the
area, there is no documentation that the free-tailed bats from his
artificial
roosts actually ate them. Given the high-speed, relatively
low-maneuverability
flight of free-tails, it seems unlikely that they would prey
extensively
on
mosquitoes. Bats, however, are highly opportunistic; the larger, also
fast-flying, hoary bat (Lasiurus cinereus) is known to home in on
mosquitoes
when they are abundant.

At dawn, the free-tails return to their roost in an event sometimes
said
to be
even more spectacular than evening emergences. Richard Davis and his
fellow
researchers observed flocks of thousands of bats each, first becoming
visible
4,900 to 8,200 feet above Bracken Cave. These high-altitude flocks
sometimes
flew past the entrance at speeds of almost 60 miles per hour before
turning
around and diving toward the entrance. Beginning about two hours before
sunrise,
small groups built up into a continuous diving stream, reaching the
greatest
density about 30 minutes before dawn. The first arriving bats came in
shallow,
zigzagging glides, but as flight density increased, they formed a
continuous
stream of individuals dropping out of the sky into the mouth of the
cave.
Each
was executing a rapid series of free falls with closed wings,
alternating
with
abrupt, brief wing openings to control speed and direction. Some groups
dropped
nearly 10,000 feet at speeds estimated to exceed 80 miles per hour.

AS SOON AS their young have become proficient flyers, many free-tails
leave the
major nursery caves of Central Texas. Once thought to be migratory
movements,
these August departures apparently are only local and are correlated
with
weather patterns, combined with the stress of overheating and
concentrated
gas
buildup in their caves. just before bats begin to leave Bracken Cave in
early
August, huge clusters roost within inches of direct sunlight in the
cave
entrance where fresh air is most available. These factors may also be
combined
with attempts to escape parasites that build up on roosts during the
nursery
period.

As large numbers of bats leave the cave, they begin appearing in groups
of
tens
to hundreds of thousands under highway bridges and in almost any other
available
place. During 1993, an extremely dry year in Central Texas, so many
free-tails
attempted to move under Austin's Congress Avenue Bridge that tens of
thousands
were forced to hang out in the open on the concrete pillars. With
three-quarters
of a million bats of its own, the bridge is the site of the largest
urban
colony
of bats in the world.

Additional groups of up to 500,000 each were reported beneath other
bridges that
year, and unprecedented numbers moved into parking garages, vacant
buildings,
and sports stadiums. But on the night when the first mild cool front
passed in
early September, many thousands of free-tails that had been roosting in
exposed
places apparently returned to Bracken Cave, which had by then been
purged
of hot
gases by the cool air. Although the emergence from Bracken had been
surprisingly
small for several weeks, it was extraordinarily large on the evening
following
the disappearance of the excess bats from the Congress Avenue Bridge,
some
60
miles away.

True southward migration of the free-tails appears not to begin until
October.
The vast majority of the U.S. population spends the winter mostly in
large
caves
of northern and Central Mexico. Populations living in California,
western
Arizona, Oregon, Nevada, and southwestern Utah apparently live in
roughly
the
same areas year-round, though seasonal movements among roosts are
common.
There
are two main migrations. Most of those from the Southwest migrate south
along
the Sierra Madre Occidental and the West Coast of Mexico at least as
far
south
as the state of Sinaloa. Free-tails from the Great Plains typically
travel
southward through

Texas and along the Sierra Madre Oriental into eastern and
south-central
Mexico,
some perhaps farther.

It is clear that major migratory departures in the fall are triggered
by
the
passage of strong cold fronts from the north. Large departures from
Bracken are
typically correlated with passage of extra-strong cold fronts arriving
in
late
October or early November. Departure dates can vary by several weeks in
different years, according to changing weather patterns. Not all of the
bats
leave at once, instead departing in several large groups at different
times.

Even among populations that migrate, not all bats leave. Several
thousand
have
been observed overwintering in Bracken Cave, as well as in concrete
crevices
beneath the Congress Avenue Bridge, and in old buildings in Austin.
Although
free-tails can enter torpor during inclement winter weather, they are
not
true
hibernators. During extremely cold weather, many die. It is unknown why
some
stay behind.

The longest proven migrations are of bats banded by Bryan Glass in
northwestern
Oklahoma and later recovered up to 1,104 miles south in Mexico. The
northernmost
area where he believed any of his bats could have overwintered was 480
miles
south in Texas. The original bandings were made at four caves less than
48
miles
apart, between which the bats intermingled. One bat was recaptured at
its
cave
of birth in Oklahoma after having completed eight migratory circuits.
Free-tails
typically return to their home areas, but for these long distance
travelers, a
home area may include caves over 100 miles apart.

All available evidence suggests that free-tails typically travel in
groups
at
all seasons. Richard Davis and fellow researchers recorded a
particularly
impressive spring arrival on April 22 at Frio Cave in Texas. At a time
when few
other bats had yet arrived, "several million bats hurtled down out of
the
night
within the space of ten minutes." They arrived at about midnight. Denny
Constantine, another researcher, believed that inexperienced travelers
arriving
at night could locate less familiar caves simply by listening for local
bats and
following them in. Traveling in groups certainly must increase the odds
that
some in the group will know the way.

Davis believed that migratory movements were rapid, crossing Texas in
one
or a
few nonstop flights, covering at least 290 miles a night. Given
knowledge
of bat
flight speeds with tail winds, migrating free-tails should be able to
cover that
distance in no more than five hours, perhaps substantially less,
depending
on
wind velocity. Such timing would ensure arrival at stopover caves at
optimal
times for following other bats in, if necessary, and allow for
unanticipated
delays due to bad weather.

WHILE FREE-TAILED BATS are among the more studied, what remains to be
discovered
about them may be even more fascinating than what we already know. Why
do
so
many fly so high? Are they simply catching tail winds to aid in rapid
travel to
distant locations, or are they actually feeding at such high altitudes?
How do
they navigate at high altitudes, given the fact that their echolocation
signals
reach little more than 100 feet and that cave entrances can be nearly
impossible
to see from even a few hundred yards? Bats are known to use celestial
cues, but
whatever cues they are relying on must work both night and day, since
flights
often arrive in midmorning.

Perhaps the most interesting questions of all involve the composition
and
role
of flocks. How do they form? Who leads them, and how do they know where
they are
going, or how early to leave to ensure arrival at a time when they can
maximize
feeding success? Are groups composed of roostmates that hang in close
proximity
to each other by day, or do they have some other means of getting
together
prior
to leaving the cave? With animals as fascinating as these, researchers
will be
pondering the answers to such questions for many years.

(Bio)
Merlin D. Tuttle is founder and Executive Director of BCI. Portions of
this
article are excerpted from his forthcoming book, Bats of North America,
to
be
published by University of Texas Press.

(Footnote)
* The project is thoroughly described in Bat Bomb, World War II's Other
Secret
Weapon by Jack Couffer, available in the BCI catalogue.



On Sun, 02 Nov 2003 03:48:49 GMT, "JNJ" opined:

(This I have to admit is surprisingly pleasant to hear when
considering
just
how bass ackwards most people here are. Hopefully they DO realize the
bats
are migrating OUT of the area for the cold season. JNJ)

************************************************* ***************
Bats Brought In To Battle Mosquitos
LAST UPDATE: 10/31/2003 10:51:04 PM

The Anderson Park District is taking unusual measures in the fight
against
West Nile. It is bringing in bats, in hopes the winged creatures will
gobble
up mosquitos, which are known to carry the virus. This comes after a
mosquito with West Nile was found over the summer in Kellogg Park,
leading
the District to cancel their Haunted Hike this year.

Puddles in the park were treated with chemical dunks to kill larvae,
and
mosquito magnets were also used to get rid of the adult insects. Seven
bat
houses, made by local boy scouts, have been put up in the park. Each
one
housing 30 bats, of 11 different species. Park District officials say
if
the
experiment works, more bat houses will be put up in other parks next
fall.

One bat can eat 500 of the insects in just one hour. But there's no
need
to
be afraid. Park officials say that bats' reputation of sucking blood
and
flying into human hair are simply myths. They only fly close to people
if
their exceptional radar and hearing show a bug nearby to eat.