Download - Sunapee School

Frank B. Gill
and Mr. Baker
Ornithology
Third Edition
Chapter 21
Conservation
Part 4 – Conservation by Design
Copyright © 2007 by W. H. Freeman and Company
Conservation Biology sets
priorities and integrates objectives
with large-scale plans of habitat
management. The goal is to protect
and restore habitat in an effort to
maintain healthy ecosystems with
broad spectra of plants and animals.
The design of nature reserves must
take into account bird movement
and their seasonal needs. Corridors
allow movement between reserves,
which helps maintain genetic
diversity. Designs and locations
must be able to adapt to changes in
climate - such as those due to
global warming.
Populations of plants and animals
tend to occur in patches - local
populations. Local populations that
interbreed are grouped into
"metapopulations“.
If a local population disappears,
other members of the
metapopulation may move in and
restore it. Managing populations
must take two factors into account:
1. The probability of extinction of
populations.
2. The importance of maintaining
genetic diversity.
Small, fragmented
populations lose genetic
diversity (due to
inbreeding or chance).
This reduces survival and
fertility, such that the
population may not be
able to recover.
Population viability model for the
Florida Scrub Jay. Computer
simulations show that the
probability of short-term
extinction of an isolated set of
territories decreases with the size
of the starting population (see
numbers). Populations with only
a single family group territory are
likely to disappear within 50
years, but populations with 100
territories will last for centuries.
Greater Prairie Chicken populations in Illinois dropped to the extent that
conservation biologists imported birds from larger, more diverse western
populations to maintain the genetic diversity.
Populations trends and fertility in a remnant population of Greater Prairie Chickens in
southeastern Illinois. Counts of breeding males (bottom line) declined steadily after a brief peak
in 1972, until extra males were introduced from other, larger populations. Genetic diversity and
egg-hatching rates (top line) declined in this small population, but then rebounded after birds
from other populations were introduced in 1990.
Human activities such as cutting forests or converting grassland to
cropland divide areas of habitat into smaller fragments. Small size and
extensive edges of fragments leads to...
• increased predation
• limited space for foraging and other activities
• invasion by exotic species
• reduced nest success
• reduced survival of adults
Dark areas are
forested.
Forest fragmentation in Missouri – nonforested (left) and forested (right) landscapes.
Forest fragmentation in N.Am. leads to higher rates of brood parasitism
(laying eggs in someone else's nest to reduce your cost of reproducing
and raising young) by Brown-Headed Cowbirds. Cowbird eggs tend to
hatch sooner than the eggs of the host bird, and the cowbird chicks will
push other eggs and chicks out of the nest.
INBU – Indigo Bunting
OVEN – Ovenbird
WEWA – Worm-Eating Warbler
KEWA – Kentucky Warbler
Songbird nesting success
increases with distance (10
categories from 0 to 123m)
from the forest edge, where
nest parasitism (by BrownHeaded Cowbirds) is greatest.
Parasitism is highest within 100-200m of the
forest edge. The interior is relatively safe, so
larger chunks of habitat are safer than smaller
ones. Small fragments tend to be population
sinks - places where local populations die out
quickly.
Minimum critical size studies in the
Amazon rainforest showed the
following...
• Local landscapes should
include some forests larger
than 1000 hectares. These
larger fragments can
supply birds to smaller
fragments to ensure
genetic diversity.
• Corridors allow birds to
travel from fragment to
fragment, aiding
diversity. They also allow
young birds to
disperse. Forest corridors
only need to be 100-300m
wide to be effective.
Natural disturbances, such as floods and fires, are a key part to keeping
habitats vital. Healthy ecosystems include a variety of habitats, in
different stages of recovery. Without this, there would be less habitat
diversity, supporting less bird diversity.
Before the colonization of N.Am., one-half of the continental U.S.
burned every 1-12 years due to fires started accidentally by lightning or
deliberately by Native Americans. Many habitats require regular burning
in order to maintain themselves. This is especially true of grasslands fire favors the growth of grasses, while discouraging the woody plants
that would naturally take over due to succession. Young grasslands
provide thick groundcover for nesting and a greater diversity of insect
prey.
Regular (in many cases, seasonal) flooding...
• creates backwater lakes and habitats
• replenishes vital nutrients
• resets plant succession on new soils
Floodplain habitats are threatened by dams, channels, levees and other
human attempts to control/minimize flooding.
Florida Scrub Jays live only in the scrub habitats of central
Florida. These habitats are renewed by regular fires (ever 8-15
years). When fires were suppressed by humans, the Scrub Jay
populations declined due to competition from Blue Jays and predation by
hawks and snakes. When the habitats were burned, Scrub Jay
populations rebounded for a while, then began to decline - in anticipation
of the next burn.
Grasslands were originally grazed on by bison,
antelope, and elk. More recently, they are grazed by
domestic livestock. Overgrazing creates deserts, but
moderate grazing and the rotation of livestock can
help maintain healthy grassland. Birds such as
Horned Larks and Montezuma Quail benefit.
In the US, commercial harvesting of trees for lumber causes more
disturbance of habitat than natural processes do. As an area is cut, it then
begins a series of successional stages in the process of recovery. Each
stage accommodates a different set of species with specific habitat
preferences. As the area matures, the species present change.
As this area grows in, it will be
colonized first by Winter
Wrens, Eastern Bluebirds, and
Northern Flickers.
Within two to three years,
species such as Mourning
Warblers, Common
Yellowthroats, and Swainson’s
Thrushes will move in.
About half of Neotropical
migrants that breed in
hardwood forests prefer early
stages of succession.
The shifting forest mosaic model. Forestry cutting of trees creates a variety of successional
stages in the landscape. Different shades denote four stages of forest age from young to old. The
stages “move around” over time as the forest grows and is cut in different years. Ideally, a full
complement of plant and animal species will colonize each stage.
Spotted Owls rely on old growth forests of the Pacific Northwest. As
these areas have been logged, the Spotted Owl habitat has
declined. Fragmentation allows more competition from larger Barred
Owls, and more predation by Great Horned Owls. Programs to protect
habitat for Spotted Owls have been put in place.
To focus their resources on areas of
greatest need, conservation
biologists have identified "hot
spots" - places in the world that are
under threat and have the highest
amounts of biodiversity. There are
three main factors that define a "hot
spot"...
• Largest number of total
species.
• Highest number of
threatened/endangered
species.
• Most endemic species (not
found anywhere else on
Earth).
Identified hot spots include...
• the tropical Andes of South America
• the Amazon River Basin (S. Am.)
• Atlantic Coastal Forest of S. Am.
• Guyana Highlands (S. Am.)
• the Himalayas
• the Rift Valley of Africa
More recently, the Important Bird
Areas (IBA) program was
established to protect a worldwide network of sites that stabilize
bird populations and their
essential ecosystems.
The IBA network includes federal
wildlife refuges and other
protected public lands, as well as
private and local community
lands.
So far, about 3,000 sites have been
identified in the Western
Hemisphere - with plans to grow
to about 8,000 sites.
Thus far, there are 15
IBAs in NH. There is a
link to their website on
the eBoard!
Community support is vital to the success of any conservation
movement. Thus, programs must take into account economic and social
variables, as well as biological ones.
Local pride is often the key to public support. An endangered parrot, the
Jacquot, was saved when conservation programs rallied the people of the
island of St. Lucia. The Jacquot is now the island's national bird and its
population has nearly doubled.
The Conservation Movement
The excesses of the 1700's and 1800's led to the beginnings of the
conservation movement in the late 1800's. The American Ornithologists
Union was founded in 1883, followed by state Audubon Societies and
federal agencies such as the U.S. Bureau of Biological Survey.
The movement was supported by the writings of famous authors of the
time, such as Ralph Waldo Emerson, Walt Whitman, John Burroughs,
and John Muir.
Emerson
Whitman
Burroughs
Muir
1887 - Fannie Hardy and Florence Merriam founded the first Audubon
Society at Smith College in Massachusetts. The goal was to get people
on campus to stop wearing bird feathers.
1896 - Harriet Hemenway founded the Massachusetts Audubon
Society. The goal was to discourage ornamental use of wild bird feathers
and to protect birds.
1934 - Rosalie Edge purchased 1400 acres on Hawk Mountain in PA,
and hired a warden (Maurice Broun) to protect the hawks passing
through this key part of their migration route. The goal was to protect
hawks and gain public support by encouraging hawk watching. Hawk
Mountain now maintains the world's longest and most detailed record of
raptor migration. The millionth raptor was logged on October 8,
1992. This database was used to uncover the connection between DDT
and raptor mortality rates. It was also used to track population recovery
when DDT was outlawed.
The lookout at Hawk Mountain near Reading,
Pennsylvania.
Several environmental crises launched the modern environmental
movement and motivated Congress to pass key environmental laws.
•1964 - The Wilderness Act
•1969 - The National Environmental Policy Act &
the Environmental Protection Agency
•1970 - The Clean Air Act
•1972 - The Clean Water Act
•1973 - The Endangered Species Act
•1974 - The Safe Drinking Water Act
President Nixon's administration (1969-1974) accomplished more
significant environmental legislation than any before or since - with the
possible exception of Theodore Roosevelt (1901-1909).
Various local and national nonprofit organizations grew to engage the
public. Today, there are more than 1,000 independent bird clubs, bird
observatories, coalitions, and Audubon chapters in North
America. Birdlife International is a coalition of national bird
conservation organizations worldwide.
In 1986, the US, Canada, and Mexico developed the North American
Waterfowl Management Plan (NAWMP). The goal was to protect
millions of acres of wetlands and meet population goals for 32 species of
ducks, geese, and swans.
In the 1990's, two more organizations arose...
• Partners in Flight (PIF) was a coalition of government and
nongovernment agencies, corporate leaders, and academic
professionals. The goal was to protect populations of
Neotropical migrants.
• The North American Bird Conservation Initiative (NABCI)
expanded the work of PIF to include "all birds, all habitats".
Citizen science is research done by people from every level of society in
collaboration with scientists. The oldest example of citizen science in
the world is the Christmas Bird Count, which was started by Frank
Chapman in 1900, in which volunteers from around the US and Canada
report on how many birds/species they observe over the Christmas
holidays.
A "birder" is defined as someone who "closely observed or tried to
identify birds around the home and/or took a trip a mile or more from
home for the primary purpose of observing birds."
There are an estimated 46 million birders (age 16 and
up) in the US. On average, they are well educated, earn
above-average incomes, and belong to several
conservation organizations. They range from beginners
who can identify only a few species to experts who keep
life lists of species seen.
Chapman
Birding provides economic support for communities and governments, as
well.
In 2001, US birders and wildlife watchers spent an estimated $24 billion
on binoculars, bird food, camp equipment and other items; and another
$7 billion on travel.
This generated about $85 billion in economic output and $13 billion in
state and federal income taxes.
Birding Ethics by the American Birding Association
Everyone who enjoys birds and birding must always respect wildlife, its environment, and the
rights of others. In any conflict of interest between birds and birders, the welfare of the birds and
their environment comes first.
1. Promote the welfare of birds and their
environment.
• Avoid stressing birds or exposing
them to danger: exercise restraint and
caution during observation,
photography, or recording/filming.
• Limit the use of recordings and other
methods of attracting birds. Never
use such methods in heavily birded
areas or for attracting any threatened
or endangered species.
2. Respect the law and the rights of others.
• Do not enter private property without
the owner’s permission.
• Follow all laws, rules, and regulations
governing the use of roads and public
areas.
3. Ensure that feeders, nest structures, and
other artificial bird environments are
safe.
• Keep dispensers, water and food clean.
It is important to feed birds continually
during harsh weather.
• Maintain and clean nest boxes
regularly.
• If you are attracting birds to an area,
ensure that they are not exposed to
predation from cats or other domestic
animals or to dangers posed by
artificial hazards.
4. Group birding, whether organized or
impromptu, requires special care.
• Continued…
Birding Ethics by the American Birding Association
Everyone who enjoys birds and birding must always respect wildlife, its environment, and the
rights of others. In any conflict of interest between birds and birders, the welfare of the birds and
their environment comes first.
4. Group birding, whether organized or
impromptu, requires special care.
• Respect the interests, rights, and skills
of fellow birders, as well as those of
people participating in other
legitimate outdoor activities.
• Freely share your knowledge and
experiences. Be especially helpful to
beginning birders.
• If you witness unethical birding
behavior, assess the situation and
intervene if you think it prudent.
Please follow this code – distribute it and teach it to others.
In 1953, American naturalist Roger Tory Peterson and British
ornithologist James Fisher journeyed across North America and surveyed
the bird species that lived there.
They documented their journey in the book Wild America (1955). Fisher
concluded the book with the following quote…
“Never have I seen such wonders, or met landlords so
worthy of their land. They have had, and still have, the
power to ravage it; and instead they have made it a
garden.” [Fisher, pg. 418 in Wild America]
Fifty years later, author/naturalist Scott Weidensaul took another look at
North America and made the comment…
“I found the continent changed – for the better in some
places, for the worse in others. Yet the land, the rugged
heart of natural America, retains an essential
timelessness... Ours is still, at its core, a wild country.”
[Widensaul 2005, pg. xx]
Chapter 21 – the last chapter in your Ornithology book – ends with this
paragraph…
“Our knowledge of birds and our appreciation of them can
assure their future and ‘the rugged heart of the planet.’
That has been the theme of this book. Each of us can make
a difference. Please start now.”
[Gill 2007, pg. 684]
End of
Part 4.