Ornithology Final

Habitat loss and habitat modification effects on habitat

Loss of area and modification of spatial structure, including fragmentation.

Habitat loss and habitat modification consequences

Favors the same winners over and over, especially human commensals, and leads to homogenization of wildlife communities.

Climate Change Impact on Surface Temperatures

Surface temperatures increased 0.7ºC during the 20th century and may increase another 1.1 to 6.4°C during the 21st century.

Climate Change Associated Effects

Rising sea levels, altered precipitation patterns, and increased frequency/intensity of severe weather events.

Behavioral response to global warming: Shifts in distribution

Birds have shifted ranges 19 km northward in the past 20 years in Great Britain.

Behavioral response to global warming: Shifts in timing of breeding season

Tree Swallows began breeding 9 days earlier in 1991 than in 1959.

Behavioral response to global warming: Disruptions of biotic interactions

Some species shift timing of seasonal events while others don’t, leading to disruptions of biotic interactions.

Audubon Societies (late 1800s)

Originally established to protect egrets and herons.

National Wildlife Refuge System

Established in 1908; contributions of hunters to conservation including the Federal Duck Stamp.

Migratory Bird Treaty Act (1918)

Originally established to control market hunting.

Rachel Carson’s “Silent Spring” (1962)

Raised awareness of the impact of pesticides and pollution on wildlife.

Endangered Species Act (1973)

Most important legislation for protection of declining flora and fauna.

Brown Pelican cause of decline and reason for recovery

Pesticides; natural recovery(after DDT banned)

Bald Eagle cause of decline and reason for recovery

Pesticides; natural recovery and reintroduction (after DDT banned).

Peregrine Falcon cause of decline and reason for recovery

Pesticides; reintroduction (after DDT banned).

California Condor cause of decline and reason for recovery

Loss of prey; captive breeding and reintroduction.

Whooping Crane cause of decline and reason for recovery

Loss of habitat; natural recovery and captive breeding.

What you can do for bird conservation

Support conservation organizations, participate in citizen-science projects, keep cats indoors.

What you can do in your yard for bird conservation

Reduce or eliminate use of pesticides and herbicides, plant native plants, remove invasive plants, attract hummingbirds, prevent bird collisions, provide cover, control lighting, add water features.

Interspecific competition

Occurs when two or more species compete for a shared, limiting resource.

Interference competition

One species aggressively excludes others from a resource; a direct interaction between individuals of competing species.

Exploitation competition

One species depletes a resource more efficiently than another; an indirect interaction between individuals of competing species.

Competitive exclusion

Two species with identical niches cannot coexist, leading to extinction or niche partitioning.

Niche partitioning (Ecological displacement)

Shifts in distribution, habitat use, diet as an ecological response to competition.

Character displacement

Shifts in morphology as an evolutionary response to competition.

Species-area relationship

Species richness increases with area; S = cAz.

Alpha (α) richness

Number of species at a given point or site; within-habitat diversity.

Gamma (γ) richness

Number of species in a given region; regional diversity (among many habitats).

Beta (β) richness

Rate of change in species composition across sites (habitats); between-habitat diversity. (β = γ / mean α)

Stability-time hypothesis

Species richness is an equilibrium between rates of speciation and extinction.

Unique resources hypothesis

Tropical regions have higher species richness due to additional resources not found in temperate zones.

Niche-partitioning hypothesis

High species richness leads to intense interspecific competition, favoring specialization and niche packing.

Equilibrium theory of island biogeography

Species richness on an island is a dynamic equilibrium determined by immigration and extinction rates.

Ivory-billed Woodpecker

A bird species highlighted in conservation efforts, image courtesy of David Allen.

Human-caused bird extinctions (prehistoric)

Likely >9000 species extinct due to habitat loss, invasive species, and direct exploitation. Example: Elephant bird.

Vulnerable bird species (prehistoric extinctions)

Large species and island species are particularly vulnerable due to small population sizes, predator naivety, ground-nesting habits, and sometimes flightlessness. Example: Moa.

Human-caused bird extinctions (historic)

At least 131 species extinct worldwide, 90% on islands. Causes include habitat loss, invasive species, direct exploitation, pollution, and climate change. Example: Dodo.

Extinctions of Hawaiian Birds

Original land bird fauna of 99 species; 50 extinct after Polynesian colonization, 17 after European colonization; 32 remaining, 19 critically endangered. Example: Bishop’s O`o

Labrador Duck

Range: Atlantic coast of northern U.S. and Canada. Extinct due to hunting, last seen in 1875.

Eskimo Curlew

Range: Varied. Extinct due to market hunting and destruction of migratory stopover habitat. Rarely seen after 1890s.

Great Auk

Range: North Atlantic. Extinct due to hunting by humans, last seen in 1844. Flightless alcid, ecological equivalent of penguin.

Passenger Pigeon

Range: Eastern United States. Extinct due to market hunting by humans, last seen in 1914. Was once the most abundant bird in the world.

Carolina Parakeet

Range: Eastern U.S. north to Great Lakes. Extinct due to hunting as agricultural pest and habitat destruction, last seen in 1918. Only parrot in North America north of Mexico.

Bachman’s Warbler

Range: Southeastern United States. Extinct due to destruction of habitat (bottomland hardwood), last seen in 1980s in Cuba. Possibly a canebrake specialist.

Ivory-billed Woodpecker

Largest woodpecker in United States. Possibly extinct, with recent purported sightings in Arkansas (2004) and Florida (2005).

Declining Bird Populations (North America)

Many grassland birds (mostly short-distance migrants) and some forest birds (mostly long-distance migrants), and shorebirds are declining.

Threats to Mainland US Bird Species

Habitat alteration, invasive species, disease, overharvesting, pollution, and cowbird parasitism contribute to endangerment.

Sources of Bird Mortality (North America)

Human-associated mortality is caused primarily by cats, hunters, windows, and cars. (Excluding habitat loss)

Threats to Hawaiian Birds

Habitat destruction by invasive plants and feral animals, and avian malaria are major threats. Nearly all native birds are endangered.

Causes of Avian Declines (Worldwide)

Habitat destruction and modification, invasive species, toxic chemicals, collisions with man-made objects, predation by pets, and hunting are major causes.

Bird Conservation

Conservation measures need to be taken before birds become threatened or endangered.

Ecology

The study of interactions between a living organism and its environment, including other living organisms.

Population

All individuals of one species in one place.

Population Size

Key attribute of a population, refers to the abundance or number of individuals.

Abundance

Number of individuals in a population.

Density

Number of individuals per unit area in a population.

Communities

All individuals of all species in one place; a collection of populations.

Species Richness

Number of species in a community.

Evenness

Distribution of individuals across species in a community.

Species Composition

List of species in a community.

Population Ecology

Understanding the mechanisms that regulate population size.

Exponential Growth Model

A model of population growth assuming there are no limits to growth; dN/dt = rN.

Logistic Growth Model

A model of population growth that assumes there are limits to population growth, represented by the environmental carrying capacity (K); dN/dt = rN(1-(N/K)).

Carrying Capacity (K)

The maximum population size that an environment can sustain given available resources.

Abiotic Factors

Factors that limit population growth imposed by the physical environment (e.g., weather).

Biotic Factors

Factors that limit population growth imposed by ecological interactions with other biological species (e.g., competition, predation).

Density-Independent Factors

Factors that limit population growth where the effect does not vary with population size (e.g., weather).

Density-Dependent Factors

Factors that limit population growth where the effect does vary with population size (e.g., competition).

Territoriality

A density-dependent factor that regulates population size, where territories are finitely compressible.

Intraspecific Competition

Competition between individuals of the same species.

Interspecific Competition

Competition between individuals of different species.

Direct (Interference) Competition

A form of competition where individuals directly interact and prevent others from accessing resources.

Indirect (Exploitation) Competition

A form of competition where individuals deplete a resource, making it less available to others.

Semelparity

A strategy where organisms invest all their energy in one large reproductive effort.

Iteroparity

A strategy where organisms invest their energy in many small reproductive efforts.

Lifetime Reproductive Success

The total reproductive output of an organism throughout its life.

Clutch Size

The number of eggs in a single nest.

Life History Strategies Tradeoffs

Trade-offs in resource allocation between longevity (survival) and fecundity (reproduction).

Resource Allocation Trade-off

Allocation of resources between survival and reproduction, affecting lifespan and reproductive rate.

K-selected Species

A slow life history strategy characterized by slow development, low annual fecundity, and long life, exemplified by the Northern Royal Albatross.

R-selected Species

A fast life history strategy characterized by rapid development, high annual fecundity, and short life, exemplified by the White-throated Sparrow.

Annual Fecundity

The number of young fledged per year.

Number of Reproductive Years

The number of reproductive years depends on age at first breeding, potential longevity, and age-specific mortality rate.

Potential Longevity

The length of life an organism could potentially reach.

Age-Specific Mortality Rate

Rate of death within a specific age group.

Annual Fecundity Determinants

The number of nesting attempts, clutch size, and number of young successfully raised to fledging.

Indeterminate Clutch Size

Environmental conditions determine exact number of eggs, within some determinate range

Food Limitation

Clutch size is adjusted to maximum number of nestlings that the parent or parents can successfully raise (due to food limitation).

Seasonality of Food Resources

Clutch size adjusted to seasonality of food resources.

Nest Predation

Clutch size adjusted to risk of predation rates

Lifetime Resource Allocation

Clutch size adjusted to optimal balance of resource allocation between current and future reproductive efforts

Brood Parasitism

A reproductive strategy where one species lays its eggs in the nests of other species.

Cooperative Breeding

A social system in which individuals help raise offspring that are not their own.

Parental Care

When one or two parents care for the eggs and young in most species of birds.

Intraspecific Brood Parasitism

Brood parasitism within the same species.

Interspecific Brood Parasitism

Brood parasitism between different species.

Facultative Interspecific Brood Parasitism

Interspecific parasitism of related species, such as Black-billed and Yellow-billed Cuckoos.

Obligate Interspecific Brood Parasitism

Brood parasitism where the parasite always relies on another species to raise its young (e.g., Cowbirds, Honeyguides, Old World cuckoos).

Egg Mimicry

Adaptation of brood parasites where their eggs resemble the host's eggs.

Experienced Host

Host species that have evolved inherited responses to brood parasites.