Animal Ecology & Conservation

Donald Winslow, Zoology

25 January 2008

Ecology (Ernst Haeckel)

• An organism’s relationship to its biotic and abiotic environment.

• Ecologists study factors that affect spatial distribution and abundance of organisms.

Biological hierarchy

• Cell

• Tissue

• Organ

• Organ system

• Organism

• Population

• Community

Nine-banded armadillo

Ecological hierarchy

• Organism

• Population

• Community

• Ecosystem

• Landscape

• Biome

• Biosphere Agricultural corridor within forested landscape in southern Indiana.

A population

American coots (Fulica americana) at Lake Thunderbird. Photo by Zac Ottis

A community

Ruddy Ducks and Eared Grebes at Great Salt Plains Lake

Coast Live Oak forest at Camp San Luis Obispo, California

An ecosystem

(biotic and abiotic components interacting)

A landscape

Coastal oak woodland and chaparral at Camp San Luis Obispo in California

A biome

Sonoran desert near Phoenix, Arizona

Broad fields in ecology

• Physiological ecology

• Population ecology

• Community ecology

• Ecosystem ecology

• Landscape ecology

• Biogeography

Physiological ecology

• Energy budgets

• Endothermy – Metabolic thermoregulation (bird or mammal)

• Ectothermy– Behavioral thermoregulation (e.g. reptile)

Population ecology

• Demes and metapopulations

• Demographic parameters

• Population dynamics and regulation– Role of resources

• Metapopulation dynamics– sources & sinks

A metapopulation

Source

Sink

Demographic parameters

• Population abundance and density

• Age structure

• Sex ratio

• Growth rate

• Survivorship

Age structures of human populations in Afghanistan and Belgium

From Hickman, et al. 2006. Integrated Principles of Zoology, 13th ed., McGraw-Hill, New York.

Exponential and logistic models of population growth

From Hickman, et al. 2006. Integrated Principles of Zoology, 13th ed., McGraw-Hill, New York.

Community ecology

• Species interactions– Competition

• Niche, tolerance ranges, habitat

– Predation & parasitism• Models & mimics• Keystone species—starfish & mussels

• Species diversity

Ecosystem ecology

• Gross and net productivity

• Trophic levels and food webs

• Producers, consumers, decomposers

Conservation Biology

• Defining conservation biology

• Valuation of biodiversity

• Threats to biodiversity

• Solutions for conservation challenges

• Sustainability– Living in ways that do not degrade

resources on which future generations depend, allowing civilization to persist.

Defining Conservation Biology

• The natural world

• World ecosystems

• Biodiversity conservation

• History of conservation biology

Valuation of Biodiversity

• Extrinsic values– Economic uses of species– Medical uses of species– Genetic resources– Ecosystem services

• Intrinsic value

Threats to biodiversity

• Human population growth• Human industry and resource use• Extinction of species• Loss of genetic diversity• Habitat change• Overexploitation• Invasive species & disease• Climate change

Habitat change

• Habitat destruction

• Habitat degradation

• Fragmentation

Habitat destruction

• Primary cause of biodiversity loss

• 80+% of threatened species affected by habitat destruction or degradation

• A decrease in habitat availability decreases the number of breeding territories and thus population productivity.

Destruction vs. degradation

• Destruction: Changed to such an extent that one or more ecological populations can no longer use the habitat.

• Degradation: Habitat still used, but individuals have lower fitness and populations reduced viability.

Habitat fragmentation—loss of contiguity as well as area.

Neotropical Migrant Birds

Winter in tropics in Central and South America.

Breed in temperate North America during the spring & summer.

Long-term continental declines have been observed in a number of species.

Wood Thrush (Hylocichla mustelina) incubating

Hatching Wood Thrush nest next to regeneration opening

Breeding Bird Surveyhttp://www.mbr-pwrc.usgs.gov/bbs

Neotropical migrants are dependent on:

• Breeding habitat• Migratory stopover sites• Winter habitat• Therefore, long-distant migrants link the

ecosystems of the hemisphere, and

• They are vulnerable to threats in each of these habitats.

Threats on breeding grounds:

• Habitat destruction.• Habitat degradation.• Habitat fragmentation.• Brood parasitism by Brown-headed

Cowbirds (Molothrus ater).• Nest predation by various nest predators.• Agricultural pesticides reduce food

availability and poison birds.

Human land-use patterns affect the abundance, distribution, & activity of

cowbirds & nest predators

• Cowbirds feed in pastures, agricultural fields and lawns.

• Cowbirds and many nest predators

(e.g. Blue Jays, rat snakes, and raccoons) use forest edges.

Brown-headed Cowbirds (Molothrus ater)

• Do not build their own nests.

• Lay their eggs in the nests of other birds.

• Often remove a host egg from the nest.

• The host parents raise the cowbird young.

• Cowbird nestlings out-compete host young and sometimes push them from the nest.

Brown-headed Cowbirds (Molothrus ater)

Nests parasitized by cowbirds

Nest predators in Midwestern forests include:

• Blue Jays and crows.

• Snakes, such as the black rat snake.

• Large mammals, such as racoons and skunks.

• Small mammals, such as squirrels and mice.

• Many other birds and mammals may harm eggs and nestlings if given a chance.

Rat snake (Elaphe obsoleta) preying on Wood Thrush (Hylocichla mustelina) nest.

Edge Effects on Cowbird Parasitism

An “edge” is the border or transition between two habitat types.

• Agricultural edges

• Urban or suburban edges

• Roads

• Internal edges from clearcuts or maintained wildlife openings

Timber is extracted from Indiana state forests using individual and group selection techniques

• Individual selection—Individual trees are removed from within a harvest tract.

• Group selection—Small openings are created by removing groups of trees.

• Site preparation entails the construction and maintenance of roads, skid trails, and log landings.

• These methods generate high edge density.

Regeneration opening, Compartment 1, Tract 16

Acadian Flycatcher(Empidonax virescens)

• Breeds in eastern United States.• Winters in Central and South America.• Nests in mature forest, May-August.• Nest suspended from fork in branch, typically 3-

7 m high.• Clutch size usually 3.• Female incubates.• Both parents feed young.

Checking the contents of a Red-eyed Vireo nest.

Objective—Experimentally evaluate the effects of logging in Yellowwood State Forest on nest survival and cowbird parasitism level.

Hypothesis—Timber extraction decreases nest survival (by increasing predation) and increases parasitism.

Prediction—Nest survival will be lower and parasitism higher after logging than before, relative to values measured in unlogged sites.

Study Sites

• Nests in eight tracts in Yellowwood State Forest were monitored in 1995 & 1996. (Three were also monitored in 1994.)

• Four sites were logged between 1995 & 1996.

• The other four sites were close to rotation age but remained unlogged during 1996.

0

0.2

0.4

0.6

0.8

1

1995 1996

Year

OS

R

ControlTreatment

Overall Success Rate of

Acadian Flycatcher nests in Yellowwood State Forest

before (1995) and after (1996) treatment sites were logged.

Ratio of 1996 OSR ratio to 1995 OSR ratio: 0.460, p < 0.025 (one-tailed)

Treatment:Control 1.22 Treatment:Control 0.563

Proportion of Acadian Flycatcher nests parasitized before (1995) and after (1996) treatment sites were logged.

0

0.05

0.1

0.15

0.2

0.25

1995 1996

Year

Pro

po

rtio

n p

ara

sit

ize

d

Control

Treatment

Interaction effect: G = 3.49, df = 1, p = 0.031, (one-tailed)

Possible interpretations

• If factors responsible for between-year variation operate similarly in both sets of sites, the observed interactions between year and treatment may indicate logging decreases breeding success.

• Alternatively, site-specific processes at control tracts may have caused higher success in 1996.

Lessons from Indiana

• Where avian conservation is a priority in eastern deciduous forests, timber extraction should be limited until effects on nesting success are understood.

• Special attention should be given to monitoring breeding success of bird species that preferentially select edge habitats.

Solutions to conservation challenges

• Population level

• Species level—in situ and ex situ

• Ecosystem level—protection & restoration

• Landscape level

• Regional level

• Global level

• Conserving evolutionary processes

Sustainability

Sustainable practices are practices that can continue indefinitely—without depleting or degrading resources needed to continue.

Agriculture

Industry

Economy

Human relations