AGLS 6502

An endangered species is a species whose population has been so reduced as to make the species susceptible extinction in the near future (through environmental, demographic or genetic stochasticity).

Why has Endangered Species Management become so important?

Loss of biological components of value to humans:
Consumptive Use Values

Environmental Goods (eg. food, medicines)

Non-consumptive Use values Climate control

Oxygen recharge

Option values
Existence values
Bequest Values

What is Biodiversity?

Genetic diversity:
- The number of genes that have more than one allele (polymorphic genes)
- Number of alleles for each gene (heterozygosity)

Species diversity:
Definitions of what a species is:

Biological species concept
Based on reproductive isolation.

Number of Species described: 1.8 million

Estimated of Number of species: 5 million to 10 million (30 million?)

There are several measures for ecosystem diversity:

richness
evenness
uniqueness

Ecosystem diversity at different landscape scales:

Alpha diversity (equivalent to species diversity)
Beta diversity (change of species diversity across an environmental gradient)
Gamma diversity (rate at which new species are added as replacements to system)

~ Ecosystem components:

Species composition Niches and Adaptive types

~ Ecosystem processes:

Energetics (trophic interaction)
Mutualisms
Succession
Nutrient flows

10.3 The Ecological Context of the Current Mass Extinction

The Geological-Time View

5-6 Mass extinctions
Changes in Physical environment
Rate of loss 1 spp/ 1000 yrs. (by 2000)

The Biodiversity Crisis:

Current Rates of species loss:
75 spp/ day in tropical forests alone
1 spp/hour

The Moral context of the Biodiversity Crisis.

The Nature of Being and the Rights of Species to Exist.

Intrinsic value
Human stewardship responsibilities
Spiritual and aesthetic value of biodiversity

The Evil Quartet

1. Over-exploitation

Exploitation at rates higher than MSY account for about 1/3 of all species currently endangered

2. Introduced Species (Exotic Species)

Competitive advantage (Purple loosestrife)
Disease transmission (Avian Pox on Hawaiian Crow)
Predation (Brown tree snake)
Important for island ecosystems

3. Habitat loss and fragmentation

Currently the # 1 cause of species losses
Edge effects

4. Ecosystem stress and cascading effects.

biomagnification
cultural eutrophication
global climate change

10.4 Characteristics of Small Populations

Typically, small populations are susceptible to environmental, demographic and genetic stochasticity.

Demographic characteristics

The Population bottle neck
The Allee effect
Metapopulation dynamics and presence of critical demographic thresholds
Stochastic concerns (Skewed sex ratios & Unequal genetic contributions)
The Minimum viable Population: (99% survival in 1000 yrs.) The Minimum Dynamic Area

Genetic Characteristics

Loss of genetice variability: 1/(1/2Ne)
Founder Effect (loss of genetic variability, represent a small sample of original population)
Genetic Drift (loss of environmental flexibility)
Inbreeding depression
Outbreeding depression

Which Species are Vulnerable?

Species with small geographic range:

e.g. island species (Kakapo/New Zealand)

Species with one or a few populations sizes:

e.g. White tailed Sabre-wing (Tobago & Venezuela)

Species with small populations:

e.g. large predators or extreme specialists

Species which have populations in decline:

Species with low population densities:

e.g. South American macaw species

Species which require large home ranges:

e.g. jaguar

Species with large body size:

e.g. Siberian tiger

Species which are poor dispersers:

e.g. Caribbean parrot species

Seasonal migrant species

e.g. North American migrant songbirds

Species with little genetic variability:

e.g. cheetah

Species with specialised niche requirements

e.g. Hawaiian Drepanididae

Species found in stable environments

e.g. tropical forest epiphytes

Species which form temporary aggregations:

e.g. Great Auk

Species hunted or harvested by people:

e.g. passenger pigeon

10.5 Management Tools for Endangered Species Recovery

Ex-situ Conservation

Zoos/Aquaria & seed/gene banks
Roles in endangered species recovery:

Public education
Wild population augmentation
reintroduction source
Sanctuary for Orphan Species

Techniques:

Cross-fostering
Artificial insemination
Embryo transfer

Limitations:

Cost (eg. captive elephansts cost 50 times more to manage
than wild ones)
Number of species: (of 274 mammal species in zoos, only
10% have viable populations)
Loss of adaptive behaviors
Not applicable to all species

ln-situ Conservation

Includes:

Habitat management/ecological restoration
National Parks/Biosphere reserve
Management of competitors & exotic species
Management of human environment

Requires info on:

genetic
physiology
behavior
morphology
demography
distribution
biotic interactions

10.6 A Few Tools for Population Performance

Monitoring game species populations can be done through the following:

Use of Hunter Provided data
~ Catch-effort techniques as a measure of population performance
~ Hunter returned data the simplest source for these data

Use of catch effort relationships in wildlife management

10.7 A Case Study in Game Species Management - Trinidad and Tobago

Over-exploitation of game populations in a common theme in the process of human transformation of the landscape. Thus, in the Caribbean as much as 80 percent of the terrestrial mammals have been extirpated or driven to extinction due to human over exploitation.

This process is being repeated again with the fauna of Trinidad and Tobago

Catch effort analyses suggest that large-mid sized mammal populations on the islands were in steep decline over a 4 year period due to over-hunting.

The species studied showed populations 10 to 30 times lower than one would expect (i.e. lower than K).

Management Approaches in Trinidad and Tobago

No mechanisms for limiting "take": number of individuals harvested
Hunting effort can only be regulated by restricting season length, no other traditional techniques can be applied (e.g. limiting the number of hunters).
Current season length 5-6 months
Mandatory Data-return Forms (MDF)- post 1990.

Status of Game Populations and Habitats

Most species densities well below 0.5K
Current harvest rates are well above the level of sustainable yield (see attached tables)
Extent and condition of habitats in the islands remain un-quantified

Public acceptance of control measures

Questions and considerations to be asked:

1. Public support:

What methodologies can be applied with public support?

Is a public education program required?

2. Legal considerations:
Is the species a protected one? Which control techniques are legal?

3. Available techniques for harvesting:
Lethal measures:

e.g. Shooting, poisoning, snap traps

Non-Lethal measures:

e.g. relocation, taste aversion techniques, frightening screening/fencing, habitat modification, change in cultural practices

4. Cost:
Determining acceptable losses.
Cost-benefit ratio and wildlife damage control.
Are there socially acceptable levels of pest losses?

5. Timing:

When is action appropriate?

Wildlife damage control: A step-wise approach

Problem definition
Consideration of the ecology of the species
Deciding on control methods
Evaluation of success of control techniques.

10.8 Suggested Readings

Primack, R.B. 1995. A Primer in Conservation Biology. Sinauer Associates Inc. Massachuseffs.277pp.
Meffe, G.k., and C.R. Carroll. 1997. Principles of Conservation Biology. Sinauer Associates. Inc. Massachusetts. 729pp.
Soule, M. E. Conservation Biology: the Science of Scarcity and diversity. Sinauer Associates. Inc. Massachusetts.