…as more individuals are produced than can possibly survive, there must be a struggle for...

…as more individuals are produced than can possibly survive, there must be a struggle for existence.

C. Darwin

Wildlife Mortality

• Why is understanding wildlife mortality important?

• What are the types of mortality?

• How do different types of mortality interact?

• What affects wildlife mortality?

• What is differential vulnerability?

Wildlife Mortality

• What is the difference between additive and compensatory forms of mortality?

• Why do we consider harvest as a special type of mortality?

• Why do we harvest wildlife?

• How do harvested and unharvested wildlife populations differ? Why?

Wildlife Mortality

• What is a harvestable surplus?

• How and why do we regulate the harvest?

• Why is hunter and trapper education so important?

• What about anti-hunters?

• Who cares?

Wildlife Mortality

• 1 - survival

• Patterns of survival– Slope of line

• Importance– Populations– Emotions

Age

Sur

vivo

rshi

p

Type II

Type I

Type III

← K-selected

← r-selected

Wildlife Mortality

• Normal v. abnormal– Management implications

(U.S Fish & Wildlife Service)

Wildlife Mortality

• Types– Starvation & Malnutrition– Disease & Parasites– Accidents– Predation– Exposure– Harvest

Natural

Natural can still be abnormal!

Wildlife Mortality

Harvest

Death

Disease & Parasites Starvation & Malnutrition

AccidentsExposure

Predation

Wildlife Mortality

• Proximate v. ultimate factors– Implications

Wildlife Mortality

• Mortality Rates– %/time, #/time, or ind/ind*time (d)

• Daily• Seasonal• Annual

– Sex/age class

Wildlife Mortality

• Density-dependence– Types

Population Density

Mor

talit

y R

ate

B

C

A

…starvation outside the breeding season is the most important density dependent factor in wild birds….

D. Lack

Wildlife MortalityStarvation & Malnutrition

• What’s the difference?

• What types of wildlife starve to death? Die of malnutrition?

• How common are these forms of mortality?

• Welfare or Decimating Factors?

• Proximate or ultimate factor?(U.S Fish & Wildlife Service)

(U.S Fish & Wildlife Service)

Wildlife MortalityStarvation & Malnutrition

• Artificial feeding v. habitat improvement

• Management implications– We failed as managers?

– Good intentions with bad results

(U.S Fish & Wildlife Service)(U.S Fish & Wildlife Service)

Wildlife MortalityStarvation & Malnutrition

• Artificial feeding v. habitat improvement– Baiting & ethics

• Management implications– We failed as managers?

Disease in a wildlife population is rarely a simple, one-cause, one-effect situation. Usually it is the product of profound changes in the environment.

L. Karstad

Wildlife MortalityDisease & Parasites

• Pathology

• Etiology

• Parasitology

• Epizootiology– Enzootic– Epizootic

• Welfare or Decimating Factors?

Wildlife MortalityDisease & Parasites

• Causes of disease– Intrinsic flaws

• Hereditary or congenital diseases

– Deficiency diseases*– Exogenous poisons– Trauma– Tumors– Living organisms*

Wildlife MortalityDisease & Parasites

• Types of disease– Toxicoses (poisons)

• Organophosphate & carbamate pesticides• Organochlorine pesticides & PCB compounds• Aflatoxicosis• Lead poisoning• Oil toxicosis

Wildlife MortalityDisease & Parasites

• Types of disease (living organisms)– Avian Cholera– Tularemia– Brucellosis– Sylvatic Plague– Duck Virus Enteritis– Aspergillosis– Botulism– Leptospirosis– Anthrax

– West Nile Virus– Lyme Disease– Rabies– Distemper– Avian Pox– Salmonella– Tuberculosis– Hemorrhagic Disease– Chronic Wasting Disease

Wildlife MortalityDisease & Parasites

• Types of parasites (living organisms)– Gizzard worms– Nasal leeches– Gastrointestinal nematodes– Lungworms– Liver flukes– Boophilus– Psoroptes spp.

– Tapeworms– Meningeal worms– Nasal bots– Ascarid roundworms– Giardia spp.– Trichomoniasis– Mange

Wildlife MortalityDisease & Parasites

• How common are these forms of mortality?

• Habitat affects

• Density-dependence

• Population regulation

Wildlife MortalityDisease & Parasites

• Control & management– Direct– Indirect

• Use as biological control agents– European rabbits in Australia– Red imported fire ants

Wildlife MortalityDisease & Parasites

• Wildlife diseases & people– Rabies– Lyme disease– West Nile virus– Avian influenza– Chronic wasting disease (CWD)

Wildlife MortalityDisease & Parasites

• Management implications

Accidental mortality is of greater concern if the affected wildlife population is small, so that a few accidentally killed animals constitutes a fairly large proportion of the population.

J.A. Bailey

Wildlife MortalityAccidents

• Types– Collisions with objects– Drowning– Choking– Falls– Entanglement and entrapment– Research

• IACUC

• Welfare or Decimating Factor?• Normal? Natural?

Wildlife MortalityAccidents

• Prevalence– >3,500,000 birds/yr killed by striking windows

(Banks 1979)

– Wildlife-vehicle collisions(Schaefer et al. 2003)

Wildlife MortalityAccidents

• Management implications– National Safety Council (2000): 520,000

animal-related accidents resulting in 100 deaths and 4,000 injuries.

• Deer/auto collision cost about $2,000-8,000 per claim for repairs and injuries.

– Romin and Bissonette (1996): >78,689 deer/auto collisions/yr with $124,092,553/yr in damage

– Wildlife populations?

All living things are destined to die and be recycled as a part of the flow of energy through the life community. Which is to say, a creature must feed, and sooner or later it will be fed upon.

D.L. Allen

Wildlife MortalityPredation

• Types of predation (Leopold 1933)

– Chance– Habit*– Sucker list*– Starvation– Sanitary

• Depredation?

• Jaguar case study

(U.S Fish & Wildlife Service)

Wildlife MortalityPredation

• Carnivory– Cannibalism

• Welfare or Decimating Factor?

Wildlife MortalityPredation

• Protective refugia– Density-dependence– Threshold of Security

XX

Wildlife MortalityPredation

• Predator behavior– Numerical response

Prey Density

Pre

dato

r D

ensi

ty

Wildlife MortalityPredation

• Predator behavior– Functional response

Prey Density

# P

rey

Eat

en/P

reda

tor

Wildlife MortalityPredation

• Importance of predators– Communities

• Stability & diversity

– Prey• Buffer species• Cycles & regulation

– “Thinking like a mountain”

Wildlife MortalityPredation

• “Abnormal” predation– Cats

• 1 cat: 60 birds & 1600 small mammals in 18 months (Schafer 1991)

• >19,000,000 songbirds & 140,000 game birds killed/yr in Wisconsin

• Feral & pet cats in the U.S. each year (USFWS study)

– <20.7 billion mammals– <3.7 billion birds

Kenneth M. Gale, www.forestryimages.org

Wildlife MortalityPredation

• Predators & humans– Livestock, pets, game species, etc.

– Opinions split or indifference• Fear, economics, pets, & lack of understanding of value

Wildlife MortalityPredation

• Predator control– Methods

• Cost• Effectiveness

– Attitudes• Coyotes (USFWS 1978)

Extremely Acceptable

Not Acceptable at All

Slow-acting poisonsSteel leghold traps

DenningAerial gunning

Shooting from the groundFast-acting poisons

Pay ranchers not to raise livestock

Pay ranchers for losses

Birth control

Repellent chemicalsGuard dogs

Nonlethal Methods Lethal Methods

Wildlife MortalityPredation

• Predator control– Does it work?

• Coyotes• Wolves• Bears

• Quail, mallard ducklings, moose, sea turtles ….

– Effects on communities• Thinking like a mountain!

Wildlife MortalityPredation

• Management implications– Normal– Abnormal

– Predator control

Wildlife MortalityPredation

• The case of quail– Have we failed as mangers if we must control predators

to have quail to hunt?

– Literature review– Weak or lack of data– Habitat management = predator management– IPM– Sympatric, parapatric, & allopatric– Proximate v. ultimate factors– Irruptions

Reasonably healthy bobwhites may perish through imprisonment by drifting snow.... Exposure to cold, high winds and snow may kill reasonably healthy bobwhites…. Although drifting and undue cold is an infrequent occurrence, it appears worthy of the game manager’s attention, especially in the provision and strengthening of cover.

T.G. Scott

Wildlife MortalityExposure

• Extreme cold or heat, blowing snow, or intense rain or hail– Direct & indirect effects of weather

• DD v. DI factor• Periphery of range

• Food, cover, & water– Proximate v. ultimate

• Welfare or Decimating Factor?

Wildlife MortalityExposure

• Density-dependent?– Protective Refugia

• Management implications

XX

Wildlife Mortality

• Effects vary– Sex– Age– Season– Behavior– Region

– Northern Bobwhite example

Northern Bobwhite Survival

• Annual survival: 5-30%– Higher in the South– Males > females– Lower in first year birds

• Seasonal differences– Spring-Summer (breeding season): 13-51%

• South: fall-winter > spring-summer• North: spring-summer > fall-winter

Northern Bobwhite Production• Nest success

– 32-44%

• 5-10% of adults killed

• Losses– Predation

• Mammals & snakes*• Ants

– Weather

Northern Bobwhite Production

• Broods– 14 days for thermoregulation & flight

• 30-40% survival– Predation– Weather

– 15-30% survival through 30 days

Quail Predation

• Primary cause of death– Adults

• Avian predators: 40-65% of mortality– During nesting & migration

• Cooper’s & sharp-shinned hawks in the SE

Quail Predation

• Mammalian predators– Nesting & winter (north)

• Snakes– Nesting

• Fire ants– Chicks