Wildlife Management Techniques Exam #2

Encounter Rate

probability of a live animal entering the observed sample in time t

Capture Rate (Mark-Recapture)

probability that an individual is captured during a given time period in an actual trap or net

Recovery Rate

probability that a hunter will, during a given time period, shoot a marked animal- shot and recovered animals cannot be released to the wild because they are dead. “Recoveries” are a special type of mark-recapture data

Re-sighting Rate

probability that an animal marked with colored or numbered tags will be seen by a person and recorded (i.e., not in a trap) during a given time period

Establishing Capture History (Mark-Recapture)

• 110010: six occasions

• captured on 1st, 2nd, and 5th

How many time to sample a population

at least 2 times or more

Capture Probability (p)

probability (p) that an individual is captured during a given time period in an actual trap or net

Closed Population Type (Mark-Recapture)

• assume no births, deaths, immigration, or emigration during the study

• normally short time periods (depends on species)

• used to estimate population size

Open Population Type (Mark-Recapture)

• assume that births, deaths, and movement occur

• usually longer studies

• used to estimate survival and movement rates

Cohort

number of marked animals released in time period t

Captured In All Periods

1-1-1

Captured In First Two Periods

1-1-0

Captured In First and Third Periods

1-0-1

Only Captured In First Time Period

1-0-0

Lincoln-Petersen Capture Model

• capture animals in 1st occasion, mark them, capture (or recover) animals in second occasion

• Notation

  • n₁ = animals captured, marked and released

  • n₂ = animals captured in 2nd sample

  • m₂ = number in n2 that were previously marked

  • N = population (unknown)

• works well with large samples

Theory of Lincoln-Peterson

% of marked animals remains the same in both capture periods (1 and 2)

• sample in 2nd period gives insight to reality

Lincoln-Petersen Assumptions

• Capture probabilities are equal for all animals at each occasion

  • p₁ and p₂ do not have to be the same

  • Re-sighting an animal = “second capture”

• Marking does not affect p₂

• No loss of marks between occasions

• All marks at time 2 are reported

• Random sample of population each time

Immobilization

induction of chemicals/drugs to capture or restrain animals

Anesthesia

use of drugs or other substances to temporarily induce a loss of feeling or awareness. Allows clinical procedures to be done with a minim of pain, discomfort, and side effects to the animal

Analgesia

the loss of sensitivity to pain (painkillers)

Akinesia

loss of motor response (movement) due to paralysis of motor neurons

Requirements of large animals that cannot be captured to use remote injection

• must have adequate muscle mass- to absorb impact of the dart

• must have adequate circulation- to rapidly absorb and cause rapid effects of drug

When administering remote injection to shoulder region

avoid joint

When administering remote injection to hindquarter region

avoid head of femur

Capture Myopathy

stress from being captured

Effects of Capture Myopathy

Stress results in lactic acid release into
bloodstream
– Changes pH in blood, which can result in cardiac
failure immediately in some cases
– If animal survives immediate condition...as heart
muscle dies over the next week, it releases
myoglobin (protein, binds oxygen and iron)
– Myoglobin damages kidneys, lungs, and liver—
death can result in delayed fashion

Sedative

depresses the central nervous system dulling conscious awareness; stimuli are received but brain normal response is decreased

Anesthetics

alleviates the perception of pain

Muscle Paralytics

fully conscious, but cannot respond

Tranquilizers

used in conjunction with other drugs (sedatives, anesthetics, muscle paralytics)

Neuromuscular Blocking Agents

• act on the junction between nerve and muscle

• paralyzes, but feel pain

• not ethical to use

Central Nervous System Agents

• act on the brain and spinal cord

• produces anesthesia, loss of consciousness

• ethical to use

Opioids (Carfentanil)

Morphine-like, highly potent in small volumes, loss of consciousness, may be reversed (but may “recycle”)

Cyclohexamines (Ketamine)

Rapid immobilization with altered consciousness (not loss), may move tongues and blink. Cannot be reversed (have to wait to recover)

Neuroleptics (Diazepam (valium), Xylazine)

Tranquilizers (calmness and relaxation), do not cause loss of consciousness at safe doses, often used in combination with opioids and cyclohexamines

Drugs Birds Get

gas anesthesia, ketamine combinations for surgeries

Drugs Amphibians Get

gas anesthesia

Drugs Reptiles Get

ketamine alone, gas

Non-Invasive Marking Methods

• bands

• neck collars

• external color marking

Invasive Marking Methods

• radioisotopes/chemical markers

• ear tags

• PIT (passive integrated transponders)

• tattoos

• ear notching, shell/toe/scale clipping

When is Chapman modification used

when you have small samples of mark-recapture

What process provides CJS - capture history

mark-recapture

Used in Finding Known Fate

radio telemetry

Collar/Necklace

mostly for mammals (necklace for birds). Collar needs to be tight enough to not go over neck, but not too tight to cause skin irritation, allow for growth, movement

Backpacks

used mostly with birds; loops around breast and belly. Use of backpacks has slowed to a large degree, or have been modified

Harness Loops

used mostly with small birds; loops around legs

Subcutaneous Anchors

placed under skin with “anchor”; anchored in place. used with birds, mammals

Modified Leg Bands

used mostly with birds with relatively long legs

Glue-on transmitters

used with birds, bats, mammals, reptiles

Implants

surgically implanted into animal; requires vet, immobilization (birds, mammals, reptiles and fish)

What methods are used to adjust for imperfect data?

• Mayfield Survival Method

• Open population

• Right-censoring

• Kaplan-Meier method

What do you collect in the Mayfield Survival Method?

- track exposure days
- determined fate (and date)
- produces daily survival rate (4 decimal places)

What is the key assumption of Mayfield Survival Method?

all subjects have constant survival during observation --> allows for staggered entry

What are the Kaplan-Meier method assumptions?

- Keeps track of individuals over interval times
- Mortality not constant over interval times
- Mortality rate constant per individual

What is the Kaplan-Meier method?

way to collect survival rates of units of time with corrections to error

Reducing Error Polygons

• Take 45 and 90 degree angles on transmitter

• Get closer to transmitter (without disturbing animal)

• Move to different locations as fast as you can

• Get to higher ground- hear transmitter better

Exposure Days

the number of days the animal, nest, or young is exposed to a possible mortality event

What is staggered entry?

subjects are not required to enter the study at the same time to the sample

Home Range

contains essential requirements of life: food, water, cover; area traversed by the individual in its normal activities of food gathering, mating, and caring for young

What is the importance of home range?

• useful for managers and biologists for planning conservation areas

• useful as a statistic of animals under different treatments

• practical for hunting/trapping animals

Utility Distribution (UD)

the relative intensity or probability of use of areas by an animal, or what is the probability that an animal will use a given point in space in a given period of time

Core Area

Subset of the range excluding occasional outlier excursions; or, the UD with disproportionately high use compared to the rest of the range

Territory

defended part of animal’s home range

How to obtain home range data?

• telemetry (most common)

• multiple recaptures

• marks on animals (natural or not)

Minimum Convex Polygon

Create “95% utility distribution” by removing 5% of the OUTER-most points that reduces area the most

What are ways/estimators to analyze home range?

• minimum convex polygon

• bi-variate normal (parametric)

• grid

• harmonic mean

• kernel

Advantages of Minimum Convex Polygon (hulls)

• simplest

• history of use (compare to others)

• flexibility of shape

• ease of calculation

Disadvantages of Minimum Convex Polygon (hulls)

• size increases with number of locations

  • cannot compare to others

• does not indicate interior use of home range

Parametric Method: Normal Distribution Assumes:

• animal’s activity concentrated in center of home range

• probability of occurrence decreases with distance from center (bell-shaped curve)

• Home range ALWAYS elliptical- single center of activity

Grid Cell Count Advantages

• avoids assumptions of underlying distribution (e.g., normal distribution)

• can determine areas of high use and eliminate outliers

Grid Cell Count Disadvantages

• can miss areas that may be important in home range

• analyses and comparisons are very sensitive to cell size

• same sample size issues as MCP

Harmonic Mean

scoring the landscape

• based on the distribution of animal locations- not statistical distribution

• uses comparison of a gridded map to the animal locations to derive activity contours

• each grid point gets a score for how close it is to animal movements

• home range shapes can be irregular

The Kernel Estimator

• value of the utility distribution (UD) at a landscape point

• the more times an animal is near given site on the landscape, the probability that the animal uses the site increases

Habitat Selection Order (First)

location of physical or geographic range of a species

Habitat Selection Order (Second)

location of home range within a study area or geographic range of species

Habitat Selection Order (Third)

habitat components within a home range

Wildlife Community Assessments

focuses on ecosystem health rather than individual species/population

Habitat Use

quantity of resource used in a fixed period

Habitat Availability

amount of each resource accessible for use

Habitat Selection

disproportionate use of, a habitat relative to its availability

Log Ratio (Compositional Analysis)

a modification of a simple ratio (fraction):

• Calculated as:

  • Log₁₀ (% use / % available)

  • Note: Log₁₀ (1.0) = 0

    • Negative log ratios indicate less use than
      availability

    • Positive log ratios indicate more use than
      availability

    • Zero equals no selection or avoidance

    • So, “log” used to ‘center’ on 0, rather than 1

Species Diversity

the diversity of the community measured by species richness and evenness

Species Richness

the number of species in a community

Species Evenness

the distribution of individuals among species in a community