Wildlife TaggingWildlife Tagging

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Sampling WildlifeSampling Wildlife

It can be difficult to make an exact It can be difficult to make an exact count of the populations of animals, count of the populations of animals, birds, and fish that move around birds, and fish that move around their ecosystems.their ecosystems.

Sampling WildlifeSampling Wildlife

Scientists make their estimates of Scientists make their estimates of wildlife populations using wildlife populations using

capture-mark-recapture samplingcapture-mark-recapture sampling..

No animals are harmed in this sampling!

Sampling WildlifeSampling Wildlife

First, a sample is captured and First, a sample is captured and marked.marked.

Sampling WildlifeSampling Wildlife

There are many different kinds of capture There are many different kinds of capture methods, including:methods, including:

Aquatic dip nets (used in shallow water)Aquatic dip nets (used in shallow water)

Sampling WildlifeSampling Wildlife

There are many different kinds of capture There are many different kinds of capture methods, including:methods, including:

Aquatic dip nets (used in shallow water)Aquatic dip nets (used in shallow water) Mist nets (used for birds and bats)Mist nets (used for birds and bats)

Sampling WildlifeSampling Wildlife

There are many different kinds of capture There are many different kinds of capture methods, including:methods, including:

Aquatic dip nets (used in shallow water)Aquatic dip nets (used in shallow water) Mist nets (used for birds and bats)Mist nets (used for birds and bats) Helicopter darting (used for large animals)Helicopter darting (used for large animals)

Sampling WildlifeSampling Wildlife

There are many different kinds of capture There are many different kinds of capture methods, including:methods, including:

Aquatic dip nets (used in shallow water)Aquatic dip nets (used in shallow water) Mist nets (used for birds and bats)Mist nets (used for birds and bats) Helicopter darting (used for large animals)Helicopter darting (used for large animals) Live trapsLive traps

Sampling WildlifeSampling Wildlife

The marked individuals are released to The marked individuals are released to mix with the rest of the population.mix with the rest of the population.

Sampling WildlifeSampling Wildlife

Later, researchers capture a second sample. Later, researchers capture a second sample. Some of the second sample will be Some of the second sample will be marked and some will not.marked and some will not.

Sampling WildlifeSampling Wildlife

The total population N can be estimated The total population N can be estimated using the using the Lincoln indexLincoln index formula: formula:

n1 = number captured the 1n1 = number captured the 1stst time time

n2 = number captured the 2n2 = number captured the 2ndnd time time

m = number of marks found in the 2m = number of marks found in the 2ndnd sample sample

m

nnN

21

Sampling WildlifeSampling Wildlife

For this to work: For this to work:

The time span between the 1The time span between the 1stst and 2 and 2ndnd samples must be short compared to samples must be short compared to the lifespan of the animal.the lifespan of the animal.

The population must be The population must be closedclosed: : animals cannot immigrate (move in) animals cannot immigrate (move in) or emigrate (move out).or emigrate (move out).

Tracking WildlifeTracking Wildlife

Some tags are numbered or contain Some tags are numbered or contain radio transmitters and/or GPS radio transmitters and/or GPS receivers.receivers.

These allow researchers to study These allow researchers to study animals’ movements.animals’ movements.

Tracking WildlifeTracking Wildlife

We can looking at tracking data on We can looking at tracking data on www.movebank.comwww.movebank.com..