Habitat Selection

Habitat

Actual place where an organism lives and thrives, providing food, shelter, and mates for reproduction.

Habitat Selection

Behavior of choosing a place to live based on conditions, factors, other animals

Distribution

Final spatial arrangement of individuals and where they end up

Use

Where an animal went (its actual location)

Availability

What is accessible for animal to choose from a habitat

Selection

Use is not proportional to availability (using more or less than expected/available)

Preference

Animal selecting one habitat over another (what patch is chosen)

Quality

The survivability and reproductive success of an animal in a specific habitat

Rarely Habitat Selection Scale

Once in a lifetime decision for a habitat (natal area, home range, nest site, breeding area)

Seasonally Selection Scale

Few times a year based on breeding or migration for habitat selection

Daily Selection Scale

Everyday choices of habitat (where to hide, eat, rest)

Does preference = quality ?

No, animals can prefer a habitat that is actually bad for them (death)

Why is the cue an animal responds to (proximate) not the same as the evolutionary reason it matters (ultimate)?

Animals don’t understand their own evolutionary fitness they just respond to the cue
Example:

• Proximate (The Cue): A bird sees tall, dense grass and thinks, "I should build my nest here."

• Ultimate (The Reason): That tall grass actually hides the nest from snakes, which means more babies survive and pass on their genes.

What are Johnson's (1980) 4 Orders of Habitat Selection?

1. Geographic range (continent)

2. Home range (neighborhood)

3. Use within Range (What patches inside the home range)

4. Food Items (What specific items/microsites)

Why do some animals look picky for one selection over another

The scale changes on what counts as available.
Example:

• Not picky: Bear just lives in mountain forests not caring what valley or state it is in (1/2)

• Highly Picky: Bear selects berry bushes and avoids dry pine forests (3/4)

Habitat Quality 6 things to look for (and key thing to remember)

1. Food accessibility

2. Predation risk, (can I hide)

3. Competition (any bullies)

4. Climate (right shade, water, temperature)

5. Breeding site

6. Parasites/Disease

The best habitat for one might not be the best habitat for another

Judge Habitat

Animals rely on various cues and can predict if a habitat is suitable using physical, experienced, or social cues

Physical Cues

Vegetation, predators, temperature, food availability, water, light

Experience

Innate decision, where individual is born, developmentally shaped by others

Social Information

Conspecific action following species

Vegetation as a Cue (Bird)

Bird diversity is tied to foliage because they don’t care about species of tree just layering for food/nest building

Food Vs Safety

The best food can be the more dangerous option and have a trade off between food sources and safety because currency is gain - risk not gain alone

Case Study Bluegill Sunfish and Bass

Smaller sunfish rew less due to bass presence and larger ones didn’t care because they were in no danger and ate

How to measure habitat selection

Choice experiments where test options are equal, use GPS collars to ensure true use not just random points, actually measure if a habitat is increasing fitness for species because use tells what animals choose but fitness says if that choice was good

Selection Ratio

w = %used/%available
w > 1, used more than expected
w < 1 used less than expected
w = 1, proportional as expected

Ideal Free Distribution

Animals are free to go wherever they want and distribute based on resources in a patch so number of animals proportional to amount of food in patch (competiton makes the food per animal equal for everyone)

Stickleback fish and Mallard Ducks

Distributed themselves at a perfect 2:1 ratio to match 2:1 food source

Ideal Despotic Distribution

Dominant animals have access to resources causing an imbalance in resource distribution, with subordinates having limited access based on dominance hierarchy.

How can Density be misleading

Density may not accurately reflect resource availability or habitat quality because sinks can look crowded but reality animals are dying

Sources Haitat

Births > deaths with so many animals they spill to other areas

Sink Habitat

Death > Birth with animals only getting there because of immigrating from source but it’s declining

Ecological Traps

Cues animals have gives them misleading information when choosing habitat that leads to death (mayfly + asphalt)

Conservation Importance

Protect the source habitat not just sinks, not not build traps, use cues to trick endangered animals to colonize safely like nest boxes or decoys