Habitat Selection

Habitat Selection?

Some Terms… Habitat – Place where an organism lives Home Range – Area that an organism occupies during its life Territory – An area occupied and defended by an organism Migration – The long distance movement, and subsequent return, from one location to another.

Why choose a certain habitat? Why do you live where you do?

Why do animals choose a certain habitat? Genetics vs. Early Experience

Why do animals choose a certain habitat? Food Ideal Free Distribution (Manfred Milinski)

Genetics and Early Experience Males and Females raised on Cellulose or Cedar bedding Males generally prefer what they are raised on. Females generally prefer cedar by at least the third day. Older females switch to cedar faster than younger females. Males influenced by early experience whereas females are more influenced by genetics.

How do animals pick a habitat: Genetics and Early Experience

Factors: Early Experience

Foraging Behavior Barn Owl What to eat?

More on Patch Ecology Risk-Sensitive – Animals that can tell one patch from another patch Risk-Prone: Animals willing to take risk Risk-Averse: Animals not willing to take the risk

Changes in the strategy: Are animals risky or safe? “Risk Prone” willing to take risks “Risk-averse” avoid risk and will take the safer option.

Changes in the strategy: Caraco et. al. and Yellow-Eyed Juncos Birds choose 1) variable (0 to 6 seeds) or 2) constant (3 seeds) Done at 1°C and 19°C. Birds are risk-averse at 19°C, risk-prone at 1°C.

Risk-Averse animals will go here Risk-Prone animals will go here 1st hour 1st hour 2nd hour 2nd hour Patch #1 Patch #2

Why do animals choose a certain habitat? Food Food and the Ideal Free Distribution (Manfred Milinski)

Why do animals choose a certain habitat? Your tax dollars (or mine) at work! Competitive Unit Model

Territories An area actively defended by an animal Why Defend? Anolis Not Food! Temperature and Predator Avoidance

Territories Anolis lizard arrive quicker on experimental plots and use the site more. Lizards LEARN where good habitats are by watching others. E is experimental where they removed a male from an already occupied territory. C is a control where they tried to mimic what a good habitat might be like (HOWEVER, maybe they don’t know what a good habitat is like). Figure A is amount of time spent on the different sites, while the other graph is how quickly they arrived to experimental/control.

Territories - Conditional Pied Wagtail Eats insects washing on shore. Lots of food, allows Satellites (help defend territory….have less knowledge of food pattern) Byproduct Mutualism in under certain circumstances

Territories - Changing Side-Blotched Lizard Defend Rocky Territories Less Rocks, larger territories More Rocks, smaller territories more competition. Average 1 female in both 20

Territories – Defend for Mating Some animals might defend territories for mating purpose Antlered flies – defend territories on rotten logs

Migration When territories or habitats change drastically over time, what do you do? Migration – Long distance movement and subsequent return from one location to another.

How do you know where to go? Different animals have different abilities to tell where they are: Piloting – Recognizing landmarks Compass Orientation – Able to tell specific directions

How do you know where to go? Various Sensory Abilities: Visual Cues Stars Magnetism

Migration – Using the Sun Raised in captivity and then released: b) first 5 minutes of autumn migration a) Clock shifted butterflies fly west c) Natural population fly south P445. (A) clock shifted birds fly west. B) Laboratory raised butterflies who were raised on a normal light-dark cycle for autumn fly south (C) Butterflies from natural populations fly south. A is the experiment and B is the control that shows you can raise them under artificial conditions that mimic natural sunlight conditions. Normal condition = fly south in the fall (as winter approaches). Clock shifted (A)….they think that summer is approaching and they are moving towards a north migration.

Migration – Using Earth’s Magnetic Field 31

Green Sea Turtles 32

Green Sea Turtles 33

Migration – Using Stars Emlen funnel (add to words) Ink on feet mark footprints. Left (spring), Middle (fall) Right (when night sky is obscured.

Factors Effecting Migration Some populations migrate, others do not. Leapfrog effect A does not leave. Further north, the further south they travel. Why? Might miss food, might not return quick enough for breeding territory.

Factors effecting migration Sometimes migrates Older, more dominate males migrate less. Juveniles make the best of what they can, migrate until larger? Researchers not quite sure.

Factors effecting migration Birds with low fat reserves (A) Birds with high fat reserves (B)

Habitat Selection in Pill Bugs Types of Movements: Taxis: Directed movement towards/away from a stimulus Kinesis: Random movements

Choice Chambers

Thing to think about? What do they eat? What eats them?