#7 Habitat selection I

Habitat

The area where an animal or group of animal lives, including all resources and interactions, both biotic and abiotic, that affect survival and reproduction

• the sum total of the environmental factors, food, cover, and water, that a given species needs to survive and reproduce in a given area

What are the 5 scales habitat is described at?

• Broadest scale

• Region

• Habitat

• Local habitat

• Microhabitat

Broadest scale

• Biome/ entire ecoregion of continents 

  • A ton of variation within that area

• Coarse, general ecological patterns

• May describe a species’ entire distribution or an entire biome

Region

• More specific ecological patterns

• Area use/patch selection

• Home to a species’ home range or one or more populations

Habitat (scale)

• Part or all of a population, but rarely entire species’ range

• Even more specificity (tides, weather, vegetative community)

• The level we tend to perceive things at

Local habitat

• Specific sub-set of an area where the species can occur

• Where certain stages occur at

Microhabitat

• A “habitat within a habitat” that possesses different or unique characteristics

• “A nest site”

  • Why do they choose to nest here opposed to other areas in the same location

Which habitat scale is this at?

Broadest scale

• EX: Nearctic boreal wetlands

Which habitat scale is this at?

Region

• EX: Yukon-Kuskokwim delta wetlands

Which habitat scale is this at?

Habitat

• EX: Yukon delta estuarine marsh

Which habitat scale is this at?

Local habitat

• EX: this pothole marsh

Which habitat scale is this at?

Microhabitat

• EX: This specific patch of tundra grasses, forbes, and lichens on the edge of this pothole

What are some Habitat characteristics you should look at, and what are the differing scales?

• Vegetation: 

  • thousands of hectares 

• Water level management: 

  • hundreds of hectares

• Fine-scale microhabitats: 

  • square meters

How do we measure the + and - of a habitat use?

by looking at and measure the Welfare factors and the Decimating factors

What are some Welfare factors?

accessibility of food, water, and shelter

What are some Decimating factors?

• predation, disease/parasites, dangerous weather, human interference, etc.

  • Competition 

  • Social factors

  • Habitat change/stability (long term)

How do you Identify habitat types?

Often vegetation is the dominant factor in how we categorize habitat

• Cattails? 

  • Habitat for Marsh wrens, dragonflies, waterfowl, and fish

  • Is it fair to call “cattails” a habitat type?

    • It depends on the scale of habitat you need to look at

    • yes → microhabitat

    • no → anything broader

Habitat quality

the ability of a habitat to provide conditions and resources appropriate for individual and/or population persistence

What do we measure when we are interested in a certain habitat and what other factors in the environment affect it?

Quality 

• Pollution 

• Diversity

• size/connectivity 

• Productivity

• Reproductive success**

What are 2 other big types of habitat quality?

• Resource provision

• Source/sink dynamics

Why is Resource provision a big type of habitat quality?

• Production/density of food or other welfare factor

• Ability to provide for the needs of resident animals

• Change in biomass

  • lead to a relationship between the amount of food in an area

  • how good the quality of the environment is for them

Why is Source/sink dynamics a big type of habitat quality?

• Areas that are growing = high quality

  • Failing to reproduce/dieing off = sink = poor quality

• Quality assessed by rates of population growth in a given habitat

  • Underlying assumption– higher quality habitat supports more beavers

  • Can be helpful in identifying important population strongholds

What is one method to measure habitat quality?

Wetland Rapid Assessment Technique (WRAP)

• Developed to produce a single number to assess wetland ‘quality’

• Highly generalized, but this can cause drawbacks to applicability!

• Many sub-models and different approaches, (California has CRAM)

What are some pros of the Wetland Rapid Assessment Technique?

• Compare other habitat and wetlands to see which one to conserve 

• Works on a larger scale

  • Wetlands quality across broader scales

What are some cons of the Wetland Rapid Assessment Technique?

• The more specialized the wetland becomes the harder it is to assess it

• Habitats are also rapidly changing 

• The technique is too generalized

Habitat use

Where animals/ populations are found

What do we want to seek to understand about habitat use?

• mechanisms for selection

  • Pursue welfare factor? 

  • Avoid decimating factors?

  • Limited or rare resources

    • Availability of resources can flip the selection of habitat that is utilized

What does SLOSS stand for, and how is it related to habitat use?

• Single Large Or Several Small

• refers to a conservation debate about whether one large habitat or several small habitats is better for biodiversity and habitat support

What is one correlation regarding SLOSS and wetlands?

Small wetlands appear to accumulate rare and endemic species faster

• though studies are mixed by taxon

Habitat selection

The process by which organisms select habitat across available areas relative to use

• Operates across scales

  • Can be dictated by radically different needs

How does habitat use differ from habitat selection?

• Use

  • refers to where animals are actually found or distributed across habitat types

• Selection

  • Use relative to availability

  • indicates whether animals are choosing certain types more than expected by chance

What is the underlying assumption of habitat selection theory?

That animals select habitats in a way that increases their fitness — meaning survival and reproduction

Habitat “preference”

an inference made from observed habitat selection — it's the idea of what animals might “like” or favor among available options

• Will to use the place

Why is the term "habitat preference" considered imprecise?

• often implies cognitive choice (what animals want), which is hard to prove and measure.

  • selection is more objective and testable

Does habitat selection imply animals are consciously choosing habitat?

Not necessarily.

• While preference may imply cognitive choice

  • Selection can occur through innate behavior (genetically driven) or learned behavior (from experience)

  • without conscious decision-making