Strategies, Decisions, and Preferences - Habitat Use

<Niche> ecological role of a particular species in an ecological community - Fundamental vs. realized; Presence/absence of a species; dispersal: may not have reached the habitat; abiotic determinants: weather conditions, soil, climate; biotic determinants: interactions with other organisms, predation, competition, disease, social factors; <Habitat> any part of the biosphere where a species can successfully live and reproduce; Space: The unlimited three dimensional expanse in which all material objects are located. Distribution and behavior of individuals or species contingent on spatially explicit references.

Strategies, Decisions and Preferences in Behavioral Ecology: confer an adaptive advantage with success measured as <Fitness> Reproductive Success, the probability that an animal of a particular genotype and phenotype will manage to foster reproductively successful offspring. Natural selection will favor individuals that use habitats in which the most successful offspring can be raised. May involve a balance of considerations: e.g., Herring gulls; Variables to consider: resource limitations; spatial and temporal distribution of the resource; variation in resource quality; number of competitors that attempt to control a resource; Predation pressure, etc.

• Habitat preference as a closed developmental system: many invertebrates, crayfish. Host plant preference in bladder grasshoppers. Poor response to rapid environmental change and human impact, e.g. Karner blue butterfly (Lycaeides melissa samuelis) depends on lupine (Lupinus perennis) as its sole larval food source. Species with highly fixed, genetically programmed habitat selection may require considerable time to evolve mechanisms for the selection of a new habitat
• Habitat preference as an open developmental system:
  • habitat imprinting: many migratory vertebrates, such as salmon
  • tradition: mountain sheep, greylag goose migration
• <Dispersal> Ecological process affecting distribution, and genetic process affecting geographic differentiation and variation; leaving an area of birth or activity; largely a short range effort; Colonization - long range dispersal. Stay in the safety of home: little danger but competition may reduce reproduction or Disperse and take chances: high mortality but high payoffs. Natural dispersal: e.g. Cattle egrets or Intended and unintended aid in dispersal by humans: e.g. European starling, house sparrow, Africanized honeybees
• Descriptives for Spatial Distributions: Are distributions random, clumped, dispersed? Describe distribution with: minimum polygon, bivariate normal, spatial autocorrelation, contiguous clustering, or non-parametric utilization distribution (UD)
• Use of Space
  • <Ideal Free Distribution> The relative number of foragers in each patch should match the relative amount of resource obtained there (except with incomplete information or inter-forager interference). Individuals should distribute themselves among habitats so that every individual maximizes its net rate of return. Costs and benefits may depend on how many other users are already using the resource. applies to food, mates, etc.
  • <Homerange>: area which an individual, pair, or group occupies or regularly returns to
  • <Core Area>: area of heaviest use, may center on a resource, i.e. nest, water source, food source
  • <Territory>: any defended area; area of more or less fixed boundaries from which rival conspecifics are excluded through Aggression (self-preservation, protection of the young, or resource competition)
  • <Lek>: a communal mating area in which individuals hold small territories solely for courtship and copulation

Reading Assignment

• Chapter 14: Habitat selection

Links of Interest

• Habitat Requirements of Lupine and the Karner Blue Butterfly
• Control of Migratory Locusts