What is habitat?


We all know what habitat is, right? It’s a fundamental concept that underpins a lot of the work we do in ecology. But how do you define it? How would you explain it in conversation with a colleague?

the habitat of an organism is the place where it lives

http://media.kids-myshot.nationalgeographic.com/2012/04/4f9f37c34b76bBrookes_NYC_Trip_062_large_medium.JPG
http://media.kids-myshot.nationalgeographic.com/2012/04/4f9f37c34b76bBrookes_NYC_Trip_062_large_medium.JPG

This week I’ve been reviewing literature on habitat use by feral cats and sought to distinguish between the terms  habitat use and habitat selection. I came across this neat little paper by Paul Krausman (1999), which provides some good context on the meaning and use of different habitat terminology. Importantly, we see that habitat is species specific and scale dependent.

habitats are the resources and conditions present in an area that produce occupancy… it is the sum of the specific resources that are needed by organisms

We therefore know that habitat is the cumulative resources needed by a species for survival and reproduction. But what is habitat use, and how does it differ from selection?

Habitat use is just that, an animal using habitat. Whether it be for feeding, nesting, protection or resting.

Habitat selection (and preference) is more complex. This concept evaluates whether a species actively prefers or avoids certain types of habitat in the landscape.

habitat preference is the consequence of habitat selection, resulting in the disproportional use of some resources over others

Evaluation of habitat selection is a hierarchical process coined by Johnson (1980), and many papers use compositional analysis to evaluate second- and third-order habitat selection.

Second-order selection evaluates how home ranges are selected from those available across the landscape, while third-order selection describes how different habitats within the home range are used.

From the work that I’ve been doing I’ve learned that it’s important to make the distinction between habitat use and selection. Habitat use is valuable for describing which parts of the landscape a species uses, but to be able to make judgements on the relative importance of different habitat types, and preference or avoidance of them, measures of habitat selection are required.

Johnson DH (1980) The Comparison of Usage and Availability Measurements for Evaluating Resource Preference. Ecology 61(1), 65-71

Krausman P (1999) Some Basic Principles of Habitat Use. In ‘Grazing Behavior of Livestock and Wildlife.’ (Eds K Launchbaugh, K Sanders and J Mosley) pp. 85-90. (University of Idaho: Moscow, USA)

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