Tag Archives: resource

Using Yesterday’s Models for Today’s Conservation

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Image Credit: US Fish and Wildlife Service Headquarters, CC BY 2.0, Image Cropped

Are polar bear habitat resource selection functions developed from 1985-1995 data still useful? (2019) Durner et. al, Ecology and Evolution, https://doi.org/10.1002/ece3.5401

The Crux

Ecologists often attempt to predict where species are using the spread of the resources that the species depends upon. This is done because often it’s simply easier to monitor the resources than the species. Resource selection functions (RSFs) are a tool which use the likelihood of a resource being used to predict a species distribution. However, if the landscape the resource is found in changes drastically, a resource selection function may start to be less useful.

In the early 2000s, using data collected in the 80s and 90s, US scientists developed RSFs for polar bears, a species which has regrettably become the poster child for the survival of the Arctic ecosystem. Even back then, the bears’ preferred habitat was receding. Now, with human-driven climate change severely reducing sea ice and markedly altering the bears’ habitat, this week’s authors wanted to know how well those RSFs work nowadays.

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Hvorfor er dyr hvor de er?

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Image Credit: Endre Gruner Ofstad, CC BY-SA 2.0

Guest post by Endre Grüner Ofstad. English version here.

Use, selection, and home range properties: complex patterns of individual habitat utilization (2019) Endre Ofstad et al., Ecosphere, 10(4), https://doi.org/10.1002/ecs2.2695

Det essensielle

Stedene man finner dyr omtales gjerne som dyrets habitat. Habitat er et relativt vagt begrep. Hvor individ oppholder er som regel et utfall av en rekke vurderinger: hvor finner en mat, hvor unngår man rovdyr og hvor finner man noen å parre seg. Individ avveier blant disse for å maksimere hvor mange avkom de kan tilføre fremtidige generasjoner (også kalt for ‘fitness’).

Når vi skal vurdere hvilke habitat dyr befinner seg i så jobber vi som regel med habitatseleksjon. Habitatseleksjon er hvor mye et habitat blir brukt i forhold til hvor tilgjengelig det er, dvs. hva er den relative sannsynligheten for at et dyr vil bruke et habitat hvis det får muligheten. Hvor mye tid et individ velger å bruke (eller tettheten av individ) i et habitat er som regel en god indikator på hvor viktig et gitt habitat er. Habitatseleksjon blir derfor ofte brukt til å identifisere hvilke habitat forvaltningen bør iverksette tiltak.

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Why are animals where they are?

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Image Credit: Endre Gruner Ofstad, CC BY-SA 2.0

Guest post by Endre Grüner Ofstad. Norwegian version available here.

Use, selection, and home range properties: complex patterns of individual habitat utilization (2019) Endre Ofstad et al., Ecosphere, 10(4), https://doi.org/10.1002/ecs2.2695

The Crux

The areas in which we find an animal is often called its ‘habitat’. Yet it’s a fairly ambiguous term. Where animals are found is usually the outcome of a range of considerations, primarily foraging, predator avoidance and mating opportunities. Animals trade-off among these in order to maximise their contribution to future generations (i.e. ‘fitness’).

When considering which habitats we most likely find animals one often works with habitat selection. Habitat selection is how much a certain habitat type is used compared to its availability, i.e. what is the relative probability that an animal will use a given habitat upon encounter. The amount of time an individual spends (or density of individuals) in a habitat is usually a good proxy for the importance the habitat to the animals. Therefore we often use this to evaluate which areas to target for management and conservation efforts.

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Extreme Warming Events Could Increase Reindeer Population Stability

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Extreme warming events may sound like bad news to reindeer, but they could help increase population stability

Extreme warming events may sound like bad news to reindeer, but they could help increase population stability (Image Credit: Christopher Michel, CC BY 2.0, Image Cropped)

More frequent extreme climate events stabilize reindeer population dynamics (2019) Hansen et al., Nature Communications, https://doi.org/10.1038/s41467-019-09332-5

The Crux

Whilst climate change has been causing (and will cause) a myriad of environmental problems, it’s important to remember that not all species will be negatively affected by more extreme weather events. One example is reindeer on the Arctic island of Svalbard, according to this week’s paper.

Taken at face value, an increased frequency of extreme warming events may not sound like a good idea for a cold-adapted species. But despite the fact that it can lead to rain falling and freezing over snow, rendering massive patches of food inaccessible, the authors show that this can actually lead to increased population stability.

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