Tag Archives: habitat

Hvorfor er dyr hvor de er?

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?

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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Frivillig vern sin rolle i naturvern

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

Guest post by Endre Grüner Ofstad.

Privately protected areas provide key opportunities for the regional persistence of large‐ and medium‐sized mammals (2018) Clements et al., Journal of Applied Ecology, 56(3), https://doi.org/10.1111/1365-2664.13300

Det Essensielle

Da mennesker slo seg ned i nye områder, bosatte de seg som regel i de mest produktive og artsrike områdene. I dag, mange år senere, er disse områdene fortsatt produktive og i private hender. I dag, derimot, blir flere og flere arter utrydningstruet og vi iverksetter tiltak for å redusere tapet av arter. Et av disse tiltakene er verneområder. Verneområder er områder som er satt til side for å sikre tilstedeværelse av gitte arter eller naturtyper ved å begrense høsting eller annen menneskelig innflytelse. Utfordringen er at dette ofte er kostbart da disse artsrike områdene ofte overlapper med områder som har viktige jordbruk- eller andre naturressursinteresser. Dette resulterer i at vernede områder ofte blir lagt til økonomisk marginale og/eller statseide områder. For å kontre dette kan en inkludere områder tilbudt frivillig av grunneiere. Spørsmålet blir da, hva er verneverdien av de områdene som blir tilbudt? Dette er spørsmålet som Clements og medforfatterne spør seg når jobber med Cape Floraregion i Sør-Afrika .

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The Role of Private Property in Conservation

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

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

Privately protected areas provide key opportunities for the regional persistence of large‐ and medium‐sized mammals (2018) Clements et al., Journal of Applied Ecology, 56(3), https://doi.org/10.1111/1365-2664.13300

The Crux

When humans settle down in new areas, they usually settled in the most productive and species-rich areas. Now, years later, these productive areas are usually still productive, but often still in private hands. However, today more and more species are facing extinction, and many would be helped by the protection of these areas. Protected areas are areas that are set aside to ensure the viability of certain species by limiting human exploitation of the local natural resources. However, this might be costly, and these hot-spot areas likely overlap with agricultural or other natural resource exploitations, with the result that protected areas are often located to economical marginal and state-owned lands. To counter this, one might include lands offered voluntarily by private owners. But are the lands they’re offering of any conservation value?

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Ecology in Media: Thoughts, Questions and the Insect Apocalypse

Recent reports of collapses in insect populations were eagerly devoured online. But were the reports exaggerations, and if so, how did they make it into the headlines? (Image Credit: Barta IV, CC BY 2.0)

Two weeks ago, an article on the Insect Apocalypse hit my Facebook feed. It popped up everywhere. People seemed genuinely concerned about the plight of the world’s insects, which was a first for me.

An hour later I was sitting at a conference seminar in which the speaker bemoaned the poor data that had contributed to the key statistic in the article: that biomass of flying insects had decreased by 75% over the last 27 years. The methods used in the report apparently show huge bias towards large bodied species, which may have exaggerated the findings significantly. So here lies our quandary. Read more

Mapping Species Distribution with Citizen Science

 Community, or citizen, science is a huge, often untapped data source for ecologists. So what are the pitfalls of using it? (Image Credit: Jacob W. Frank, CC BY 2.0)

Occupancy models for citizen-science data (2018) Altwegg & Nichols, Advances in Modelling Demographic Processes, 10, p. 8-21

The Crux

Species distributions maps are great. I remember rifling through animal encyclopedias as a kid, checking out the distributions of my favourite animals, just assuming that people knew exactly where to find all these organisms. But the reality is that figuring out exactly where species live is extremely difficult.

It’s made easier, however, by the use of citizen (or community) science. This occurs when volunteers involve themselves in projects in which they observe and report the presence or absence of a species in a given area, which is then used to determine a species’ distribution. This data is obviously incredibly useful to any ecologist, but it comes with some drawbacks. This paper attempts to summarise those drawbacks and outline ways to work around them.

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