Tag Archives: use

On Moose Who Reproduce: To Use Or Not To Use

Guest post by Endre Grüner Ofstad

Opposing fitness consequences of habitat use in a harvested moose population (2019) Ofstad, Markussen at al., Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.13221

The Crux

At the heart of our understanding of animal behaviour is Optimal Foraging Theory. It’s related to the core concepts of population ecology, and essentially asks which life history trait a species is more concerned with – survival or reproduction. For instance, often for a herbivore, the areas where they will find the most food is also the area where the most predators will be lurking. This presents them with two options – eat lots, reproduce a lot, and die young, or eat less, reproduce less (at least per year) and live longer.

On a species level we can compare mice and elephants. Yet these differences also occur within species and populations. Some individuals are more prone to high-risk strategies, while others prefer the low-risk strategy. Which strategy is the best will depend on the prevailing environment. For instance, a situation with few predators (or hunters) will favour the more risk-prone strategy, while a strong presence of predators will favour the risk-averse strategy. Populations who experience environmental variations are expected to have a composition of strategies that varies accordingly. 

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Are the Combined Effects of Human Development Worse Than the Sum of Their Parts?

Decreases in river discharge can negatively affect fish like this sucker, but what happens when they’re compounded by local changes in land use? (Image Credit: Hotash, CC BY 2.0, Image Cropped)

Anthropogenic land-use change intensifies the effect of lows flows on stream fishes (2019) Walker, Girard, Alford & Walters, Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.13517

The Crux

Human activity can create a lot of different problems for the world’s ecosystems. These problems can impact an ecosystem simultaneously, often in different ways. For instance, a warming climate might push some species further towards the poles, but human structures like factories or mines might impede their dispersal. It’s relatively easy to study the effect of any one stressor that we place on a species, but looking at the interaction of multiple human-caused stressors is more difficult.

Take freshwater ecosystems. A warming climate means that there’s less snow and more rain in the winter, which reduces the river’s flow (or discharge) in summer. At the same time, nearby human construction can reduce nearby plant life, which in turn increases the amount of sediment washed into a river and lowers water quality. But do the two effects combined simply equal the sum of their parts, or does that combination make the total effect on local species even worse?

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Bob O’Hara: The Rise of the Ecological Modeller

Image Credit: Internet Archive Book Image, Public Domain, Image Cropped

Non-scientists still often think of ecologists as field workers in cargo shorts, running around a grassland with a notebook and a tape measure. Whilst I’d be remiss to say this wasn’t a percentage of us, the last two decades has seen the rise of ecological modelling, which has resulted in a new breed of ecologist. One who is capable of working almost exclusively with data, producing species distribution maps and population fluctuation graphs without leaving the office.

At the forefront of this group is Bob O’Hara, who has long claimed he plans to retire the moment he figures out whether he’s a biologist or statistician. Bob currently works at the Norwegian University of Science and Technology, spending his time with the Centre for Biodiversity Dynamics and the Departments of Mathematical Sciences. I spoke to Bob about the history of ecological modelling, its integration into the wider field, and problems with modern ecological modelling.

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Killing 2 Million Cats: When Broad Targets Aren’t Enough

Image Credit: Joey Doll, CC BY 2.0, Image Cropped

Conservation or politics? Australia’s target to kill 2 million cats (2019) Doherty et al., Conservation Letters, https://doi.org/10.1111/conl.12633

The Crux

We’ve talked a lot lately about competition between causes on Ecology for the Masses. Often when extra attention is given to one cause over another equally valid cause, it’s a product of social trends coinciding at the right time, sudden events capturing the public interest (think the Notre Dame fire) or a particularly effective marketing campaign. But sometimes a cause or a conservation target can be used to deliberately distract the public from another cause, and it’s a potential example of this that we’re looking at today.

Australia has long had an issue with cats. They’ve decimated populations of native species, playing a large hand in the extinction of many species found nowhere else. So it makes sense that part of Australia’s first Threatened Species Strategy would be to minimise the impact of cat populations on local wildlife. The strategy included a target of 2 million cats being killed between 2015 and 2020. Whilst this might sound like a reasonable goal, this paper argues that the actual scientific evidence supporting the target is pretty weak, and goes into some alternatives and motives.

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Biodiverse Gardens: Where Doing Less is More

Kiftsgate Court Garden: The Wild Garden 1. An example of a “wild garden” in the UK, where the plants have been left to grow (Image Credit: Michael Garlick, CC BY-SA 2.0, Image Cropped)

How do you make your garden more biodiversity-friendly? During my time at the  Futurum exhibition at The Big Challenge Science Festival, I spent a lot of time talking to people who expressed a desire to be manage their gardens for more plants and animals, but were unsure where to start. So I’ve compiled a brief guide on what to do, and it’s your lucky day – it involves not doing anything.

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Modernising Ecological Data Management: Reflections from the Living Norway Seminar

Ecological data is constantly being collected worldwide, but how accessible is it?

Ecological data is constantly being collected worldwide, but how accessible is it? (Image Credit: GBIF, CC BY 4.0, Image Cropped)

This week Trondheim played host to Living Norway, a Norwegian collective that aims to promote FAIR data use and management. It might sound dry from an ecological perspective, but I was told I’d see my supervisor wearing a suit jacket, an opportunity too preposterous to miss. While the latter opportunity was certainly a highlight, the seminar itself proved fascinating, and underlined just how important FAIR data is for ecology, and science in general. So why is it so important, what can we do to help, and why do I keep capitalising FAIR?

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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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