Tag Archives: population

The Culling of Kangaroos

Having recently spent some time out in country New South Wales, I thought I’d share a quick description of the sight that greets you when you get out past Deniliquin in southern New South Wales and start driving north. It’s arid land, but it’s might still be beautiful were it not for the dead kangaroos that litter roadsides. You might see fifty on the drive from Albury to Deniliquin, but that quickly turns into hundreds as you go even further inland towards the border with South Australia.

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Rethinking Extinction

Sudan, the last male northern white rhino, 3 years before he passed away, rendering the species functionally extinct. But should species like this be the focus of our conservation efforts?

Sudan, the last male northern white rhino, 3 years before he passed away, rendering the species functionally extinct. But should species like this be the focus of our conservation efforts? (Image Credit: Make it Kenya, CC0 Creative Commons)

Last year saw the death of Sudan, the last known northern white rhinoceros in the world. The story went viral, with the usual bemoaning of the way humans treat our planet, followed shortly by the normal rush back into anonymity for the world’s biodiversity. We are currently part of the most dramatic mass extinction event that the planet has ever seen, and more of these stories crop up every year. But is it a problem that the alarm bells are only raised when a creature hits the critically endangered level? Do we need to start paying more attention to population declines before hey hit such low numbers? And how do we even prioritise conservation efforts?

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Biological Annihilation

The sumatran orangutan, one of many species facing extinction in the earth's sixth mass extinction event

The sumatran orangutan, one of many species facing extinction in the earth’s sixth mass extinction event (Image Credit: Mike Pennington, CC BY SA 2.0)

Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines (2017) Ceballos et al., Proceedings of the National Academy of Sciences of the USA, DOI: https://doi.org/10.1073/pnas.1704949114

Guest Post by Jonatan Marquez

The Crux

The rate at which species and populations have been going extinct in the last couple of centuries has well and truly earned the title of the planet’s sixth mass extinction event. However, most people rarely realize the severity of the situation. Hearing about the loss of two vertebrate species a year or having the last of some far-off species die out doesn’t see to cause much concern in the general public.

A species extinction is always preceded by population declines and extinctions. Perhaps highlighting the state of natural communities at this level might put the severity of the situation in better context. For example, the Living Planet Index (LPI) estimates that between 1970 and 2012, wildlife abundance has decreased by 58%. This paper focuses on the state and trends of populations of vertebrates by analysing i) the proportion undergoing declines or shrinkages, ii) the global distribution of population reduction events and iii) the general scale of population declines among mammal populations.

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The American Mink

The American Mink is pretty much a Norwegian mainstay these days. So what sort of impact have they had?

The American Mink is pretty much a Norwegian mainstay these days. So what sort of impact have they had? (Image Credit: Ryzhkov Sergey, CC BY-SA 4.0)

Fur farming isn’t a topic we’ve had much cause to touch on so far in this series. But today, we look at a species that was introduced specifically for that purpose, whose presence in Europe is disliked by ecologists and animal rights activists alike.

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Population Trends in the Face of Climate Change

The Indian Pond Heron, one species which could face population declines as a result of climate change

The Indian Pond Heron, one species which could face population declines as a result of climate change (Image Credit: Dr Raju Kasambe CC BY-SA 4.0)

Rapid warming is associated with population decline among terrestrial birds and mammals globally (2018) Spooner et al., Global Change Biology, DOI: 10.1111/gcb.14361

The Crux

The term climate change is almost ubiquitous these days. Humans tend to concentrate on how the warming of certain parts of the globe will affect them, but the species we share the globe with also experience a myriad of effects at the hands of climate change. These include rising temperatures constricting the ranges of some species and concurrently extending the range of others, who can move into areas that were previously too cold for them.

Whilst the focus of climate change has often been on species range shifts, the effects on species abundances are less well studied. This paper attempts to quantify the effects of climate change on a large number of bird and mammal species, whilst accounting for other factors which could affect species abundances, like rates of land use by humans, species body size, and whether or not the animals are in a protected area.

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Costa Rica: Sustainability in an Animal Paradise

Costa Rica has taken huge steps forward in the last 30 years to save their ecosystem, with the tourism industry benefiting enormously

I’ve just returned from a two-week vacation in Cosa Rica. While ostensibly a holiday, if you’re an ecologist in a country where ecological conservation forms the basis of their tourism industry, it can be hard to switch off. So amongst a plethora of monkeys, iguanas, basilisks, hummingbirds and crocodiles, I noted a few things which are worth briefly discussing before we get back into our regular blogs next week.

A warning though. Whilst a fair bit of well-researched content appears on this website, the observations here are much more general, and by no means applicable to the whole country.

  1. The Plastic Addiction

I know this isn’t exactly a hot take. Plastic consumption is one of the world’s foremost environmental catastrophes, and if the enormous soup of plastic in the middle of the Pacific wasn’t enough to ram the point home, the four others forming around the world should be.

What surprised me here was that despite the emphasis the Costa Rican government places on the conservation of biodiversity, there appears to be no effort in the tourism industry to shy away from easily avoidable plastic use. Plastic straws and cups were in abundance, but the real mind-boggler was the use of small plastic bags to contain cutlery. Having knives and forks handed to me in new plastic casing at half the restaurants we visited was an odd experience, and one which seems easily avoidable.

However we encountered a few places which eschewed the plastic wrapping and provided cardboard straws. Hopefully this is a growing trend.

  1. Animal Sanctuaries

One thing Costa Rica was far from short on was recovery centers for injured animals. We visited one in Cahuita, and were impressed by the number of volunteers they had managed to attract, most seemingly without any background in zoology. Other centers had one-day volunteer programs advertised, which were often tailored to getting children involved. The centers require government permission to release any individuals back into the wild, which seems to be an effective communication pathway. Yet like all dialogues between organisations with different priorities, it produces disagreements. We heard many examples of rehabilitated animals that the government considers too used to human exposure to reintroduce.

The center we visited did seem to focus more on animal welfare than population conservation (though they certainly did not ignore the latter), and associates who have previously volunteered at these centers seem to agree. There were several examples of animals who, even with rehabilitation, were incapable of contributing to population viability, or whose injuries were not directly or indirectly caused by humans, some whose removal from the population could be considered important contributors to genetic and behavioural evolution. However staff made the excellent point that with the number of these species that receive injuries from human activity every year, the least they could do is try to treat a few injuries that weren’t.

Whilst iguanas used to be a food source for the locals, local hunting is now restricted

Whilst iguanas used to be a food source for the locals, local hunting is now restricted (Image Credit: Sam Perrin, NTNU)

  1. Conservation Laws

Costa Rica’s conservation laws prohibit the killing of many species found throughout the country. No complaints here. Many of these species are integral parts of the Costa Rican ecosystem and tourism industry. However a guide from the Caribbean side of the country was discussing his family’s traditions of hunting many of these animals, and how the government provided no alternatives to these traditional food sources when the laws were introduced. Whilst I am all for criminalising the killing of endangered species, having a government tell your family to change their lifestyle, whilst they continue practices that have a much larger impact on the native ecosystem (ongoing deforestation and commercial harvesting amongst them) must rankle somewhat.

Having said this, I live in a country where hunting quotas are strict and easy to monitor, and contact between hunters and the government is frequent. Commercial harvesting is potentially an easier way to manage sustainable population of harvested species, and a source of employment for families in need of new income.

 

In conclusion, I’ll reiterate that much of the above may be a product of observational bias. Bias also leads me to suggest that regardless of your thoughts on the above, you go and check out Costa Rica for yourself. It’s marvellous.

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