Predators are known to affect prey while they are adults and juveniles, but what about when they haven’t even hatched yet? (Image Credit: Bernt Rostad, CC BY 2.0)
Predation risk affects egg mortality and carry over effects in the larval stages in damselflies (2018) Sniegula et al., Freshwater Biology, p. 1-9
In the natural world, one of the most dangerous things that a prey animal has to worry about is a predator. These organisms depend on the prey for their sustenance, and as such have become very good at finding ways to eat them. These are known as direct effects, as a predator eating prey is a direct interaction.
Another aspect of the predator-prey relationship is that of indirect effects, or effects that a predator has on prey that don’t involve it eating the prey animal. These can include predator-induced changes in the prey’s behavior, immune function, or even survival. These indirect effects are usually studied in prey species that are adults or juveniles, but the authors of today’s paper were interested in what indirect effects predators had on the eggs of prey species.
In our second week on the dragons of Dreamworks’ How to Train Your Dragon trilogy, we have a flamin’ good time discovering why those dragons are WAY too wacky, exactly how much intraspecies predation goes on in Berk and why you should really make up your mind about domestication.
03:49 – Vikings in Cinema
10:57 – Ecology of the Dragons
29:17 – Toothless vs. the Furious Five
You can also find us on iTunes and Google Play.
A release of the formerly endangered Running River Rainbowfish. So how were they brought back from near-extinction? (Image Credit: Karl Moy, University of Canberra, CC BY-SA 4.0)
We talk a lot about getting the public interested in conservation and ecosystems on Ecology for the Masses, but we’ve rarely talked about how conserving a species is actually accomplished. Where does funding come from? How do you decide which individuals to save? And how do you allow a population room to grow?
In 2015, Peter Unmack was sampling in the Burdekin river system in northern Queensland, Australia, when he noticed an alien population of Eastern Rainbowfish had established in Running River. Specifically a 13km stretch bounded by two gorges, which housed the Running River Rainbowfish, a species distinct to this one stretch. Knowing that the presence of the Eastern Rainbowfish could spell the extinction of the local species, he started a crowdfunding initiative, and essentially saved the Running River Rainbowfish. I spoke to Peter and postgraduate student Karl Moy about the conservation effort.
The Raccoon Dog, an alien species, has made its way to Sweden recently. But what sort of effect does it have on the native fauna? (Image Credit: Prue Simmons, CC BY 2.0)
Nest predation by raccoon dog Nyctereutes procyonoides in the archipelago of Northern Sweden (2018) Dahl & Åhlen, Biological Invasions, https://doi.org/10.1007/s10530-018-1855-4
We’ve spoken about biological invasions at length on EcolMass, and the detrimental effects that the arrival of a new species can have on native populations. Yet eradication is often impossible, and management expensive, so before taking extensive action, it’s always important to ensure that an alien species IS having a negative effect.
The raccoon dog is an Asian species, closely related to foxes, that was introduced to Europe in the early 20th century and has since spread into Scandinavia. Voracious predators that could spread further north due to climate change, our paper this week looks at the extent of their impact on the ecosystems they’ve spread to.
Feral cats are responsible for the decline of many endemic species worldwide. But will removing them boost rat populations, causing more potential harm? (Image Credit: Brisbane City Council, CC BY 2.0)
Trophic roles of black rats and seabird impacts on tropical islands: Mesopredator release or hyperpredation? (2015) Ringler et al., Biological Conservation, https://doi.org/10.1016/j.biocon.2014.12.014
For centuries, rats have been portrayed as carriers of diseases and death; whereas our feline friends, worshipped by the ancient Egyptians, will definitely make your YouTube video go viral (a quick Google search of “cat video” shows 1 310 000 000 results). Both have been introduced, either accidentally or deliberately, to islands where endemic species have evolved and adapted to an environment without these generalist predators. So how do you know if eradicating one of them will make things better for the native wildlife?
Before taking radical conservation actions, it may be a good idea to understand how feral cats (the apex predator), rats (the mesopredator) and their common prey are affecting each other. Namely, if you kill all the cats, will there be more rats to prey on seabirds? On the other hand, will killing all the rats really reduce the predation by cats on seabirds?
Reef accessibility impairs the protection of sharks (2018) Juhel et al., Journal of Applied Ecology 55
Species such as this Carribean reef shark have higher extinction risks than most fish. But how effective are our management efforts? (Image Credit: Wikipedia Commons)
The importance of sharks goes well beyond what Jaws did to Hollywood, or one week in the USA each July. In any reef ecosystem, sharks perform a key functional role, exerting top-down pressure, stabilising food webs, and improving general ecosystem functioning. They’re also ‘charismatic’ species, meaning they’re easier to raise funding for, and bring money in through tourism. Yet pressure from fishing suggests that reef shark populations may be under threat, and with high body sizes and long lifespans, their populations are more sensitive than most to overfishing, making extinction risks higher.
Yet the lack of data on shark populations means that the effectiveness of the few existing management programs is largely untested. This paper looks at Marine Protected Areas (MPAs), areas in which national or international bodies prevent fishing or even entry, to see whether or not they are an effective conservation method for shark populations.
Fear and lethality in snowshoe hares: the deadly effects of non-consumptive predation risk (2018) MacLeod et al., Oikos 127(3)
Fear itself of a predator is enough to reduce populations of a snowshoe hare, show Macleod at al. (Image Credit: Dave Doe, CC BY 2.0)
When we think of a predator-prey relationship, many colorful examples of charismatic animals come to mind: the lion and the wildebeest, the orca and the seal, the owl and the mouse. We think of these organisms locked in an endless battle, with one needing to catch and eat, the other to escape and live. While these are definitely interesting and important aspects of the predator-prey relationship, prey species need to worry about more than just being eaten. These “non-consumptive effects” play into what is called the Ecology of Fear.
This study was an attempt to show that the perceived risk of predation itself was enough to reduce survival in prey species. Unlike previous studies on this question, MacLeod et al. were the first to conclusively show this effect in mammals.