Conservation trade-offs: Island introduction of a threatened predator suppresses invasive mesopredators but eliminates a seabird colony (2020) Scoleri et al., Biological Conservation, https://doi.org/10.1016/j.biocon.2020.108635
Invasive species are a nightmare for local wildlife wherever they are, but on islands they’re even worse. Introduced predators can wipe out entire populations of species, as Tibbles the cat and his fellow feral buddies demonstrated in the extreme when they drove the Lyall’s wren extinct. On coastal islands this is a recurring theme. An invasive ‘mesopredator’ – like the American Mink in Europe or the cat in Australia – is introduced and quickly goes to work, often on small mammals, birds, reptiles and amphibians alike.
Sometimes, but not always, introducing a top predator to an area can suppress the activities of the mesopredator. They can outcompete the mesopredator for resources, or begin to prey on them. The problem is, that if that top predator goes after the same food as the mesopredator, the local prey species suffer either way.
Image Credit: Dmitry Teslya, CC BY 2.0, Image Cropped
Species-area relationships on small islands differ among plant growth forms (2020) Schrader et al., Global Ecology and Biogeography, https://doi.org/10.1111/geb.13056
We’ve talked a lot about Island Biogeography Theory (IBT) in the last couple of weeks. One of the key tenets, established way back in the 60s, is that as an island’s area decreases, its species richness tends to as well. Yet since IBT was conceptualised, there have been a number of amendments made to it. The Small Island Effect (SIE) is one of them.
SIE essentially means that below a certain threshold (called a ‘breakpoint’), species stop obeying that species richness to area relationship. This week’s researchers wanted to test whether that breakpoint was different between species groups, and whether the species area relationship changed below that breakpoint, or simply disappeared.
I sat down with leader of the UK Ladybirds Survey Helen Roy to talk about the stigma surrounding invasive species like this Harlequin Ladybird (Image Credit: PJ Taylor, Pixabay Licence, Image Cropped)
While climate change and habitat loss seem to keep making all the headlines when it comes to environmental damage, invasive species are still chugging along comfortably as the second biggest threat to our planet’s biodiversity. New cases are popping up all the time, with the Burmese python, Crucian carp and the emerald ash borer beetle recently reaching new levels of notoriety.
Yet the negative impact that many non-native species have on the habitats they move into have often led to stigmatisation of anything new. This can be counter-productive, as the majority of newcomers into an ecosystem won’t have a pronounced negative effect. And whilst it may seem like a smart piece of preventative management to maintain an ecosystem’s status quo by preventing species introductions, it’s often just not feasible.
With this in mind, I sat down at the recent British Ecological Society’s Annual Meeting with Professor Helen Roy of the UK Centre for Ecology and Hydrology. Helen has studied the impacts of non-native species the world over, from the UK to smaller island nations like St. Helena, and has led several projects for the European Commission on non-native species. We spoke about the importance of distinguishing between invasives and non-natives, the impact of climate change on invasive biology, and the social and cultural significance of both native and non-native species.
Mandt’s Black Guillemont (Image Credit: Óskar Elías Sigurðsson, CC-BY 2.0, Image Cropped)
Phenotypic plasticity or evolutionary change? An examination of the phenological response of an arctic seabird to climate change (2019) Sauve et al., Functional Ecology, https://doi.org/10.1111/1365-2435.13406
If you’re here on Ecology for the Masses, then you know that climate change is not only real but is causing all kinds of problems for organisms the world over. One of the things that climate change is doing is altering seasonality, the time of year in which a given season will take place. For example, where I live in the US, it is normally cold at this time of year, but as I write this it is 60F/16C, much warmer than it should be despite it almost being winter. These changes can affect when organisms start their seasonal breeding, but how these breeding events change is not always the same.
Some changes are due to evolution, or the change in a population’s gene frequencies over time. As mutations and selection take place, a given population may have some traits or behaviors selected for over others. Another way that these changes can happen is via plasticity, which is a change induced by the environment, but without changing the gene frequencies (See Did You Know? for more information). The authors of today’s paper wanted to know if the change in breeding dates of a colony of seabirds (Mandt’s black guillemont, Cepphus grylle mandtii) was due to evolution or plasticity.
Image Credit: The Little Mermaid, 1989
Adam regales us with one of the weirdest stories I’ve ever heard, and in case you were wondering, yes we do talk about how mermaids have sex. Jesus. Also there’s some cool ecology. Like how did mermaids evolve? Was it from a mutated baby tossed overboard? Probably not.
05:19 – Mermaids in Cinema
16:35 – Ecology of the Mermaids
33:25 – Mermaid Copulation (you were warned)
38:07 – The Mermaids vs. Jaws
You can also find us on iTunes and Google Play.
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, Image Cropped)
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?