The Times Are A Changin’: Declines in Native Wildlife in Madagascar

Originally published on Medium on 08/31/17.

A ring-tailed vontsira, a small native carnivore that is facing declines at two sites in Madagascar.

A ring-tailed vontsira, a small native carnivore that is facing declines at two sites in Madagascar.

It is the early 21st century. Cheetos are hot, avocados are putting millennials into debt, and where traveling across the ocean used to be a months-long endeavor on a ship filled with danger, disease, and a dearth of food variety, now one can simply deal with the above on a plane for less than a day.

Things are also changing in tropical countries like Madagascar, despite the idea of these places staying forever a nature lover’s wonderland. Teenagers dance to a mixture of French-Malagasy pop blasted on cellphones, motorized lakanas run on consistent schedules up and down rivers, and even the most remote forest area is vulnerable to invasion by non-native species like dogs and cats.

A kitty where it should not be (a remote Malagasy rainforest).

A kitty where it should not be (a remote Malagasy rainforest).

As human pressures on ecosystems continue to increase, animal populations can start to decline and the world could get a little less wild. Long-term monitoring of sites can help scientists catch these declines before they get too far along to be stopped. Zach Farris and I were able to do this for native carnivoreslemursbirds and small mammals in northeastern Madagascar. And thanks to the publicly available TEAM Network dataset, Zach was also able to look at how carnivores populations were faring in Ranomafana National Park.

Declines in native carnivore, bird, and small mammal occupancy (gray) over six years at a site in northeastern Madagascar. Meanwhile, feral cats (black) became more common at the very same site.

Declines in native carnivore, bird, and small mammal occupancy (gray) over six years at a site in northeastern Madagascar. Meanwhile, feral cats (black) became more common at the very same site.

At our northeastern site, we saw declines in 8 out of 15 native carnivore, small mammal, and bird species monitored. The two carnivores with the largest decline in occupancy were the brown-tailed and broad-striped vontsiras, two small native carnivores that are already uncommon in the northeast.

Brown-tailed vontsiras (left) and broad-striped vontsiras (right) are both listed as Vulnerable and declining by the IUCN.

Brown-tailed vontsiras (left) and broad-striped vontsiras (right) are both listed as Vulnerable and declining by the IUCN.

Their declines might be connected to simultaneous declines in birds and small mammals; it might also be connected to further logging on the site and/or the presence of non-natives. Feral cats and small Indian civets, which weren’t seen the first year of our surveys, appeared to become more common at the site as the years went on, and both species are large enough to kill the smaller vontsiras.

In Ranomafana, similar changes appeared to affect two of the five native carnivores found in the park.

Fosa (the largest native carnivore) and ring-tailed vontsiras declined in Ranomafana while human use of the park increased.

Fosa (the largest native carnivore) and ring-tailed vontsiras declined in Ranomafana while human use of the park increased.

While fosa at our northeastern site did not show any declines, fosa in southeastern Ranomafana did. Ring-tailed vontsiras, which showed a decline in the northeast, also seemed to become more uncommon in Ranomafana as the years went on.

A fosa (left) and a ring-tailed vontsira (right). Ring-tailed vontsiras aren’t of conservation concern YET, though population declines are cause for concern.

A fosa (left) and a ring-tailed vontsira (right). Ring-tailed vontsiras aren’t of conservation concern YET, though population declines are cause for concern.

So what does this mean?

Although both sites are protected, we’re still seeing declines in native wildlife populations. Unfortunately, we aren’t able to determine the direct causes just by using trail cameras, but evidence from across the world points to three possible culprits: logging, hunting, and interactions with non-natives.

Zach found that the more dogs there are in the forest, the more uncommon and more nocturnal fosa tend to get. In addition, ring-tailed vontsiras are very popular as bushmeat in the northeast; it is possible that they have the same popular status in the southeast. Finally, obviously the loss of their home/grocery store/night club/nursery (i.e., the forest) could be bad for wildlife. While we do not have direct data on this, simply looking at the sites on Google Earth can show that there have been changes in forest coverage over the years.

Differences in forest cover between 2008 and 2016 at our northeastern site.

Differences in forest cover between 2008 and 2016 at our northeastern site.

But while educated, these are all guesses. We would need to look at a variety of things at both sites to determine the true causes of the declines: whether native wildlife is dying and/or moving from the site, what native wildlife is eating and whether what they’re eating is also declining, whether dogs and cats are actually killing native wildlife, and how many animals are being killed each year for bushmeat. All of this requires more than a trail camera set on a tree. All of this also requires a lot of money that seems to be as rare as a brown-tailed vontsira in a dog park (i.e., nonexistent).

As of right now, we would like to continue trail camera monitoring at both sites, but we have no funding. What will we see in the years to come? Will native wildlife populations bounce back, or will they continue to decline? Only the future knows.