Originally published on Medium on 08/31/17.
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.
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 carnivores, lemurs, birds 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.
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.
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.
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.
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.
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.
In ‘Makira Lessons’, a series in the making, I’ll sum up the main findings of my published Madagascar research — and any bonus unpublishable tidbits— in a way that is accessible to everyone. If you have any questions, feel free to hit me up on twitter or contact me.
The papers that inspired this post are: