In my last post, I provided a glimpse of fisher history and ecology, talking about changes within the Northeast population, fisher diversity along the Pacific coast, and their impact on prey populations. This week I pondered the fisher-human relationship and how they react to the ways in which we’ve changed the environment around us and them. Luckily for me (and anyone who is interested), there are several researchers who have worked hard to give us a peek into the life of the suburban/urban fisher, and some of the data they’ve collected is simply amazing. To a certain extent, it also gave me a small slap to the forehead for accepting without question what people around me had been saying about fishers.
Dr. Roland Kays is a fascinating guy (when I spent a few hours with him at the New York State Museum in 2010, I got a crash course in kinkajou ecology, current motion-sensor GPS gadgets, and the debate over oil and gas extraction in New York- it was a busy morning…) who has done a lot of work with a wide variety of animals, including fishers. Now at the North Carolina Museum of Natural Sciences, while at the New York State Museum in Albany, he and Scott Lapoint started tracking fishers between Schenectady, Troy, and Albany and then discussing some of that work in the on-line New York Times’ “Scientist at Work” blog (this is a very neat site that I highly recommend- a variety of scientists make regular posts about their field work- it’s a great way to get a sense of work that’s being done and how researchers approach their studies). One of their goals was to understand how fishers have adapted (or not) to an urban environment- as it turns out, fishers know how to take advantage of opportunities. And they also may be taking the blame for someone else. (What I provide below is a summary of several of his posts.)
A carnivore drive-through? It sounds a little far-fetched (and this is my analogy, not the researchers), but fishers may actually have access to something similar. The animals Kays and Lapoint tracked were covering a good amount of ground as they moved from forested area to forested area, and that required crossing some very busy roads (and we’ve all seen what happens to crossers who take too long…). When one animal kept crossing the same road at the same point, they decided to do a little groundwork and found a culvert in that location- the fisher was avoiding traffic by going under the road. A little more legwork at locations around the study area and a definite pattern had emerged of fishers using culverts to avoid cars. There were even signs that fishers had used the culverts for other purposes: a rest-stop and a hunting ground (other animals, including hares and other fisher-prey, were using the culverts to cross roads as well- if you happened to time it correctly, your favorite meal might come walking toward you- granted, you’d still have to catch it, so it isn’t quite like placing an order, but it certainly would help to have your prey funneled toward you). Why is this important? One of the big issues of city-living for many animals is that forested areas are quite small and spread out, so finding enough good habitat is a challenge and getting between those sites involves a lot of risk. As carnivores who already need a large territory, fishers have to move around a lot in urban conditions to find adequate food- if they can use culverts as safer ways to get from forest patch to forest patch, they can more easily survive in urban areas (which is an interesting situation for an animal often described as needing wilderness). It’s also helpful during the reproductive period when they have to travel to find other fishers. If you check out previous posts from Dr. Kays’ blog, there are some wonderful maps showing how fishers have been moving around Albany and other areas- the one of the golf course, in particular, is a great example of an animal using forest fragments.
And what about those cats? Dr. Kays investigated fisher diets through two studies: a) with an undergraduate student he collected 24 scat and stomach samples for analysis, and b) with Lapoint he visited 25 kill sites from tracked fishers. In both cases, they found that fishers use many different food sources, but none of those sources was a cat. (Gray squirrels, on the other hand, constituted about 20% of the diet of suburban fishers.) He did mention one study in Massachusetts that listed two observations of a fisher eating a cat, but he remains skeptical of the likelihood that most missing cats were victims of a fisher. (And I found it very interesting that he mentioned he heard the “fisher got your cat” theory particularly from people in New Hampshire– what is that all about?!) So what did get the cats? It’s hard to give a blanket statement on that since the main issue with a lost cat is that you don’t ever see it again, but there is another possible culprit out there, aside from traffic and raptors (which almost got our cat one year, as evidenced by the talon-marks raked across his back and his tendency to bolt for cover every time a shadow passed over him). Coyotes are known to kill cats (Crooks & Soule 1999) and they are widely-distributed across North America; Kays feels they are a more likely reason for those missing cats than fishers.
Having done a little digging in terms of fisher ecology, I think they are pretty amazing animals. I’m quite impressed with how they have made urban environments work for them, an important skill given how cities and suburban areas continue to grow. There are bound to be areas of conflict when humans and carnivores share the same areas, but I think that a lot of that conflict comes from fear and misunderstanding of the ecology and behavior of animal. Fishers are tough and daring (would you hunt alongside I-87?), and they do play a role in regulating small animal populations (just imagine more gray squirrels out there…)- what role can we play in their future? That’s the topic I’ll tackle in my next post.
Crooks, K.R. and M.E. Soule. 1999. Mesopredator release and avifaunal extinctions in a fragmented system. Nature 400: 536-566.
Kays, R. “Albany’s Urban Weasels” The New York Times Scientist at Work Blog on-line January 25, 2011.
Kays, R. “Do Fishers Really Eat Cats?” The New York Times Scientist at Work Blog on-line April 6, 2011.
Kays, R. “Tracking Urban Fishers Through Forest and Culvert” The New York Times Scientist at Work Blog on-line February 9, 2011.
Kays, R. “When a Fisher Goes Missing” The New York Times Scientist at Work Blog on-line March 3, 2011.