Wednesday, April 18, 2012

Redirecting Wildlife Services

The American Society of Mammologists put out a letter to congress calling for that body to redirect the efforts of Wildlife Services, "...specifically to substantially reduce its funding for lethal control of native wildlife species, especially native wild mammals." I should say up front that I think their requested change in Wildlife Services actions seems to me quite reasonable. I think where they are most off the rails is claiming that science doesn't support the use of lethal control ... again, it has nothing to do with science! The best arguments are political ones pointing out the expense and lack of documented effectiveness of predator control.  

That the society is interested in political gains through science is clear from this quote regarding the society's very first resolution:
The Society’s first resolution (1927) called for science, not politics, to inform government policy on predator control.
Connections between coyote control and rabbit outbreaks are speculation at best.

I followed up a couple of the references, e.g. Alcock 1990 (in the LA Times, a highly respected scientific outlet), who cites his colleague Gerald Cole as having "written a paper on this". The paper in question turns out to be a piece in the "Defenders of Wildlife" newsletter from 1970! Hardly a peer reviewed source! 

Now, their arguments may in fact be correct, but there certainly is no peer reviewed evidence supporting their assertions. If there was, they should be citing it! On the face of it, scientific or not, killing ~560 river otters per year while simultaneously trying to reintroduce them seems counterproductive, but if the animals are abundant in places where they are being accidentally trapped, then there isn't really an issue. In fact having them turn up in beaver traps may be an indication of stunning success!

The idea of mesopredator release is relatively well supported in the literature, although not specifically with coyotes and wolves. However, the society should pay close attention to the articles it cites, e.g. Prugh et al (2009) cited in support of mesopredator release, also say: 

" ... predator management is characterized by complex ecological, economic, and social trade-offs. While large predators present many ecological benefits, they can also pose a serious threat to species of conservation concern. For instance, cougars (Puma concolor) contributed to the near extinction of endangered Sierra bighorn sheep in the 1990s (Ovis canadensis sierrae; Wehausen 1996). Any proposal to protect or reintroduce apex predators must acknowledge the full range of trade-offs involved in predator management."
The key phrase is that there is a range of tradeoffs involved in predator management - what they don't say is that those tradeoffs are highly political, not scientific. The society's letter also cite Estes et al 2011 - a paper in Science - as support for apex predator effects. Again, no denying that trophic cascades have occurred, but also no strong evidence for the particular effects cited in the letter. In fact Estes et al say 

"We propose that many ecological surprises that have confronted society over past centuries—pandemics, population collapses of species we value and eruptions of those we do not, major shifts in ecosystem states, and losses of diverse ecosystem services—were caused or facilitated by altered top-down forcing regimes associated with the loss of native apex consumers or the introduction of exotics." 

The key word is PROPOSE. This is a plausible hypothesis, but far from a proven theory.

Stealth issue advocacy. Devalues the science and misdirects the political debate.


  1. Thanks to Tim for bringing the letter to my attention and pointing out the whacky formatting that arose from copying an email out of gmail and pasting into blogger.

  2. Comment from someone who wished to remain anonymous:

    "The majority of this killing is complaint-driven, not science-driven." Probably quite true.

    "More recently, there has been evidence that WS sees another role for itself, and that is to increase the population density of certain favored game species such as elk, ostensibly by targeting entire wolf packs for extermination by aerial gunning..." What ASM doesn't seem to understand or perhaps acknowledge is that, in my opinion, WS does not make wildlife management decisions. They are not what I would call a wildlife management agency – an agency that sets wildlife management objectives, implements actions to meet those objectives, and then hopefully monitors their actions. WS seems to fall into the middle of this – implementation.

    This may vary by state, but WS is funded by federal, state, and county sources, including state wildlife agencies, state ag depts., and county commissions. It’s irrelevant whether WS needs a state or federal permit to implement any actions. They do what they are directed to do and funded to do, nothing more. If a state or federal permit is needed (or a formal IGA), which is probably the norm for "big game," then the decision was made by that state or federal agency to implement or allow a management action by WS; it was not a decision by WS. If a federal or state agency tells WS to kill wolves in a location at a certain time, then that’s what they do, and they do it as quickly and efficiently as possible. With such a huge social acceptance component to management of wolves, there are and certainly have been instances where lethal action may aid in long-term population recovery (although perhaps at a slower rate). Admittedly, this probably seems counter-intuitive. If a landowner (a rancher that helps fund WS at the county level) tells WS to kill species x, y, and z on his or her ranch, WS does just that, if legal. WS seems to be filling a socially driven niche in wildlife management, so to speak. It will be very interesting to see if and how WS evolves over the next few years. I am not championing predator control or WS, just sharing observations here.