Managing puma hunting in the western United States: through a metapopulation approach

To achieve long-term viability of hunted puma (Puma concolor) populations (even at historically low densities), we propose a management plan based on the metapopulation concept that designates source areas (closed to hunting) and sink areas (open to hunting). We use 11 years of data from Idaho and Utah to demonstrate how the proposed management plan might be implemented. We use minimum and maximum densities of resident animals to calculate minimum and maximum effective population sizes, neighbourhood areas (regional management units) and usable habitat within the units. We designate sink and source areas based on their size, accessibility to hunters and juxtaposition. We show that closing 63% of puma habitat to hunting would ensure long-term puma population viability while permitting traditional hunting levels in other areas. This system could be adapted to existing state (and interstate) hunting management units, and we outline several steps by which wildlife agencies might set up a process (including public participation) to manage puma hunting. All correspondence to: John W. Laundré. Tel: 618–812–1483; Fax: 618–812–3632; E-mail: [email protected]. Animal Conservation (2003) 6, 159–170 © 2003 The Zoological Society of London DOI:10.1017/S1367943003003202 Printed in the United Kingdom 1999), or that lack of hunting provides an environment for increased puma attacks? Clarification of the overall management goals for pumas and the role of hunting in attaining those goals is badly needed. The goals of this paper are (1) to review the management of puma hunting within one study area in southeastern Idaho and northwestern Utah and (2) to suggest an alternative example of how the metapopulation concept can be used to sustain viable puma populations over the long term while allowing historic hunting levels. To accomplish these objectives, we use data from other studies and from our 16-year Idaho puma study (Laundré, 2000; Laundré & Hernández, 2000), ongoing efforts to find acceptable puma management policy in western Wyoming, and records from puma management elsewhere. Finally we offer guidelines to managers on how to implement the alternative plan proposed and reduce conflicts among interest groups. Our overall purpose is to assist in defining puma and large carnivore management policy in the public interest. Controversy over management of hunting The goal of any puma management plan should be to ensure the long-term survival of the species (Ross, Jalkotzy & Gunson, 1996). For conservation management, this goal is achieved by addressing minimum viable populations, long-term population viability, habitat protection and connectivity among subpopulations. Where puma hunting exists, this goal is embedded in strategies such as sustainable yields, target population sizes, bag limits and hunter success. Although these two approaches speak different languages, their overall management goal remains the same – long-term survival of the species. Here we adapt a management goal for pumas assuring sustainable populations for > 100 years and we then assess hunting of pumas to see if it meets this goal. Until about 1970, pumas were considered ‘varmints’ by state and federal agencies, and in all areas a bounty was paid for killing them (Hansen, 1992). In the early 1970s most states, except Texas, elevated the status of pumas to ‘game’, and established seasons and restricted take to adult males and adult females without kittens. Within these regulated seasons, there are currently three approaches to the hunting of pumas. The first we call open hunting because, within the season (usually ~6 months), there is no restriction on the number of qualifying animals that can be killed apart from the number (usually one) that an individual hunter can kill. The state is usually divided into a series of management units, and within those units all areas are open to all hunters for the length of the season. The limit on the number of pumas killed in an area is determined primarily by the number of hunters and the accessibility of the area. Second is the permit system, in which a certain number of permits are issued per management unit and allocated to hunters through a lottery. The number of permits is based in theory on some estimate of the puma population in each unit. However, there is no way to estimate puma populations accurately (Smallwood, 1997; Choate, Wolfe & Belovsky, 2000; Gratson et al. 2000), so in reality the number of permits is based on someone’s ‘best guess,’ past harvest success or – all too often – local politics. Under this system, the maximum number of animals that can be killed is equal to the number of permits issued. Third is the quota system, under which the season closes for a unit when a certain number or quota of animals, usually females, has been killed (Ross et al., 1996). Until that number of qualifying animals is killed, there is often no limit on the number of other animals, usually males, that can be killed. The basis for deciding the quota number is the same as for the permit system. Under this system, the minimum number of animals that can be killed depends on the success of the hunters or the quota of qualifying animals, and, theoretically, there is no maximum limit on the number of males that can be killed. To understand why there is controversy over these various management approaches, we need to consider each, relative to the goal of long-term survival of viable populations. In the open-hunting system, there is minimal control on the timing and length of the hunt because these seasons usually are long (~6 months) and are held in winter to maximize success. Within the hunting season, there is no limit on the take, so that given the right conditions, e.g. abundant snowfall, local puma populations can be severely over-hunted. In the past, the chances of over-harvesting were low because of the low number of puma hunters and the limited accessibility to many areas. However, the number of hunters continues to increase dramatically (Lindzey et al. 1989; Wolfe, Bates & Choate, 2000), and the use of snowmobiles and ATVs has increased accessibility significantly. For these reasons, open hunting offers little security to the long-term survival of pumas. For both the quota and the permit approaches, there is more control on the number of animals that can be killed. The permit system offers more control in that a specified maximum number of pumas can be harvested, equal to the number of permits issued. The quota system is not as precise; it specifies a maximum number of selected animals but does not limit the number of other animals that can be killed as long as the maximum of selected animals is not met. Although both approaches provide tighter control, selecting the number of permits or the quota level is still based on estimates of population numbers or, as mentioned, purely political motivations. For example, in the two state management units included in our study area in Idaho, the female quota has ranged from two to nine over the last 6 years (Idaho Fish and Game, Mountain Lion Hunting Regulations, 1994–2000). During that time, based on intensive fieldwork, our estimates of population numbers in these units ranged from 20 to 34 adults, residents and transients (Laundré & Hernández, 2000). However, there has been no relationship between population numbers and quota levels. On the contrary, the highest quotas were set in 2000 and 2001 when the population was at one of its lowest points (Laundré & Hernández, 2000), an estimated 16 resident animals of which 12 would be resident females (see calculations below). Thus, the legal quota, if filled by killing resident females, could take three quarters 160 J. LAUNDRÉ & T. W. CLARK