Puma Predation on Sheep in the Region of Torres del Paine National Park and UNESCO Biosphere Reserve, Magallanes, Chile: Conserving Top Predators and Local Livelihoods
The purpose of this project is to promote sustainable ranching amidst an environment of wildlife conservation.
Ranchers and pumas have been competing with one another in southern Chile for nearly 150 years. Adjacent to Torres del Paine National Park (TdP), on a string of ranches informally called the “Line of Fire”, the greatest incidence of sheep predation by pumas, and puma hunting by ranchers, in the Magallanes region occurs. The lack of governmental oversight with regard to this problem has engendered increasing frustration among ranchers to the point where pumas have been hunted within TdP. Yet, preliminary results from our research questions the incidence of puma predation on sheep because the majority of hunted pumas do not contain sheep remains in their stomachs. However, in contrast to these data, ranchers report a 36% loss of sheep/year due to puma predation – a total loss of nearly US$2.8 million/year.
In light of the potential emerging markets in the United States for the sale of sheep meat, and the potential negative publicity associated with long-term carnivore eradication policies, it behooves the Chilean Government and ranching sector to arrive at a sustainable solution to this escalating rancher-puma conflict. According to the USDA, the consumption of sheep meat in the U.S. approximates 170,000 tons/year. While the U.S. produces only 80,000 tons, approximately the same amount is imported from New Zealand and Australia in order to satisfy internal demand. The opportunity for Chile to enter the US market is auspicious due to: (1) inconsistent production in Australia and New Zealand because of unfavorable climatic conditions, and (2) the excellent sanitary/health conditions of Chilean sheep (e.g., no antibiotics and very few problems with disease). Since 52% of sheep in Chile are produced in the Magallanes Region, the possible entrance of Chile into the U.S. sheep market could prove to be very lucrative (Mercado de la carne Ovina. Boletin "Mercados Agropecuarios, 2007).
Within our study area (Line of Fire ranches), we are collecting ecological and economic data that will serve as the foundation of a conservation initiative. Politically, we have the interest and involvement of local stakeholders, including ranchers (local and regional), park officials (CONAF; the Chilean National Ministry of Forests and Parks), agricultural officials (SAG; Chilean Agriculture and Livestock Service), university administrators (Univ of Magallanes), and a non-profit foundation within Torres del Paine National Park (AMA Torres del Paine). Therefore, we believe that we are well-positioned for success.
To provide local stakeholders with a comprehensive action plan that will enable them to make informed decisions regarding puma management. Furthermore, we will suggest stewardship practices - - based upon puma ecology - - that will likely reduce puma predation on livestock. We envision this project as a stepping stone to a more comprehensive plan of action for puma management and improved stewardship throughout Magallanes.
A geographic analysis of 2nd generation rodenticide resistance among commensal rodents in New York
The anticoagulant rodenticide warfarin was introduced in Europe to combat rodent pests in the early 1950s. Within only a decade however, resistance to warfarin, as a first generation anticoagulant was observed in Norway Rats, Rattus norvegicus, in Scotland, and was subsequently documented across Europe, the United States, Australia, and Japan.
Because warfarin resistance reduces the efficacy of rodent pest management, more potent second-generation anticoagulant rodenticides were developed during the 1970s and 1980s. Yet resistance to these compounds was also reported soon after their introduction. This may pose potential public health risks to humans because rodent control in most cities around the world rely heavily on the use of these rodenticides, yet the commensal mice and rats harbor numerous pathogens and zoonotic diseases as well as being linked to asthma and indoor allergies.
Urbanization has likely influenced the frequency and geographic pattern of rodenticide resistance among rats and mice. The New York metropolitan area is the most populous in the US, yet resistance of mice and rats to second- generation rodenticides in New York City has not been investigated. Given the unrelenting application of second- generation rodenticides during the past 25-30 years, there is an urgent need to assess the degree and geographic distribution of second -generation rodenticide resistance should it exist among the commensal rodents of New York City. These data are crucial for the development of more efficient and cost effective control protocols, especially considering that in 2003 approximately $13,000,000 was spent on rodent pest control.
Therefore, we are collaborating with the New York City Department of Health and Mental Hygiene to conduct a DNA-based field investigation of the frequency and geographic pattern of second generation rodenticide resistance in rats and mice along an urban-rural gradient from New York City to eastern Long Island. We will collect DNA samples by trapping mice and rats from 30 locations (300 mice/150-200 rats), 3 locations in Manhattan and the outer boroughs (N=15), and 5 locations in eastern, central, and western Long Island (N=15). We will then sequence the rodent VKORC1 gene - the critical gene in which mutations confer rodenticide resistance - in order to assess the frequency and geographic distribution of rodenticide resistance. Our primary objectives are to investigate: 1) the frequency of 2nd generation rodenticide resistance, and 2) the influence of varying levels of urbanization on the geographic pattern of 2nd generation rodenticide resistance in the New York City area.
Two additional longer-term prospects are considered important for our study: (1) in-depth analyses using “next generation” DNA sequencing to potentially reveal the zoonotic potential of the commensal rodents; and, (2) the incorporation of genomic tests of selection to identify possible additional genes involved in warfarin resistance other than VKORC1. This approach should reveal loci that could then be examined for a role in the treatment response of humans to warfarin, which is also the most commonly used anticoagulant pharmaceutical (i.e., Dicoumerol) in human medicine.
Hunting of the iconic Plains bison: retaining natural mating behavior and implications for reproductive ecology
The impact of hunting (selective harvest, trophy hunting) on the demography of mammals is well documented. However, despite continual year-round hunting of bison in some populations, little is known about how the behavior of survivors may be altered. Therefore, we used focal-animal observations in adjacent populations of continually hunted and protected Plains bison (Bison bison bison) in western South Dakota, to examine the potential impact of hunting on bellowing rate - an important behavior that serves to intimidate rival bulls and potentially influences
mate choice by females. Bulls bellowed an order of magnitude more often in the protected population than in the hunted populations, whereas bellowing rate was not significantly different in the hunted populations. Hunting was significantly and negatively associated with bellowing rate, while all other predictors were found to be positively associated with bellowing rate. Furthermore, the impact of hunting on bellowing rate became more pronounced (i.e., dampened bellowing rate more strongly) as the number of attendant males increased. Changes in bellowing behavior of bulls (and possibly mate choice by cows) can alter breeding opportunities. Therefore, we have expanded the scope (geographically and scientifically) of our initial work in western South Dakota to include adjacent populations of hunted and protected bison in central South Dakota, western North Dakota, Montana, and Wyoming in order to more appropriately examine the impact of hunting on bellowing rate of bulls during the reproductive season. If reduced bellowing is associated with human hunting on a broader geographical scale, then wildlife managers may need to adjust hunting rate and duration, timing (season), and the time lag between hunting events in order to insure that bison are able to express their full repertoire of natural mating behaviors.