WASHINGTON (ISNS) -- Changes in the popularity of sport hunting might contribute toward an increased possibility of population collapse for hunted game if regulations are too slow in adjusting seasonal hunting limits, according to a new study by a team of ecologists.
Regulations, limits, and quotas are part of the fabric of modern hunting. Minnesota issued hunters only 225 permits to hunt moose last year. Mississippi closed a lottery last week for hunters vying for one of 260 permits to bag two full-grown alligators. And according to the Alaska Department of Fish and Game, this year some 15,000 hunters will apply for about 100 permits to hunt one of the 900 or so buffalo belonging to four of the state's free-roaming herds.
Limits like these are designed to sustain wild game populations and avoid situations like what happened to the deer in New Hampshire a few decades ago. Beginning in the late 1960s, their numbers decreased dramatically for more than a decade because of several severe winters, and according to Kent Gustafson, a wildlife biologist who manages deer for the state of New Hampshire, the populations did not start to rebound until the early '80s, when tighter regulations came into effect.
"Since then we have gotten populations back up to historic levels," said Gustafson.
Now a new study by ecologists in the U.S., Canada and Norway suggests another factor that can lead to population collapses like the one suffered by the New Hampshire deer. According to ecologist John Fryxell of the University of Guelph in Ontario, Canada, there is an important underappreciated human factor involved as well: swings in the popularity of hunting.
In an article published in the latest edition of the journal Science, Fryxell and his colleagues show that changes in the behavior of hunters may place game populations at a greater risk of collapse if hunting regulations are too slow or too incremental in adjusting to the changes in the size of the animal populations.
Across the United States, wildlife managers who work for a hodgepodge of state and federal agencies set limits restricting areas where hunting is permitted, capping the number of kills, regulating the size, sex, and age of animals that can be hunted and restricting hunts to certain hours of the day and times of the year. These limits are put in place, said Fryxell, to respond to changes in animal populations from year-to-year. If the population of a game animal drops, wildlife managers may restrict hunting, and if a population booms, they may increase quotas or open up new ranges for hunting.
In the early 1980s, wildlife managers in New Hampshire made dramatic changes to their rules on deer hunting as a way of rebuilding the population. They began to limit the number of female deer that could be killed during the hunting season According to Gustafson, they also began "micro" managing deer numbers, not on a statewide level, but in smaller 500 square mile areas.
Though Fryxell and his colleagues did not explicitly look at New Hampshire's population of deer, their new study may reveal some of the dynamics that were at play during the decline. They modeled and predicted the effect of wildlife management strategies and the influence of human social factors on number oscillations of everything from fish to elk to bobcat to moose over long periods of time -- decades.
Fryxell said that the impact of the social factors they considered had never been fully appreciated, but it appeared to be the major factor causing dramatic swings in game populations -- variations that may actually place those populations at greater risk of collapse.
"We have a lot more variation than needs to be there," Fryxell said.
The swings occur because as hunters enjoy successes or failures in their endeavors, they share information with people in their social network. A successful hunter may perpetuate the popularity of hunting, sharing stories and game meat with friends and encouraging them to join some future hunt. An unsuccessful hunter, on the other hand, may only recall the cold, wet, early-morning misery associated with a failed hunting trip, feeding forward this negative information and thinning ranks of future hunters.
Over the course of decades, as the social changes play out, they can lead to a dynamic situation where surges in the popularity of hunting can overlap with down swings in the animal populations -- an effect that has never been appreciated before. The effect is compounded, according to Fryxell, if wildlife managers respond by changing hunting quotas too slowly or incrementally.
"The most important take-home lesson is that we need to recognize the potential for our current resource management practices to unintentionally exacerbate variability on wildlife population abundance," Fryxell said. "Perhaps there is room for discussions about better ways to do it."
According to Ray Hilborn, an ecologist at the University of Washington who was not involved with the research, the result is important because it shows the pitfalls of moving too slowly to regulate a population.
"We have to look both at the biology of the system being managed and at the management itself," Hilborn said. "One of the key factors is how quickly the regulators respond."
For some populations, annual adjustments to hunting regulations seem to be enough. In New Hampshire, Gustafson said they keep track of the age and sex of the deer killed in every hunting season and then adjust accordingly. After a particularly bad winter, they might shorten the coming deer season by a few days, which keeps the population fairly consistent said Gustafson.