Wednesday, October 02, 2013

Deer, Coyote and Fox

Tomorrow, Thursday, at 8:30am in Town Hall on Witherspoon St, Princeton's Animal Control Committee will meet to discuss options for controlling the population of deer and, for the first time, coyote and fox as well. Reports at Planet Princeton and the Princeton Packet provide some background, though the reason why fox numbers would need to be controlled remains a mystery. The population of predators like fox tends to be cyclical. As rabbit or other prey numbers increase, the fox population increases, which in time greatly reduces the prey population, which then causes a crash in fox numbers. Low predator numbers then allow the prey population to increase again, and the ten or fifteen year cycle repeats.

Background on the deer control program can be found further down in this post, and also at the "essays" tab of this website.

The photo is of four deer encountered at dusk at Herrontown Woods recently. They had been lying in the field before I came around the corner of the Veblen House. They are beautiful creatures, and encountering them in the woods can be magical. That truth does not erase the other reality, which is that when their numbers grow unrestrained, with none of the predators that historically provided control, their appetites can do tremendous damage to a woodland. Because their tastebuds have not evolved to take more than an occasional nibble out of the abundant non-native species that have invaded woodlands, they feed heavily on what few native shrubs and herbaceous plants can be found in the woods, further shifting the woodlands to inedible exotics.

The two spicebush in the photo tell the story of how native flora have begun to rebound as deer numbers have come more into ecological balance. Spicebush is a native shrub important to wildlife for nesting and food. Because of its strong taste, it's not one of the deer's favorites, but an overabundance of deer forces them to eat it. You can see the main stem and then many new stems growing up from the base. Back in 2000, spicebush were struggling to survive, sustaining themselves with one stem that was too tall for the deer to defoliate, while new shoots would be repeatedly eaten down to stubs by deer. Only after the intense browsing pressure was brought down through professional control could the many new stems grow to maturity, and the shrub once again fill its niche in the forest.

Below is some background on the deer issue that I wrote after Princeton suspended its professional deer control efforts for a year, back in 2011, before resuming funding.


Talk to most any land manager in New Jersey about what poses the biggest threat to biodiversity, and they're likely to say deer overpopulation. 

Traditional predators of deer, such as wolves and mountain lions, were long since extirpated from the region, resulting in a highly destructive ecological imbalance. Since the imbalance is human-caused, it's important that deer policy fill the void left by banished predators. For ten years, Princeton Township lived up to that responsibility to compensate for a broken food chain. Since hunters were not proving sufficiently effective in controlling deer numbers, professionals were brought in each year to reduce the deer population to a more ecologically sustainable number. The harvest went to food kitchens to feed the poor. The policy was controversial, particularly in its first few years, but the ecological and public safety benefits were clear. It can also be said that life for the remaining deer was greatly improved, as their preferred foods were given a chance to rebound.

According to data obtained from Princeton Township, roadkill reached a peak in 2000 of  342 deer killed on the roads. In that same year, Princeton township hired professionals (White Buffalo) to reduce the size of the deer herd. White Buffalo took 322 deer that first year. By 2010, the number they were able to cull had dropped to 148. The lower number reflects a successful reduction in the deer herd. Deer killed by amateur hunters went from a high of 255 in 2000 down to 68 in 2010. 

The primary goal of this ten year program was to reduce the number of collisions with deer on the road, and annual roadkill numbers reflect the success of the program, dropping from the high of 342 in 2000 down to 68 in 2010. Also noticeable during this ten year program was a marked rebound in native vegetation in Princeton’s nature preserves, as browsing pressure was reduced.

For the year 2010/2011, the township decided to terminate its contract with White Buffalo, to save money and to see if hunters could provide adequate control of deer numbers. Data for the year has not yet been received, but it can be pointed out that amateur hunters were unable to control the deer population in the 25 years leading up to 2000, when roadkill numbers rose steadily from 68 in 1975 to 342 in 2000.

Even from an animal rights point of view, one could argue that the program has been a success, actually reducing the total number of deer killed annually in Princeton Township over time. In 1999, the year before the professionals were brought in, 555 deer were killed in the township by vehicles and hunters. In 2010, after ten years of professional deer management, the total number killed by vehicles, hunters and professionals had dropped to 286. With the end of professional management, history suggests that that number will begin to rise.

A 2002 NPR piece did a very good job of reporting on Princeton's investment to bring the deer population into greater ecological balance. It reported that 16,000 deer were killed on the roads of NJ back then.

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