Sargent's view: With deer come tick-borne diseases

Bill Sargent/PhotoA doe scampers through a North Shore yard. 

“Merrimac Sports is an all-round sporting goods store where you can buy rods, reels, bait, Christmas trees and even fresh lobsters sitting in a quietly burbling water tank.

Don Newcomb is the friendly owner of the emporium who explains, “We are one of the only stores left who tag deer out of the goodness of our hearts. But today the inspector is in Westborough, Massachusetts.” 

“The hunt ain’t fair with all this snow. Too easy to track the deer. Today we’ve had 10 deer, 18 yesterday and 25 the day before during the storm,” Newcomb said.

“It’s also not fair because the males just came into rut and they are exposing themselves, peeing all over the place and chasing the females out into the open. 

“I used to help dress the deer. But now I say, ‘Ah just do it yourself.’ I ain’t getting near a tick. Had enough of those buggers all over me.”

National statistics tell an even more ominous story. People are catching more tick-borne diseases every year. In Massachusetts alone, there were only about 1,000 new cases of Lyme disease in 1994. 

Now, more than 67,000 Massachusetts residents are contracting at least seven known new diseases carried by ticks every year. That is a 6,600% increase in just 25 years. And of the 300,000 new cases reported nationwide every year more than 21% of them occurred in Massachusetts.

During those same 25 years the deer population in Massachusetts has also burgeoned. In the mid 1900s there were only 10,000 deer in eastern Massachusetts. That comes to about five deer per square mile.

Today there are about 50,000 deer in eastern Massachusetts – which comes to more than 20 deer per square mile or about five times as many deer as 25 years ago.

And each deer may have up to 30 ticks hanging like bloated grapes from its body and each female tick can lay as many as 4,000 eggs from a single meal of deer blood. That amounts to millions of new disease-carrying ticks that are added to the population in eastern Massachusetts every year. 

The main reason that the ticks and deer have ballooned to such unhealthy numbers is that almost 50% of the towns in Massachusetts now ban hunting on public lands and require that hunters obtain written permission to hunt on private property.

The surge in deer numbers gives ticks free reign to reproduce, but if the number of deer was reduced to below the natural carrying capacity of the land to support the deer, ticks would not be able to get enough blood meals to lay their eggs.

The natural carrying capacity of the land is about 13 deer per square mile. Above that number, the deer harm the forests by over-browsing. Below that number, the forests flourish and the number of ticks and tick-borne diseases drop precipitously.

So if Massachusetts reduces its deer population to what it was in 1994 it could drastically reduce its number of tick-borne diseases.

But it is unlikely that will happen. Public sentiment is moving away from hunting and towns are adopting more restrictive measures.

Some have suggested arming hunters with birth control medications that they could shoot into female deer. But it turns out that is far more expensive than what hunters call vaccinating them with lead.

It is ironic that in this age of modern biotech contraception and vaccines, the cheapest and easiest way to reduce tick-borne diseases is to reduce the deer population.

People don’t like to think of killing defenseless and beautiful animals like deer, but if they understand that if we continue to let the deer populations explode, the deer will become unhealthy and starve, forests will wither and die and up to a million more humans will have their lives ruined if not ended by the rapidly expanding host of new tick-borne diseases which we will have inflicted on ourselves.

Bill Sargent is a North Shore science writer and contributing columnist. His most recent book, 20,000 Years on the Merrimack River is available in local bookstores and through, and at



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