Year 5 field Operations report (2019-2020)

Clifton Deer 5th Season Report

Clifton Deer finished its fifth season of Fall-Winter field operations on February 8th after the capture and surgical sterilization of 9 more does. That brings to 79 the total number of deer treated and tagged over the past four years.

The annual post-operations population survey conducted in February found that:

  • ~98% of the adult females in the study area are now sterilized;
  • the fawn recruitment rate (# of fawns per doe) dropped from .65 in 2016 to .10 in 2020; and
  • the total number of resident deer in the study area has fallen over four years by 28% from ~99 (Winter 2016) to ~72 (Winter 2020).

If immigration remains as low as it has been so far, the population should continue to decline through natural attrition.

By these core measures—low immigration and a high percentage of sterilized does — the study so far is proving that limiting fertility can work to reduce and manage deer populations in urban settings with porous boundaries.

Sadly, one of our does died unexpectedly while recovering from an uneventful surgery, probably as a reaction to anesthesia. This was our first capture mortality since 2015.

Three research questions still need to be answered:

  • How long will it take to lower the numbers to an eco-sustainable level through fertility control alone?
  • Will immigration of new deer into the study area remain low as the resident population drops?
  • Can this approach be managed cost effectively?

The first two questions can only be answered with time and continued study. Our tagged does have had an extremely low mortality rate to date, probably as a result of Clifton’s relatively low traffic speeds and the general good health of our herd. This means that while immigration of new deer has been low, our population decline so far has been slower than at other study sites, but steady. 

The answer to the third question–can sterilization be cost effective–increasingly appears to be “yes.”  Effectiveness is being established with the steady decline in population; and costs are being reduced dramatically with continued development of skilled local volunteer resources. Clifton Deer is projecting next year’s operating budget to be less than 30% of the first year’s.

Cost reductions are largely attributable to two successes. First, Clifton Deer’s connection to UCAN, a state-of-the-art local spay-neuter facility for dogs and cats, and its relationship with UCAN’s veterinarian surgeons and staff, has greatly deepened our local base of volunteer medical expertise and eliminated the need for our contractor, White Buffalo,Inc., to transport and set up “MASH-style” surgical facilities on site each year. Second, after three years of apprenticeship and training, our local volunteer darter this season demonstrated his readiness to take a leadership role in our operations by finding and capturing our last, most elusive does. Thus, the program has greatly reduced its heavy dependence on the hands-on expertise of White Buffalo.

None of this would have been possible without generous grants from, among others, The Animal Welfare Institute, The DJT Foundation, and The Kenneth J. Scott Foundation, a Key Bank Trust, and donations from individuals and Clifton businesses over the past 5 years.  We are grateful to each person, from the 9 year old deer lover who gave $1 to the frustrated gardener who gave $2,000, who has chosen to be part of the solution.

We also owe the Program’s success to those Clifton homeowners who, with patience and good humor, host bait stations in their yards – allowing us, and the hungry neighborhood deer, to come and go for weeks on end.   

And we can’t imagine where we would be without our volunteers:  Those hearty souls who spend long nights waiting…and waiting…and waiting to spring into action when the “dart out” call comes from the capture specialists. These volunteers include the transport team who rush out into the cold and dark to carefully carry a sedated doe from woods and ravines; the skilled and big hearted surgical team that expertly spays her; and the recovery team that watches silently in the cold till she wakes and gets back on her feet to re-join her companions.

And finally, a special thanks to UCAN, whose partnership has contributed comfort, expertise, and important cost savings to the Program.


An exciting, innovative, and humane deer fertility control pilot program