Deer Immunocontraception Project

Update on the Village Deer Immunocontraception Project:


The deer immunocontraception research project, a collaboration between The Humane Society of the United States, Tufts-Cummings School of Veterinary Medicine, and the Village of Hastings-on-Hudson, enters its seventh year in 2020.  Beginning in 2014, the research team captured, ear-tagged, and administered PZP immunocontraceptive injections to 69 adult does in the Village, with the last captures carried out in winter 2017.  These initial treatments were very successful:  whereas more than 90% of Hastings does were producing fawns each year prior to PZP treatment, only 15% of PZP-treated females produced fawns in each of the two years after treatment.  

A crucial element of the study is to test how long contraception can be continued by a PZP booster given directly by dart in the fall 2.5 years after initial treatment.  Booster-darting was completed this last autumn (2019).  Because some ear-tagged animals had died or disappeared before boosting, 29 of the original 69 ear-tagged does received boosters between 2016 and 2019.  So far, only two fawns have been born to boosted does in two years after treatment, for a fawning rate of 8% -- which is very encouraging.  To see how long the booster’s contraceptive effects last, researchers will continue to monitor these does over the next several years. 

The other focus of the study is the one of most direct interest to residents – the effects of PZP treatments on the number of deer in the Village.  Preliminary analysis of population trends has been encouraging – fawn numbers are down by 70-80% relative to the numbers present at the beginning of the study, and doe numbers down by about 40%.  These trends still need to be confirmed by analysis of camera trapping data, but are consistent with anecdotal feedback from Village residents, as well as with the number of deer-vehicle collisions in the Village, which were more than 2x lower from 2017-2019 as compared to 2013-2015. The exception will be residents on the Village’s edges, especially near Dobbs Ferry and Yonkers.  Many deer living at the Village edges escaped capture and treatment because their home ranges extend into adjacent communities, and most of the fawns observed by the research team were found there.

The Village looks forward to continuing to work with residents, the NYSDEC, the research team, and other stakeholders about whether and how deer contraception might be integrated into the Village’s long-term deer conflict management plans.

We are asking residents to again help us keep track of the deer this fall by sending deer sighting photos, along with the date and time of the observation, to <>. If a photo is not possible, please include the description of what was observed (i.e if tagged or not, tag number, size/age/sex/ group size, etc.). 

Thank you for your continued interest and support.

Background Materials
Deer and Deer Reproduction and Contraception Information