Non-lethal Deer Management Project
in San Jose
A deer sterilization project starting in 2013 was approved by the California Department of Fish and Wildlife to control the deer population at a retirement community in San Jose, the Villages. Some does had ovariectomies while others had tubal ligations. A cull using archers was the original plan, but with a large public outcry outside of the community and concerns about public safety, the sterilization project was approved. Although the initial cost of the sterilization approach was higher than the use of archers, no follow up has been required going into 2021. Culls using archers often require annual maintenance and can be difficult to execute given safety restrictions and deer learning to evade the archers. Over time both approaches may cost about the same with large variations in cost related to factors such as the to the use of volunteers.
This article by Hasan Z Rahim gives some history of the project. This peer reviewed research paper also provides a summary and a deer population model. The paper describes a startling difference in the results at this site and a similar project done by Cornell University, where they reported a dramatic increase in the buck population. As the data reported below show and as discussed in the research paper linked above, the buck population at this location fell dramatically.
Deer Count: At the start of the sterilization project in January, 2013, the deer count was 175 with 105 does and 70 bucks, falling to 47 deer in spring, 2019, with 42 does and 5 bucks. Reporting stopped after Spring, 2019.
Spring, 2019 deer count (April): 42 does and about 5 bucks, 47 deer including a few does photographed (some on this page) after the count. All of the sterilized does had been tagged, making them easy to count and making it easy to spot any untagged does that might have migrated into the community.
As shown at right, openings were created in fencing to encourage migration of new deer into the area in an effort to restore some of the population. Two fawns were later born from sterilized does, sterilization is not typically 100 percent effective, but one was a buck and one died at a young age. Over the three years of this project, no does permanently entered the community but one doe spent some time near one of the openings in the fence.
It was expected that deer from outside the community would migrate in, so all does were sterilized, but no new deer migrated into the community. The population fell below a target the community later set. This project, supported by San Jose State University, started in 2016 with a goal of understanding why there was no migration of deer into the community using trail cameras to monitor the deer.
Spring, 2018 deer count: 49 deer inside the community, 42 does and 6 or 7 bucks in April. A few deer are spending time outside the count area.
Fall, 2017 deer count: 55 deer, 49 does and 6 bucks in August.
Two Fawns Born The trail camera photo below verified the reports of the first fawn seen in the area for years, pictured below her mother, Doe 100. See more on her page. According to the records, Doe 100 had an ovariectomy at a very young age. Doe 100 was found dead on September 10, 2016, no apparent cause. She seemed fatigued in the last video recorded.
A test on one of the approximately 10 deer that died starting in September, 2016, came back positive for Blue Tongue, a hemorrhagic disease that is not infectious to humans or other deer, but is spread by insect bites. The video below shows the fawn nursing, clear evidence that this was her fawn.