Cats on the prowl

Cats on the prowl

Have you heard more about cougars on Vancouver Island over the last few weeks? Farmers in the province have reported losing dozens of lambs in the past two months. Our lead researcher on the deer project, Dr. Jason Fisher was interviewed on CBC Radio’s “All Points West” to talk about the BC Conservation Officer Service’s suggested mitigation strategies for preventing cougar attacks. Find out more at

Photo (right): Pixabay 

Are those collars too tight?

Are those collars too tight?

A big thank you to Dr. Adam Hering and team of volunteers who have just finished a month of collar and welfare checks for the does in the Oak Bay Urban Deer Research Project.

Through the winter we sometimes hear from concerned community members about collars on does that appear too tight. We are very grateful for all reports and take all concerns very seriously however, as Dr. Hering explains, there are many situations when collars look concerning from a distance but once he is close, or is able to immobilize the doe, he is able to determine that the collars are not actually problematic.

Dr. Hering has kindly provided information and a video (to the right) on how collars fit and why they can appear to be too tight:

It can in fact be quite difficult to truly assess how tight a collar is until I have my hands on the doe and fingers under the collar. In the years we’ve been doing these collar checks I have elected to remove 3 collars due to concerns about how tight they looked. In all 3 cases, after having my hands on the animal I decided that the collar was unlikely to be causing any distress to them but I chose to remove the collars as I could see why, from a distance, they could appear concerning. One doe did have a bit of moisture dermatitis on her skin under the collar and so I was happy I took it off and am always more than happy to take off others or replace them with looser fitting collars if I am concerned. It’s always a balance between making it tight enough that it doesn’t get caught on things or get feet caught under it when they scratch their neck and ears with a hind hoof and making it loose enough to not cause distress.

When I fit collars I take neck circumference measurements. Having done this over multiple years, on animals of all ages and throughout the seasons, I have found that the neck circumference only varies by a few cm once a female Columbian Blacktail deer reaches physical maturity. That’s based on the ~250 black tail deer I have captured throughout the Oak Bay and Esquimalt immuno-contraception (IC) programs.

What happens is that the does thicker winter coat grows in and makes the collar look tighter than it is. It can also happen that the collar may get pushed down the neck a bit when walking through shrubs, to a spot on the neck where the neck circumference is slightly greater (their neck is conical in shape) and the directionality of the hair on their neck prevents it from sliding back up where it was originally installed. They can, however, scratch their neck with their hind hooves and can sometimes slide it up that way.

I also get notified by Oak Bay Public Works any time one of our marked does die. I check them all and do post mortem exams on most that die without obvious evidence of vehicular trauma. I have yet to see an animal with a collar that has given me true cause for concern that it was impacting their wellbeing but I’m always on the lookout for it. I hate the idea that something I’ve done could be causing undue distress to one of the deer.

Doe #30 was one doe that a community member expressed concern about a too tight collar. Despite our time in the field in March, we didn’t manage to locate her, likely because there’s been construction in the area she was first tagged which may have caused her to move on from that location. Doe #30 was first captured in September 2019, when she was given her first round of IC and fitted with a collar. I estimated her to be a mature deer of 3.5 years of age at the time, and I have given her 2 booster vaccines since then with the most recent one being in fall of 2021, and I was not concerned at those times that her collar was causing her any issues.

This season I’ve completed the allotted time (based on provincial permits) in the field looking at deer and evaluating for any with concerningly tight fitting collars. I did elect to take the collar off of #3 and replaced it with large white ear tags with the number 3 on them so that she can still be identified if seen on one of the wildlife cameras – this is important for the research. On this individual, after having my hands on her it was my opinion that her collar was not problematically tight but it had caused a bit of minor hair loss/chafing which I think is a bit inevitable with collars. But given the opportunity, I elected to remove it given the number of concerned messages we’ve gotten.

In all other instances, I felt comfortable with the collars I saw and didn’t feel that any of them justified repeated capture to verify that they were fitting ok, therefore no other captures were performed.

Here is a link to a video that I took of one of the animals who is wearing a GPS collar. The collar in the video is fit on her neck similarly to the rest of them however it looks less tight because the weight of the GPS has caused the collar to slide around a little bit resulting in some hair loss – therefore you can see how tight the collar actually is against her neck without the surrounding hair obscuring the view.

Thank you to all of you who have taken the time to share your concerns – we follow up on every doe that is reported and we appreciate that the welfare of the deer is important to you as well as us!

The partnership continues!

The partnership continues!

We are happy to confirm that another year of provincial and municipal funding has been approved for this multi-year research project on urban deer and the impact of immuno-contraception (IC) as a  deer population management tool.  The Provincial Urban Deer Cost Share Project (PUDAC) has accepted the 2022 application prepared by the UWSS on behalf of Oak Bay.

In 2022 the data collection and analysis will continue, allowing our scientists to determine the impact of the decrease in fawn abundance on the adult deer population, as fewer fawns will be maturing into adulthood.  You will also see our field team out and about in their flashy orange vests, in early to mid-April, checking on collar fits and anything else that may need our attention.  We’ve really appreciated community eyes on Oak Bay’s deer, letting us know if a collar appears too snug, or if one of the tagged deer has an injury.  Whenever possible, we really appreciate photographs (taken safely) and locations, which can be sent to

The results are in once more!

The results are in once more!

Expanding on the 2019 findings of where deer can be found in Oak Bay, we have been able to identify that deer hone in on areas with lush green vegetation and large-sized residential lots (as well as parks, green spaces, and golf courses). Results of our research to date indicate that the conversion of the historic drought-resistant Garry oak ecosystems into the lush, landscaped urban environment of Oak Bay is likely supporting an urban Columbian black-tailed deer population more than the native Garry oak ecosystem would.

Additionally, after just one year of immunocontraception (IC: in the fall of 2019), the relative abundance of fawns decreased by nearly 60% in 2020. The adult deer population has stayed largely constant over the first year of IC (approx. 100 deer in all of Oak Bay), but the decrease in the abundance of fawns should result in a decrease in adult deer as fewer fawns will be maturing into adulthood.

For more information, please go to our research page:

We’ll keep you updated!

2021 Oaky Bay results