My first blog entry in this series focused on the very first important step in catching wild cats for research: learning where there may be wild cats to study! Once you've learned where there are cats to study, you need to also have a good study question that you are going to focus on that requires capturing animals. So this is a good chance to talk a little bit more about my research and why I ended up studying bobcats across the Santa Monica Mountains.
My study focuses on how urbanization affects the health of bobcats in the urban, fragmented landscape around Los Angeles. To perform this research, I spent more than two years conducting intensive bobcat trapping so that I could collect samples (blood, urine and fecal material) to measure health indicators in our local bobcats. These health indicators are very similar to what your vet would be interested in if you took your dog or cat to a vet to do a routine check up. Your vet may collect fecal samples to check for internal parasites like tapeworm or roundworms and blood samples to test for viral or bacterial infections. With blood we can also test whether the animal has a healthy immune system and with both blood and urine samples, we can test whether the animal has normal organ function. So my aim was to evaluate these various factors in wild bobcats in the Santa Monica Mountains since for bobcats living in/near urban areas, they may be exposed to pesticides (like rat poisons), can contract diseases carried by domestic cats, may have reduced genetic health in isolated populations at risk for inbreeding, and generally can have a more stressful life since they are regularly exposed to roads and human activity.
To understand how urbanization affects these health indicators in bobcats, I needed two groups of animals so I could make comparisons between the two groups. For my first group, I captured "control" group of healthy bobcats, largely unaffected by urban development, so that I could establish baseline values for the tests I was conducting. My second group was bobcats I captured in urban areas. Luckily, the Santa Monica Mountains offers some areas (like the State Parks- especially Point Mugu State Park) where bobcats are less affected by urban development, and also some areas of habitat fragmented by urbanization but still host to bobcats. So, for my study, I sought samples from bobcats in State Parks (Point Mugu, Malibu Creek, and Topanga State Parks) as well as in urban habitat patches east of the I-405 (Bel Air, Beverly Hills, Hollywood Hills, and Griffith Park) and north of the 101-freeway in Thousand Oaks.
Now that I had a research question and knew where cats were (see previous blog post) in the Santa Monicas, I was ready to start trapping. To start getting your trapline ready, there are a few important things to know about trapping, and about the animal you are trying to trap. First, once you set a trap, it can take weeks (or months for larger cats like mountain lions) before you get a capture! A lot of people think that studying these wild cats must be a daily exciting adventure involving seeing wild cats every day at work. But the truth is that biologists studying wild cats actually very rarely see their study animals since they are solitary, territorial, have large homeranges (making it so there are few individuals in a given area) and on top of it all, are very shy and elusive!
So when you set your traps in a bobcat or mountain lion's territory, you may have to wait for weeks until a cat even walks by the trap. Of course, setting multiple traps increases your odds, but another important note- we check our traps everyday twice a day- once in the morning and approximately 12 hours later in the late afternoon/early evening! So by time alone, you are limited in how many traps you can get to during the morning before you have to start your afternoon checks. Another important element biologists must consider is that since wildcats are mostly nocturnal, we are more likely to find cats during the morning trap checks and so you want to make sure it only takes no more than a few hours to check all your traps in the morning so that animals aren't stuck in the traps unnecessarily long. For bobcats, and sometimes mountain lions, we use large cage traps that, although very safe for the animal caught in them, we always aim to minimize the amount of time animals are in the traps so they aren't unnecessarily stressed.
Because wild cats do tend to have large homeranges (about 1-3 square miles for bobcats and 60-200+ square miles for mountain lions) you also don't want to have your traps too close together. Remember that these animals are solitary and territorial, so for bobcats in a 1-3 square mile range, you may only have 2-3 animals roaming around. So ideally, you want to cover many square miles with your traps, but travelling from trap to trap then increases the time to check your traps, which you are trying to keep to less than 3 hours.
On average, I had 15-20 traps set at all times during my trapping seasons. For this number of traps set, I would definitely need two people for every morning trap check to ensure that we covered the ground quick enough. One of the great things about doing field work like trapping cats is that there can be a LOT of hiking involved! It is very hard work (I'll cover that in the next blog) as when traps are set, they are open 24/7. Everyday you must check the traps. We keep traps open 24/7 during trapping season because if a cat only walks by a trap once over a 3-4 week period, you don't want your trap closed the day the cat ends up passing by the trap! At the end of the day, it's a lot of hard work and requires a LOT of patience. For me, I enjoy being outdoors, hiking around, and doing hard work. I can be patient to wait for captures to happen, and so when they do, they are very exciting!
For the next blog I'll cover how the traps themselves are set, and after that, what happens when we get a cat!