Week 3: Small Animal Passages

Tiffany E -

Hello everyone!

A bobcat captured on a trail camera
A bobcat captured on a trail camera

My expert advisor is still out in the field working with the trail cameras, so I want to use this time to explain what my next steps are going to be. Me and another student researcher were both given 2 different hard drives at the beginning of the project (one of which has the videos of the ocelot from last summer). Our job was to initially go through the hard drives with the trail camera videos and sort them based on what they contained. Once we are done with our initial sort through we are going to swap the hard drives and go back over each others filings, and this time we are going to count how many of each animal are in each video. Although we aren’t scheduled to swap for a few more weeks, I am getting close to being done with my hard drive. So stay tuned for when we go deeper into analyzing the videos!

Now, to pivot slightly, back during my first week on-site we had a meeting with a few ASU students where we discussed an interesting and recent article about the effect of the USA-Mexico border wall on wildlife movement. The border wall connects to how infrastructure and loss of habitat connectivity is one of the ocelots’ largest threats in the wild that is actively contributing to their population decline. The article focused on how in a few parts of the border there are small wildlife passages that help to facilitate animal movement. Small wildlife passages are almost exactly as they sound- they are a small gaps of space (21.5 x 27.8 cm) in between two pillars of the border created for animals to pass through. Ocelots are likely positively affected by these passages simply because of the fact that they are likely small enough to go through them. On the other hand, larger animals like Black Bears can’t fit into these passages, which limits their movement.

The border may be a factor that is affecting ocelot’s presence here in Arizona and could be contributing to the sporadic ocelot sightings. During our meeting we considered how we could apply this article and its findings to the Phoenix Zoo’s own study in the Atascosas Mountains and what we would’ve done differently ourselves. We talked about how it would be interesting to see the effect of the large path in front of the border on animal crossings and movement. Furthermore, the Atascosas Mountains are very close to the border, so this study is extremely relevant and could be having an impact on the wildlife and populations in the region. Also, it’s important to note that this study used trail cameras to record the crossings and see how often successful crossings happen for both different types of border infrastructure and different animals1. This really shows just how versatile trail cameras can be and how they can provide a large variety of different data and information to aid wildlife conservation for all species, not just ocelots.

Until next week,

Tiffany

Citation:

  1. Harrity EJ, Traphagen M, Bethel M, Facka AN, Dax M and Burns E (2024) USA-Mexico border wall impedes wildlife movement. Front. Ecol. Evol. 12:1487911. doi: 10.3389/fevo.2024.1487911

If you want to read this article for yourself, here’s the link!

https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2024.1487911/full

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Comments:

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    arwen_h
    Hi Tiffany! I was just wondering how these small wildlife passages are made? Are they formed naturally or are they created by a certain species? Do you know any other species along the border other than ocelots that would use them?
    Olivia F.
    Hi Tiffany, since the ocelots are able to fit in these passages, is it possible that other predators will follow this path in addition to them, that are smaller than the bears that still propose a threat to ocelots, leading to the lack of ocelot sightings in Arizona, or are these passages mostly utilized for them and harmless other animals?
    tiffany_e
    Hi Arwen! the small passages are actually created by humans. We can carve into both of the border pillars near the bottom, taking out a small chunk of metal, which allows for an increased amount of space for an animal to pass through. The article I mentioned has a great image to look at if you're still confused! Yes, pretty much any species that is able to fit through the wildlife passages would/can use them. According to the article I cited, these animals include raccoon, gray fox, bobcat, coyote and striped skunk! As you can see, all of these animals are rather small, which is why they were seen crossing the border through the wildlife passage. I hope this answers your questions :)
    tiffany_e
    Hi Olivia! Thanks for your question. This is a possibility! Although, I think the larger reason that there are limited ocelots in Arizona is more due to the fact that only a few are wandering up from Mexico, rather than them being hunted by predators. Ocelots' predators include jaguars and pumas, which are significantly larger than ocelots and would be unlikely to be able to fit through the small wildlife passages. Additionally, there are so few wildlife passages that if an ocelot did happen to stumble across one, its predator would also have to be near it for it to become a problem. This was an interesting question to think about! I hope my answer brings some clarity
    Sahaas T.
    Hey Tiffany, do you truly believe ocelot sightings will increase due to the manmade passages humans have constructed so ocelots can pass through the border? Also, how many of these passages have been made for the ocelots and other species to safely traverse their way through the border?
    Elena S
    Hi Tiffany, how many passages along the border are there, and do you think that an increase/decrease in number would have a big effect on animal populations? Also, does the inability of larger animals to get through the passages lead to there being areas with a disproportionate concentration of predators in comparison to prey?
    tiffany_e
    Hi Sahaas! I'm not entirely sure if there is a direct causation between ocelot sightings and the manmade passages. But, I think that these passages definitely could be one of the many factors that impact ocelot sightings in Arizona as they may help to increase their habitat connectivity between their population in Mexico and here. In short, we can't confirm that its causation, simply due to the many different factors that affect their presence. There are not very many of these passages yet- only 13 on the border of Arizona and Mexico.
    tiffany_e
    Hi Elena! There are 13 passages along the border of Arizona and Mexico. As this study has shown, many smaller species were able to pass through, so, I do believe that an increase of these passages would benefit animal populations in both Mexico and Southern Arizona. To answer your second question, I'm not completely sure as to what the answer would be. This is definitely an interesting point to consider and study further. But, I would theorize that although this is a possibility, there's a healthy and large animal population of both predator and prey in the Sky Islands region already, so I doubt that this would be too dramatic of an issue. I hope this clears everything up for you!

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