We built it…and they came! The Ohlone tiger beetles, that is.

Me scraping a patch to create bare-ground habitat for the Ohlone tiger beetle (photo: Leighton Reid)

I got some good news this week- my paper on scraping the ground to create Ohlone tiger beetle habitat was published in the Journal of Insect Conservation! Click here to read the abstract and email me if you’d like to read the whole paper. My advisor didn’t particularly like the word “scrape” (so we called it artificial bare patches :)), but that is pretty much what we did: scraped the ground free of vegetation. For one study, I did this manually (with lots of help!) and for the other study, I used a tractor (much easier)!

Tractor scraping ground to create bare-ground habitat for the beetle (Photo: Dave Roe)

The Ohlone tiger beetles require bare ground, as I’ve mentioned in past posts, to hunt, find mates, and lay eggs. This last point is important because if they don’t have any suitable bare-ground habitat to lay eggs, the population will decline in a big way. So, we tested whether human-created bare ground, or scrapes as I call them, will increase the habitat the beetles have to lay eggs. We tested this by scraping the ground and then checking the scrapes for eggs, or larval burrows, at the end of the breeding season. We found that the beetles will lay their eggs in the scrapes EIGHT times MORE in the scrapes the in the adjacent control habitat. Way cool, so scrapes help in a big way! We can create habitat for this endangered species!

One of my helpers, fellow grad Sharifa Crandall, scrapin' away (photo: Leighton Reid)

We also tested whether distance from the main beetle area mattered. To do this, I created a set of scrapes that radiated out from the central habitat patch at distances of 10 m, 50 m, and 100 m. I found that even at 100 m from the main habitat area, the beetles will fly out and lay their eggs if there is bare ground present!

We also tested whether compaction of the scrapes change the number of times beetles used them to lay eggs. We found that compaction did NOT matter, it was all about the bare ground! This was really fun work and shows one way we can combat habitat decline and management for endangered species recovery. We also showed that the scraped work for at least two years so scrapin’ every third year is one way to increase this remarkable species.

About tcornelisse

This entry was posted in Conservation solutions, Insects!, The Ohlone tiger beetle and tagged , , , , , , , . Bookmark the permalink.

10 Responses to We built it…and they came! The Ohlone tiger beetles, that is.

  1. Linda K says:

    Written very well.

  2. This is great work. I’ll email you to get a reprint.

  3. tcornelisse says:

    Thanks Ted! Glad you got the paper 🙂

  4. sfbaywalk says:

    I have wondered about the turf damage caused by feral pigs. Do you suppose this suggests a “positive” environmental effect of the wild pigs? Do areas rooted up by feral pigs also provide habitat for your beetles?

    • tcornelisse says:

      They do! Every year feral pig scrapes provide the beetles with egg laying habitat. The gophers do as well. In the beetle habitat areas, there are 1-2 feral pig scrapes about 1 m^2, so not too many, and it seems to provide disturbance for native forbs to grow as well (otherwise, the areas is full of invasive grasses).

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