Naturalist Segment: Ohlone Tiger Beetle

For this month's Science Committee Naturalist Segment we will learn a bit from the experts about the Ohlone tiger beetle! Keep reading to learn more about how you can spot one of these special beetles in Santa Cruz!

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QUICK FACTS Scientific Name: Cicindela ohlone First Discovered: 1987, named and categorized in 1993 Habitat: Endemic to Santa Cruz, CA Status: Endangered since 2001 The Ohlone tiger beetle (OTB) is one of the ecological jewels of Santa Cruz, being endemic to this area, meaning it only lives in a handful of areas in the Santa Cruz Mountains. According to the Center for Biological Diversity, OTBs are "ferocious and agile predators that seize their small prey with powerful sickle-shaped jaws." Adult beetles prey on small arthropods, such as spiders and ants. The OTB has a life cycle of two years, and is active mostly in the winter and spring (January-May), which is unlike any other tiger beetle species, which are active in the summer and fall. OTB's are known to enjoy the trails we like to ride as places to dig burrows and lay their families (well, one egg at a time). Once the eggs are in larval phase, they become predatory as well, and lunge and seize passing invertebrate prey from their burrows. Larva patiently waiting for prey... Ohlone tiger beetles have been called majestical, beautiful, even cute. The data (Cornelisse et al. 2013) tells us they actually enjoy "disturbed" areas, or places where cows may tread, and pathways where humans may ride bikes, as it creates the open surface (dirt), they need to dig their homes. Knowing this, you might feel pretty lucky knowing it may not be as hard as you once thought to spot one of our ecological crown jewels, so to speak. Of course, we must be very careful when riding in their habitat to look down and be sure not to crush them, but don't worry, we'll get to that later. Check out those burrows! Photos from Conservation of Biodiversity To learn more about the awesome bugs, we decided to head straight to the experts, who spend a lot of time researching, protecting, and educating the public on Ohlone tiger beetles. We interviewed Alex Jones, Manager of the UCSC Natural Reserve. What is the status of Ohlone Tiger Beetles at the UCSC Natural Reserve?

• • The Ohlone Tiger Beetle is found in two areas of the UCSC main campus--within the Marshall Fields complex in Upper Campus and "Inclusion Area A" (IAA), also known as Mima Meadow or Spring Ranch, west of Empire Grade and the UCSC Arboretum. Of these areas, only West Marshall Field, just SW of Twin Gates, is within the UCSC Campus Natural Reserve (2005 Long Range Development Plan land-use designation). Dick Arnold (Entomological Consulting Services) conducted surveys within a different portion of Marshall Fields from at least 2000-2017 (Arnold and Knisley 2018) and found a similar trend to what he observed during surveys of IAA from 2005-2017 (Arnold unpublished reports). According to these surveys, populations of OTB in both area declined during the early-mid 2000s, rose slightly until the mid-2010s, and have dipped slightly again.

Where can one most likely see them?

• • The Ohlone Tiger Beetle is found in two areas of the UCSC main campus--within the Marshall Fields complex in Upper Campus and "Inclusion Area A" (IAA), also known as Mima Meadow or Spring Ranch, west of Empire Grade and the UCSC Arboretum. Adults are active between January and May, with increased activity on sunnier, warmer days.

What efforts are being made to protect them at the preserve?

• • Prescribed fire can reduce thatch (built up dead vegetation) and increase the bare ground surfaces that the beetle needs for hunting, basking, mating, and larval burrows; we burned portions of the Marshall Fields complex in fall 2017 and fall 2018 (different areas in different years). Grazing can also help by reducing vegetation and creating bare ground; currently grazing occurs in IAA but not in Marshall Fields. We have installed some simple signs asking bikers to slow down on trails through OTB habitat. We will also be installing some "artificial scrapes" in OTB habitat on campus this late summer/fall. These scrapes, done by hand or by heavy machinery, create more bare ground that the OTB can use for hunting, basking, mating, and larval burrows (Cornelisse et al. 2013).

What can we (as trail users) do to help?

• • In the past, UCSC has fenced off trails during the winter OTB adult season to protect them from being run over by mountain bikes. This, however, allowed for vegetation to grow over the trails, reducing important OTB habitat. We therefore no longer fence off trails for OTB management (though we sometimes do fence them off during extended wet periods where coastal prairie trails get excessively damaged from overuse). We recently installed simple signs asking bikers to slow down to 5 mph along trails used by OTB. Former UCSC PhD student Tara Cornelisse showed that slowing down to 5 mph or less on trails used by OTB reduces direct mortality and also reduces the frequency and distance that adult beetles will fly in reponse to disturbance (the further the flight, the more energy wasted; Cornelisse et al. 2013, Cornelisse 2013). Every winter we find several crushed OTB along trails through OTB habitat; by slowing down, or even dismounting in these areas, you can help this critically endangered species in a very direct way!

Anything else you want to add?

• • These are really interesting, beautiful creatures that exist only in a handful of places on Earth, all in Santa Cruz county. We are really lucky to call them neighbors, and with a little effort and education we can all help protect them.
  • Check out the following webpage for some links and basic information (you can share this in the article if you want): https://ucsccampusreserve.ucsc.edu/maps-habitats-organisms-stewardship/otb-page.html

Recently, MBOSC hosted a naturalist night talk at the Santa Cruz Museum of Natural History. Our talk was called "Natural History of Trails" and featured three speakers. One was Alex Krohn, Assistant Manager of the UCSC Natural Reserve. Hearing his passion for the Ohlone tiger beetle, and all wildlife in the reserve, rejuvenated our spirits and reminded us one of the main reasons we're all out there in the first place: to enjoy nature. What does this have to do with OTBs, aside from them being so awesome? His advice? Slow down. Remember to look around at all the amazing wonders around you, including keeping your eyes peeled for OTBs. During OTB active time, winter and spring, UCSC students and staff put up fencing and signs warning trail users to slow down, and/or close off areas to the public altogether. Please respect these signs and closures!