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  • Monitoring pygmy owls helps County biologists balance conservation efforts with development plans

    The trilling of a bird call rang out from a portable speaker. A group of biologists stood with their hands cupped around their ears listening intently for the return call. 

    “I’ve got him!” shouted Aaron Flesch, a research scientist with the University of Arizona, as the group set off in the direction of the call, in search of the elusive cactus ferruginous pygmy owl.  

    Flesch, along with Pima County wildlife biologists Ian Murray, Jeff Gicklhorn and Amanda Webb with Pima County’s Office of Sustainability and Conservation tracked the bird to a low-hanging branch of a mesquite tree, where the lively owl was poised to defend its territory from an invisible intruder. The County and UA work in partnership to monitor pygmy owl populations. 

    The group was out early on an autumn morning on County-managed ranch property near Three Points to monitor cactus ferruginous pygmy owls, a diminutive bird of prey about six or seven inches tall, which lives in the holes excavated by woodpeckers in the saguaros that dot heavily wooded regions of the Sonoran Desert. 

    They were there doing the County’s due diligence under the Sonoran Desert Conservation Plan (SDCP) and Multi-species Conservation Plan (MSCP), the part of the SDCP that addresses U.S. Fish and Wildlife Service endangered species compliance. As part of this compliance, the County is required to monitor a variety of species on lands the County either owns or manages. The County’s SDCP provides a road map for balancing conservation efforts with development plans to maintain an economically vigorous and fiscally responsible community. 
    Pygmy owl
    “An important goal of the SDCP is to make sure that our area’s impressive biodiversity, including the pygmy owl, is preserved,” Murray said. “Other key goals address preservation of our area’s rich cultural heritage and conservation of working ranches.”  

    Through this smart-growth plan, the County has been able to provide for 44 native plant and animal species and their habitats, across more than 258,000 acres of Sonoran Desert landscape, much of which is permanently protected. 

    The pygmy owl, which was a catalyst for the early community discussions leading to adoption of the SDCP, has many quirks and interesting behaviors that researchers have documented. Flesch explains how most species of owls are nocturnal but that the pygmy owl has adapted into a largely diurnal niche, and prey upon lizards, insects, small rodents, and birds that are active in daylight. They are also active during full moons and during twilight. 

    Flesch described pygmy owls as opportunistic hunters, flittering from tree to tree, mostly palo verde and mesquite, where they lay in wait to swoop down on unsuspecting prey. 

    “These birds seem to have co-evolved with mesquite trees,” Flesch said.

    When monitoring the birds, Flesch mimics their calls and waits for the owls to respond. Because the owls, despite their size, are a formidable predator, they are frequently mobbed by smaller birds that harass and hector the territorial owls as they fly in for a look.  At times the agitated behavior and alarm calls of smaller birds can give away the location of an otherwise camouflaged pygmy owl.

    Pygmy owls in the wild got a lot of attention beginning in the 1990s. As part of what some called “the development wars,” opponents faced off over the future of growth in the region, with the development community on one side and environmentalists on the other. 

    Environmentalists had staked a claim on the pygmy owl as a species in need of protection from further urban encroachment. These disputes often landed in the courts, where environmentalists sought to halt developments that potentially had adverse impacts on pygmy owl habitat. The development community saw these efforts as obstructionist attempts to drive up costs and freeze lawful construction activities.       

    Although the disputes at times grew pitched, ultimately the two sides reached an accord. That detente, the landmark Sonoran Desert Conservation Plan, struck a balance between conservation and development interests and effectively remade urban development policies in Pima County as we know them.  

    The fulfillment of the SDCP as implemented through monitoring and management of the County’s mitigation lands offered a measure of certainty for environmentalists, who wanted protections for animal species and open spaces, and the business community that needed to know the established, reliable development rules couldn’t needlessly stop proposed projects with third-party lawsuits. 

    More than two decades since this small owl played a central role in sometimes heated discussions that pitted different parts of our community against one another, and more than four years since the MSCP went live, the community has shown widespread support for the conservation while ensuring development can continue in less environmentally sensitive regions. The work of researchers with the County, University of Arizona, and Arizona Game and Fish has identified numerous additional home territories of pygmy owls around the County and southern Arizona that were previously unknown.

    And while habitat loss has certainly impacted population, and 
    the owl’s survival has been a regional success story, Flesch notes some challenges remain. Hotter temperatures and drier summers result in nesting pairs producing fewer young, which could negatively impact their populations if these trends become too extreme.  Continued monitoring of known owl territories on County managed lands will help to determine how they are faring in the face of an uncertain future.

    Back in the wilds of Pima County, Flesch and company followed the little female owl as it hopped from tree to tree, seemingly observing as much as being observed. Then, as quickly as she appeared, the owl flittered back into the thick of the desert, sticking just below the canopy of trees. 
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