Sky Island Scarcities Solved?

Our annual visit to the Sky Islands region of Southeast Arizona is one of our favorites. It is an incredibly diverse tour, averaging nearly 200 bird species plus dozens of reptiles, amphibians, mammals, butterflies, and other exciting wildlife! Our tour in 2021 (eBird trip report here) noticed something lacking though… Where were the Canyon Wrens? Where were the Rufous-crowned Sparrows? Where were the Black-tailed Gnatcatchers? These 3 species are fairly synonymous with the region: Canyon Wrens are often heard belting out their iconic, cascading song from canyon walls (we found 0); Rufous-crowned Sparrow can be found skulking through lush cactus-scrub (again, we found 0); and Black-tailed Gnatcatchers should be busily defending their territories along desert washes (we found 2). Were we doing something wrong? That didn’t seem likely… these birds should be encountered regularly without much effort at all, and we covered all the classic locations! So what gives?

I left Arizona last August feeling confused and curious, but now we have an answer: the birds simply were not there. A major drought in 2019 had devastating effects on many of the region’s breeding bird species; and Canyon Wren, Rufous-crowned Sparrow, and Black-tailed Gnatcatchers were hit particularly hard. Follow this link to a fascinating article by Tucson Audubon’s Tim Helentjaris who crunched the eBird data from 2019, 2020, and 2021. In short, Canyon Wren had a shocking 75% decline in sightings from 2021 to 2019; sightings of Rufous-crowned Sparrow and Black-tailed Gnatcatcher declined by 40% and 50%. Other classic birds oflike Hutton’s Vireo, Elegant Trogon, and Cassin’s Sparrow showed major declines as well – indeed, all species which we had difficulty tracking down on our 2021 tour.

So what does this mean for the birds, and what does this mean for us birders? Well, it isn’t a secret that birds living in these extreme environments can go through some extreme population fluctuations. However, the sudden decline caused by this 2019 drought is very striking. In the Tucson Audubon article, Tim drives home the point that climate change is to blame for these increasingly wild patterns and that is sadly a theme we are seeing worldwide. As birders we can continue to venture out in the field, documenting our sightings through eBird, and doing our part to fight climate change at home. In the meantime, I hope we will see populations rebounding some this coming August during our next tour.

Rufous-crowned Sparrow peering out from its brushy domain, photo by Alex Lamoreaux