Rio Vista: A Place that Owls call Home, May 2022

A Western Screech-Owl roosted in one of the nest boxes in Rio Vista Park from December through mid February, before unexpectedly disappearing. Weeks later, on March 24th, another owl, possibly the same one, was found in the same box along with two eggs. A check on April 9th revealed a female incubating five eggs.

Our long term HawkWatch International study of cavity nesting raptors had fourteen Screech-Owls using nest boxes in and around Tucson last year . None of those nesting owls had more than three eggs inside. This spring, the Rio Vista owl is the second nest we’ve found with five eggs, and several other nest boxes have four. Perhaps the abundance of eggs is a response to the continued effects from last year’s incredible monsoon season? Healthier habitat certainly increases food resources and ultimately a bird’s body conditioning. In addition to the Rio Vista owls, there are two other pairs known to be nesting adjacent to the Park in private residences along Cactus and Allen.

Four of the five Rio Vista eggs hatched in late April. On Saturday May 19th, the twenty-something day old chicks were weighed, measured and banded.

A feather sample was taken for future isotope and genomic analysis. The uniquely numbered leg bands will allow us to better understand how individuals navigate and disperse through our urban landscape as it changes over time.

​Screech-owl fledglings usually leave the nest at about thirty days, so they should soon be out and about. Perhaps you’ll catch sight of one perched on a branch in the Park or silhouetted against the sky. However, for the sake of letting them carry on with their purpose undisturbed, I suggest forgetting they’re even there while enjoying time in such an accessible and unique urban resource. Doing so makes a serendipitous encounter with a neighboring owl even more rewarding.