Christiana Manville of the Nevada Fish and Wildlife Office (front row, second from left) joins volunteer monitors during a burrowing owl monitoring training in late February 2008. (photo: Maureen Kammerer, by permission)

Volunteer Craig Felts and his wife monitor an owl nest in the City of North Las Vegas during the study. (photo: Maureen Kammerer, by permission)

Young burrowing owls first emerge from nest at around 12 days old. (photo: Maureen Kammerer, by permission)

by Christiana Manville, Nevada FWO
In 2008, the Nevada Fish and Wildlife Office in Las Vegas partnered with the Red Rock Audubon Society to conduct an urban burrowing owl monitoring study.  This project used volunteers to document and map known burrows, survey for new burrows, and monitor nest burrows.  Thirty-five volunteers monitored 34 nest burrows throughout the breeding season in the Las Vegas Valley.  Monitoring consisted of observing the owls for half an hour once a week around sunrise or sunset and filling out a data sheet to record the number of owls observed, the age of the owls, and their behaviors.  Volunteers included employees of local governments, residents who have been watching owls for years in their neighborhoods, college students, and members of Red Rock Audubon Society. 

The project mapped 393 burrows used by burrowing owls. Burrow locations were shared with landowners that were developing several sites where owls occurred.  Landowners avoided take of owls, and in two locations are mitigating for the loss of natural burrows by installing artificial burrows. 

The majority of the nest monitored occurred in the north end of the Valley with the largest numbers of nests being monitored at the following locations: Knells Air Force Base along Range Wash (6 nests), Floyd Lamb Park (5 nests), adjacent to Gilcrease Orchard (5 nests), and adjacent to RC Farms (4 nests).  Owls mostly nested in animal burrows but some nested in other structures, including a hole under a sidewalk, and under an old box spring mattress.

Many monitors observed their owls mating and males bring females food during incubation.  Young were first seen between May 22 and June 20 and were estimated to be between 11 and 23 days old when they were first seen.  We learned that adult owls become much more sensitive to people once young have emerged from the nest.  Observation distances had to be increased, in some cases up to 400 feet away, to avoid alarming the adults.

Approximately 79 percent of nests produced young that survived to the intensive monitoring period when the juveniles were 21 to 28 days old and most easily observed (79 percent of 33 nests).  These nests are considered successful nests.  Fewer nests produced young that survived to the fledgling stage when the young are at least 44 days old (68% of 31 nests).   Unfortunately due to incomplete monitoring data or improper monitoring methods no all the data for each burrow could be analyzed.

Of the nests successful to the intensive monitoring period, there were on average 3.1 young per nest (n=23, ±1.4).  The number of young ranged from 1 to 6.  Of the nests successful to fledgling stage, there were on average 2.7 young per nest (n=14, ± 1.2).  The number of young also ranged from 1 to 6.  At two nests predation of young and possibly adults were documented.  One nest was located in Floyd Lamb and the other at near RC farms.  Remains of the owls were observed near the burrow entrances. 

Owls were observed bringing the following food items to their nests:  mice, snakes, grasshoppers and other insects, scorpions, lizards, and antelope ground squirrels.  Threats to nests that volunteers observed include children on motorized and non-motorized bikes, off-road-vehicles, placement of large objects in borrow entrances, domestic dogs, cats, and weeds at burrow entrances.

Volunteers enjoyed their experiences.  Volunteer John Baileki described his experience this way, "Yes, it was an effort to stake out and watch; and 4 dollar gas didn't help, but the reward was worth it.  I have a new and deeper understanding of the burrowing owl and its fight for survival.  I can only wish that others could take advantage of a similar opportunity".  Volunteer Billy Chapman describes the first time he saw young owls at his nest burrow, "A few minutes after I had completed my official thirty minutes of monitoring, I took one more look through my scope.  Suddenly, a young owl exited the burrow.  Then, another one appeared!  Shortly after, a third baby owl came out of the burrow.  I stood there silently grinning from ear to ear, but I felt like jumping up and down, shouting, they're here."

The results of this study will be used to assist the Service with burrowing owl conservation in southern Nevada.