Long-Term Population Fluctuations of a Burrowing Owl Population on Kirtland Air Force Base, New Mexico, USA
Western Burrowing Owls (Athene cunicularia hypugaea; hereafter, Burrowing Owls) were once widespread residents of grasslands throughout western North America, but their range has contracted, and abundance has declined in some regions. The causes of declines and geographic variation in population trends of Burrowing Owls are unclear but may be linked to changing land use and urbanization. Burrowing Owls are often found in association with airfields and airports, and their presence at such facilities is sometimes considered to be in conflict with those operations. Documenting the long-term persistence of Burrowing Owls at active airfields can help airfield managers who face decisions regarding compatibility of owls and airfield operations. We report the results of a long-term effort to monitor Burrowing Owls on Kirtland Air Force Base in New Mexico, USA, including the rapid recovery of Burrowing Owl numbers from near-extirpation and the relationships between abundance and other demographic traits. The number of breeding pairs of Burrowing Owls increased from one pair in 2013 to 28 pairs in 2019 and 2020, and the number of fledglings produced increased from one in 2013 to 84 in 2019 and 61 in 2020. The recovery was not uniform across all areas of Kirtland Air Force Base, and some formerly occupied areas remained unoccupied. We documented dispersal outside the Air Force base boundary and that the number of breeding pairs was more strongly influenced by the number of offspring produced in the prior year than the number of owls returning from prior years, which indicated that the population is part of a larger meta-population. Our results demonstrate that the maintenance of Burrowing Owl populations is not necessarily at odds with safe airfield operations, that Burrowing Owls exhibit complex population dynamics, and can rapidly recolonize previously occupied areas if habitat and nest sites remain suitable. Fluctuaciones Poblacionales a Largo Plazo en una Población de Athene cunicularia hypugaea en la Base de la Fuerza AÉrea de Kirtland, Nuevo México, Estados Unidos
Athene cunicularia hypugaea fue alguna vez una especie residente ampliamente extendida en los pastizales a través del oeste de Norteamérica, pero su área de distribución se ha contraído y su abundancia ha disminuido en algunas regiones. Las causas de las disminuciones y la variación geográfica en las tendencias poblacionales de A. c. hypugaea son poco claras, pero pueden estar vinculadas a cambios en el uso del suelo y a la urbanización. A. c. hypugaea se encuentra usualmente asociada a aeródromos y aeropuertos, y su presencia en estos sitios entra a veces en conflicto con esas operaciones. Documentar la persistencia a largo plazo de A. c. hypugaea en aeródromos activos puede ayudar a los gestores de estos sitios que deben tomar decisiones sobre la compatibilidad de la presencia de A. c. hipogea en los aeródromos. Presentamos los resultados de un trabajo de seguimiento a largo plazo de A. c. hypugaea en la base de la Fuerza Aérea de Kirtland en Nuevo México, EEUU, incluyendo la rápida recuperación de los números de A. c. hypugaea desde estar casi extinguida y las relaciones entre su abundancia y otros rasgos demográficos. El número de parejas reproductoras de A. c. hypugaea aumentó desde una pareja en 2013 a 28 parejas en 2019 y 2020, y el número de volantones producidos aumentó de uno en 2013 a 84 en 2019 y 61 en 2020. La recuperación no fue uniforme a lo largo de todas las áreas en la Base de la Fuerza Aérea de Kirtland; algunas áreas anteriormente ocupadas permanecieron desocupadas. Documentamos dispersión fuera de los límites de la base de la fuerza aérea y que la cantidad de parejas criando estuvo más fuertemente influenciada por el número de polluelos producidos el año previo que por el número de búhos de años previos que regresaron, lo que indicó que la población es parte de una meta-población más grande. Nuestros resultados demuestran que el mantenimiento de las poblaciones de A. c. hypugaea no está necesariamente en desacuerdo con las operaciones seguras de los aeródromos, que A. c. hypugaea muestra dinámicas poblacionales complejas, y que puede recolonizar rápidamente áreas previamente ocupadas si el hábitat y los lugares de nidificación siguen siendo adecuados. [Traducción del equipo editorial]ABSTRACT
RESUMEN
Kirtland AFB, Albuquerque, NM, study site (32°03′N, 106°33′W) including the three areas that historically or currently (present study) have nesting Burrowing Owls. The majority of nests from 2014–2020 were in the flight line area, and only 0–1 breeding pair was present in the landfill grasslands during each of those years. Areas outside the colored polygons were not systematically surveyed. Source of underlying aerial image: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User Community.
Number of Burrowing Owl breeding pairs on Kirtland Air Force Base, Albuquerque, NM, 1998–2020. Data for 1998–2013 are from Arrowood et al. (2001) and Cruz-McDonnell and Wolf (2016), and data from 2014–2020 (stippled dots) are from this report.
(A) Percentage of Burrowing Owl breeding pairs that fledged >1 young, (B) average number of juveniles fledged per breeding pair, and (C) total number of juvenile Burrowing Owls fledged among Burrowing Owls on Kirtland Air Force Base, 1998–2020. Data for 1998–2013 are from Arrowood et al. (2001) and Cruz-McDonnell and Wolf (2016), and data from 2014–2020 (stippled dots) are from this report.
Relationship between number of breeding pairs of Burrowing Owls on Kirtland Air Force Base and (A) number of fledglings produced the prior year, (B) number of adults that are returnees in breeding population, and (C) the amount of precipitation (in mm) during non-monsoonal months (1 November–30 June) during the past 2 yr.
Relationship between the number of Burrowing Owl fledglings produced on Kirtland Air Force Base and the amount of precipitation (in mm) during the preceding 24 mo (i.e., June of the current year plus the 23 prior months). The relationship in a GLM was significant (F = 18.2, P <0.0001) even after controlling for the number of breeding pairs (F = 85.4, P <0.0001).
Contributor Notes
1 Email address: cconway@uidaho.edu
2 Present address: US Fish and Wildlife Service, Migratory Bird Office, PO Box 1306, Albuquerque, NM 87103 USA.
3 Present address: Warnell School of Forestry and Natural Resources, 180 East Green Street, University of Georgia, Athens, GA 30602 USA.