Roost Characteristics and Clustering Behavior of Western Red Bats (Lasiurus Blossevillii) in Southwestern New Mexico

Western North American Naturalist Volume 78 Number 2 Article 7 7-19-2018 Roost characteristics and clustering behavior of western red bats (Lasiurus blossevillii) in southwestern New Mexico Brett R. Andersen Biology Department, University of Nebraska at Kearney, Kearney, NE, [email protected] Keith Geluso Biology Department, University of Nebraska at Kearney, Kearney, NE, [email protected] Follow this and additional works at: https://scholarsarchive.byu.edu/wnan Recommended Citation Andersen, Brett R. and Geluso, Keith (2018) "Roost characteristics and clustering behavior of western red bats (Lasiurus blossevillii) in southwestern New Mexico," Western North American Naturalist: Vol. 78 : No. 2 , Article 7. Available at: https://scholarsarchive.byu.edu/wnan/vol78/iss2/7 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Western North American Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Western North American Naturalist 78(2), © 2018, pp. 174–183 Roost characteristics and clustering behavior of western red bats (Lasiurus blossevillii) in southwestern New Mexico BRETT R. ANDERSEN1,* AND KEITH GELUSO1 1Biology Department, University of Nebraska at Kearney, Kearney, NE 68849 ABSTRACT.—The western red bat (Lasiurus blossevillii) is a foliage-roosting species of riparian habitats in arid regions of the southwestern United States. Only limited published anecdotal observations exist for roost sites used by this species. Western red bats were split taxonomically from the eastern red bat (Lasiurus borealis) in 1988, but summaries of roosting behaviors for western red bats still appear to stem from former associations with the commonly studied eastern red bat. Our study represents the first comprehensive research on the roosting ecology of western red bats. We radio-tracked 14 adult bats to 19 different day roosts along the Mimbres River of southwestern New Mexico. While we documented that western red bats had an affinity for densely foliated trees (79%), we did not detect any selection for tree species or size. At our study site, western red bats roosted in cottonwoods (47%, Populus spp.), velvet ash (21%, Fraxinus velutina), box elder (16%, Acer negundo), and red mulberry (16%, Morus rubra). We also described clustering behavior, where groups of 2–3 adults roosted in direct contact with one another. Although the species was deemed to roost solitarily, the frequency of clustering behavior in our study suggests otherwise. If bats were observed in clusters, they typically exhib- ited greater roosting fidelity than solitary individuals. Because arid riparian corridors in the southwestern United States generally are considered threatened systems, protection and preservation of mechanisms that create and maintain the diversity of these riparian corridors is necessary for the survival of this uncommon and poorly understood species. RESUMEN.—El murciélago rojo del desierto (Lasiurus blossevillii) es una especie de hábitat ribereño que anida en follajes de las regiones áridas del suroeste de los Estados Unidos. Existen escasas observaciones anecdóticas de los sitios donde percha esta especie. Los murciélagos rojos del desierto se separaron taxonómicamente del murciélago colorado del este (Lasiurus borealis) en 1988. Sin embargo, la información sobre la conducta de percha de Lasiurus blossevillii aún parece surgir de antiguas asociaciones con el murciélago Lasiurus borealis. Nuestra investigación representa el primer estudio exhaustivo sobre la ecología de percha de Lasiurus blossevillii. Realizamos radio monitoreos de 14 mur- ciélagos adultos en 19 diferentes sitios de percha diurnos a lo largo del río Mimbres, al suroeste de Nuevo México. Encontramos que Lasiurus blossevillii muestra afinidad hacia los árboles frondosos (79%). No obstante, no detectamos afinidad alguna hacia una especie o tamaño de árbol en particular. En nuestro sitio de estudio, Lasiurus blossevillii percha en álamos (47%, Populus spp.), en fresnos terciopelo (21%, Fraxinus velutina), en arces negundos (16%, Acer negundo) y en moras rojas (16%, Morus rubra). También, describimos la conducta de agrupamiento, en la que grupos de 2 a 3 individuos adultos se encontraron perchando en contacto directo entre sí. Aunque, anteriormente se consideraba que esta especie perchaba solitariamente, la frecuencia de agrupamientos en nuestro estudio sugiere lo contrario. Los murciélagos observados en grupos, exhibieron mayor fidelidad al sitio de percha que los individuos solitarios. Debido a que, por lo general, las zonas ribereñas áridas del suroeste de los Estados Unidos se consideran sistemas amenazados, la protección y la preservación de los mecanismos que crean y mantienen la diversidad en estas zonas ribereñas es necesaria para la supervivencia de esta especie poco común y poco conocida. Day roosts serve a variety of important have specialized adaptations in their morphol- functions necessary for the survival of bats, ogy, behavior, and reproduction to exploit the including protection from predators, shelter foliage of trees for roosts (Carter and Menzel from adverse environmental conditions, and 2007, Altringham 2011, Harvey et al. 2011). refuge to bear and raise offspring (Humphrey Despite technological advances and increased 1975, Kunz and Lumsden 2003). Of the various interest in the roosting habits of bats since structures used as day roosts, both natural and the early 1980s (Fenton 1997), few studies artificial, trees are used by many bats. In the have investigated roost selection of lasiurids continental United States, 7 species of lasiurids (Kalcounis-Rüppell et al. 2005, Carter and *Corresponding author: [email protected] BRA orcid.org/0000-0002-7606-791X 174 ANDERSEN AND GELUSO ♦ ROOSTS OF WESTERN RED BATS 175 Menzel 2007). However, because climatic shifts, Cook 1986, Valdez et al. 1999). The western changing habitats, and human disturbances red bat is a species of greatest conservation pose threats to this specialized group of bats need in New Mexico due to a paucity of eco- (Barclay et al. 2007, Kunz et al. 2007, Arnett et logical data for this uncommon bat (NMDGF al. 2008), understanding their roosting habits 2006). Excluding an extralimital record in will be important for their conservation, as Texas (Genoways and Baker 1988), southwest- some populations are declining or are sus- ern New Mexico represents the eastern distri- pected to decline (Carter et al. 2003, Carter butional extent for western red bats in the and Menzel 2007, Arnett et al. 2008, Frick et al. United States (Adams 2003). Understanding the 2017). One such species with scant roosting roosting ecology of this species is imperative data that resides in threatened habitats is the for conservation and long-term success of western red bat (Lasiurus blossevillii). populations, as many arid riparian habitats The western red bat occurs from northern are threatened throughout the southwestern California to central Argentina (Shump and United States (Stromberg et al. 2012, Gori et Shump 1982, Cryan 2003, Gardner and Hand- al. 2014). In this study, we identified roost ley 2007). In the United States, the majority of characteristics of trees used by western red its range occurs in the arid Southwest (Adams bats along the Mimbres River in southwestern 2003). Presence of foliage-roosting western New Mexico and described clustering behavior red bats in arid ecosystems often correlates of adults at these locations. with deciduous riparian corridors (Findley et al. 1975, Adams 2003), and only a few pub- METHODS lished observations on roosts and roosting Study Area behavior are known throughout the entire dis- tribution (Grinnell 1918, Hargrave 1944, Orr From 13 May to 10 June 2015 and from 19 1950, Constantine 1959, Carter and Menzel May to 9 June 2016, we examined roost char- 2007). A limited understanding of roosting acteristics and behaviors of western red bats habits of western red bats likely stems in part along the Mimbres River, Luna County, in from their taxonomic split from eastern red southwestern New Mexico. Our netting efforts bats (Lasiurus borealis). Red bats once were were centered around 2 areas along a 3.25-km considered a single species distributed across stretch of river. At the northern netting site parts of North and South America, comprising (32.58689°N, 107.92105° W; WGS84; 1539 m 5 subspecies (Shump and Shump 1982). Two elevation), the river flowed continually during of these subspecies, an eastern clade (L. b. the study, with the river about 1 to 3 m wide borealis) and a western clade (L. b. teleotis; and 2 to 4 cm deep in most areas. This area Hall 1981, Shump and Shump 1982), occurred also contained an irrigation diversion that in the United States. Phylogenetic analyses generated a pool of water approximately 18 m demonstrated that these 2 clades represent across. Shallow pools were created by the distinct species, L. borealis, the eastern red intermittent flow of the river at the southern bat, and L. blossevillii, the western red bat netting site (32.57600°N, 107.92145°W; 1529 m (Baker et al. 1988, Morales and Bickham 1995). elevation) before the river became completely Although the eastern red bat is the most stud- subterranean. The narrow riparian corridor ied foliage-roosting bat in the United States, was dominated by large cottonwoods (Popu- few published

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