Artificial roosts for tree‐roosting bats in northern Arizona

Abstract

Bats use large (69 cm mean diameter) ponderosa pine (Pinus ponderosa) snags for maternity roosts in northern Arizona. Anthropogenic causes have altered forest structure, decreasing density of large snags. To examine use of artificial roosts for bats in these forests, we selected 26 sites and 2 treatments (clustered, single) using 1 type of roost (resin or wood) per site. At each site, we installed 4 roosts on ponderosa pine trees with a cluster of 3 roosts (south-, east-, or west-facing; <20 m apart) and a single roost (south-facing) 250-350 m away. We checked roosts every 2 weeks for use (guano or bats) and monitored internal temperatures every 2 hours from May through September in 2009 and 2010. Bats used 52% of roosts (19 roosts in 2009, 49 in 2010) at least once and colonized resin roosts sooner than wood roosts. Sites with clustered resin roosts were used more than single roosts. Bats used south-and east-facing resin roosts more and these had warmer average temperatures than west-facing roosts. We captured 47 bats of 5 species using artificial roosts. We only captured male bats from roosts in 2009, juveniles and females were also captured in 2010 but no maternity roosts were documented. We recommend that resin roosts placed in clusters on live trees be used to supplement natural roosts in ponderosa pine forests. Because use increased with time we suspect artificial roosts may be used for several years before establishment of maternity colonies. Artificial roosts require annual maintenance (e.g., waterproofing) to maintain function and can be expensive to install and maintain. ß

Thinking outside the box: A review of artificial roosts for bats

“…Boxes varied in dimensions, entrance locations, number of compartments, and thickness of wood. Several other types of roosts were designed to mimic exfoliating bark such as cedar shingles (singles and strings) strung around trees, tarpaper and plastic plus tarpaper (Whitaker et al ), and resin (Siders , Chambers et al , Mering and Chambers , Wilhelm ). The remaining roosts were constructed to mimic other natural roost sites such as foliage, hollow trees, or caves.…”

“…Ten studies provided roosts facing different directions, but placed only one roost per tree. Mering and Chambers () found that east‐ and south‐facing roosts were used more and had warmer average temperatures than west‐facing roosts. Flaquer et al () had higher occupancy in east‐facing compared with west‐facing roosts on buildings.…”

“…References: 1, Storer (); 2, Golding (); 3, Boyd and Stebbings (); 4, Neilson and Fenton (); 5, Freer et al (); 6, Park et al (); 7, Keeley and Tuttle (); 8, Benzal (); 9, Gerell and Lundberg (); 10, Irvine and Bender (); 11, Arnett and Hayes (); 12, Brittingham and Williams (); 13, Ward (); 14, Kasprzyk and Ruczynski (); 15, Kerth et al (); 16, Chambers et al (); 17, Smith and Agnew (); 18, Kiser and Kiser (); 19, White (); 20, Lourenço and Palmeirim (); 21, Bender (); 22, Ciechanowski (); 23, Ritzi et al (); 24, Flaquer et al (); 25, Long et al (); 26, Rhodes (); 27, Whitaker et al (); 28, Baranauskas (); 29, Bartonička and Řehák (); 30, Horncastle et al (); 31, Horncastle et al (); 32, Kelm et al (); 33, Matsuoka (); 34, Baranauskas (); 35, Lesinski et al (); 36, Reid et al (); 37, Baranauskas (); 38, Meddings et al (); 39, Mering and Chambers (); 40, Shek et al (); 41, Wilhelm ().…”

“…In some cases, this was because the focus was not directly related to replacing lost roosts but rather to help move bat colonies away from people (Brittingham and Williams , Nagorsen ), test management treatments (Horncastle et al , ), or easily study colonies (Bartonička and Řehák ). Often natural roost density was not measured directly but suggested to be low because human actions had resulted in the loss of forest structure (e.g., Altringham , Smith and Agnew , Flaquer et al , Mering and Chambers ). Because this assumption was rarely tested, and if conservation funds are limited, it might be preferable to first determine whether natural roosts for target species are lacking, before placing artificial roosts.…”

“…For example, the lesser horseshoe bat ( Rhinolophus hipposideros ) did not use bat boxes (Mitchell‐Jones ) although it used a building constructed for horseshoe bats (Freer et al ). The fact that bats were more likely to colonize artificial roosts that mimicked natural ones may explain high occupancy rates of resin and plywood roosts that imitated ponderosa pine bark ( Pinus ponderosa; Siders , Chambers et al , Mering and Chambers ).…”