Male Roosts Research Articles

Roost Use and Movements of Northern Long-Eared Bats in a Southeast Nebraska Agricultural Landscape

Bats are important bio-indicators of ecosystem health and provide a number of ecosystem services. White-nose Syndrome and habitat loss have led to the decline of many bat species in eastern North America, including the federally threatened northern long-eared bat, Myotis septentrionalis. White-nose Syndrome was only recently found in Nebraska, which lies on the western extent of this species geographic range. To better understand how this forest-dependent species persists in an agriculturally dominated landscape amid a growing number of pressures, we investigated the roosting habits of this bat at the Homestead National Monument of America, located in southeast Nebraska. We mist-netted bats on eight nights in 2019 (16 August–26 August) and caught 55 bats across five species, including five juvenile northern long-eared bats. We located five unique roosts between two juvenile radio-tracked bats; most of the female roosts were in anthropogenic structures and tree cavities within 0.23 km of capture, while most of the male roosts were in snags and tree cavities as far as 2.73 km from the capture site. Fence cavities were also used by other undocumented northern long-eared bats. We recorded three radio-tagged bats that commuted between roosting sites and capture sites within hours after sunset. Our results provide evidence that at the distributional edge for this species, wooded areas, riparian zones, and human-built structures in an intensively managed agricultural landscape are used by this imperiled species.

Mismatch between diurnal home ranges and roosting areas in the Wood Thrush (Hylocichla mustelina): Possible role of habitat and breeding stage

ABSTRACT The behavior of roosting birds has received little attention from ornithologists, despite its importance for understanding the complete avian circadian cycle. We examined the spatial arrangement of roosts in relation to diurnal home ranges for the declining Wood Thrush (Hylocichla mustelina) on its breeding grounds in coastal Virginia, USA. To our knowledge, this is the first broad description of roosting ecology for a North American migratory passerine during the breeding season. The primary objective of this study was to determine whether roost sites and diurnal use areas overlapped. Secondly, using LiDAR, we tested the hypothesis that birds roosted at sites with higher local vegetation density than random points. Lastly, we explored the effect of nest status on the roosting patterns of pairs. We tracked 37 radio-tagged males to construct 95% kernel diurnal home ranges. In 10 home ranges we also tagged the female mates. Both sexes were tracked at night to roosting locations. Of 74 male roosts, ...

Roost Habitat of Mexican Spotted Owls (Strix occidentalis lucida) in the Canyonlands of Utah

ABSTRACT In large portions of their geographic range, Mexican Spotted Owls (Strix occidentalis lucida) roost in forest-dominated environments, but in some areas the owls use relatively arid rocky canyonlands. We measured habitat characteristics at 133 male roosts (n = 20 males) during 1992–95, and 56 female roosts (n = 13 females) during 1994–95 in canyon environments of southern Utah. Across all years, 44% of Mexican Spotted Owls’ roosts were located in small stands of mixed-conifer forest, 30% in desert scrub vegetation, 16% in pinyon-juniper woodlands, and 10% of roosts were in riparian habitat. Roost sites were located in canyons composed of cliff-forming geologic formations. The width of canyons measured at roosts averaged 68.6 m (8.2 SE), and ranged from 1–500 m. The mean height of cliffs at roost sites was 77 m (10.9 SE) and ranged from 6–411 m. Roosts were located at caves and ledges (46% of all roosts) or in various tree species (54%). Roost height above ground averaged 9.5 m overall (1.1 SE), wi...

Population structure of Daubenton’s bats is responding to microclimate of anthropogenic roosts

Roost microclimate plays an important role in the survival, growth and reproduction in microbats. Entering torpor is one of the main energy saving mechanisms commonly used by microbats. The use of torpor is affected by roost microclimate and seasonally differs between the two sexes in relation to their reproductive condition. Consequently, thermal properties of male and female roosts should differ. To test this hypothesis, we compared temperature parameters of two anthropogenic day roosts of Daubenton’s bats with a different structure of the population inhabiting them. In accordance with our predictions, the roost occupied by a male-dominated colony was colder and more fluctuant than the maternity roost with a female-dominated population. However, using of the two roosts changed during the season in response to changing energetic demands of the two sexes. While males were almost absent in the warmer maternity roost during pregnancy and lactation, they appeared in this roost during the post-lactation when mating starts. In contrast, females did not use the colder (male) roost until the time of weaning of juveniles, i.e., the time when their thermoregulatory needs change and they may benefit from using colder roost. Our study provides the evidence that the same roost may be used by individuals of different sex and reproductive state in different periods of the year. Generalizations about roost selection without knowledge of temporal variation in roost use and microclimatic conditions should be taken with caution. Anthropogenic roosts may be advantageous to Daubenton’s bats as these can provide a variety of suitable microclimates and/or more space for roosting than tree cavities.

Mating System of a Migratory Bat, Nathusius' Pipistrelle (Pipistrellus nathusii): Different Male Strategies*

The mating system of European bats is often reported as ‘resource-defence polygyny’ where the resource is a male roost and its adjacent territory. With a large amount of field data we tested predictions of that model on the spatial dispersal of males in a resident population of a migratory species, Pipistrellus nathusii, well known for its complex vocal advertising by males during the mating season. The study was conducted in southern Bohemia throughout nine seasons (1999–2007) and revealed that (i) pronounced aggregations of male roosts and vocalization sites were affected by the vicinity of the breeding colony, and (ii) dyadic or triadic aggregations were observed in 65% of resident males that shared a common vocalization site. Dyadic or triadic groups were often quite stable over time (for up to seven successive years). No direct agonistic behaviour was observed between group members in contrast to regularly observed synchronization in their activity patterns and advertisement vocalizations. The busy vocalization sites were also visited by alien males that also produced advertisement vocalization and by non-vocalizing males that may have acted as sneaks. All these phenomena suggest considerable diversity in male strategies, suggesting that the mating system does not correspond entirely to ‘resource-defence polygyny’ nor can it be regarded as a lek mating system to which it corresponds in other characteristics (e.g., aggregations of males and the essential role of female choice). We expect that the broad diversity in mating tactics that characterises the species under study may also reveal features relevant to the mating systems of other temperate bats.

Evening Bat Summer Roost‐Site Selection on a Managed Pine Landscape

ABSTRACT Creation and maintenance of forested corridors to increase landscape heterogeneity has been practiced for decades but is a new concept in intensively managed southern pine (Pinus spp.) forests. Additionally, more information is needed on bat ecology within such forest systems. Therefore, we examined summer roost‐site selection by evening bats (Nycticeius humeralis) in an intensively managed landscape with forested corridors in southeastern South Carolina, USA, 2003–2006. We radiotracked 53 (26 M, 27 F) adult evening bats to 75 (31 M, 44 F) diurnal roosts. We modeled landscape‐level roost‐site selection with logistic regression and evaluated models using Akaike's Information Criterion for small samples. Model selection results indicated that mature (≥40 yr) mixed pine‐hardwood stands were important roost sites for male and lactating female evening bats. Upland forested corridors, comprised of mature pine or mixed pine‐hardwoods, were important roosting habitats for males and, to a lesser extent, lactating females. Male roosts were farther from open stands and lactating female roosts were farther from mid‐rotation stands than randomly selected structures. Our results suggest roost structures (i.e., large trees and snags) in mature forests are important habitat components for evening bats. We recommend maintaining older (>40 yr old) stand conditions in the form of forest stands or corridors across managed landscapes to provide roosting habitat. Furthermore, our results suggest that an understanding of sex‐specific roost‐site selection is critical for developing comprehensive guidelines for creating and maintaining habitat features beneficial to forest bats.

Roost selection by Big Brown Bats in Forests of Arkansas: Importance of Pine Snags and Open Forest Habitats to Males

Although Eptesicus fuscus (Big Brown Bat) has been widely studied, information on tree-roosting in forests by males is rare, and little information is available on tree roosting in the southeastern United States. Our objectives were to characterize diurnal summer roosts, primarily for male Big Brown Bats, and to determine relationships between forest structure and roost selection. We quantified 25 male roosts located via radiotelemetry, and describe an additional 9 maternity roosts for females. All roosts for both sexes were in Pinus echinata (Shortleaf Pine) snags, and 82% of roost snags were 15–25 cm diameter at breast height (dbh). Most (94%) roosts for both sexes were under loose bark. A logistic regression model differentiating male roost sites from random locations indicated males were more likely to roost in recently thinned, open-forest conditions (less canopy cover, more cut stumps, and fewer under-story stems) that contained abundant overstory pines ≥25 cm dbh and abundant snags. Males roosted primarily (84%) in stands that had recently undergone partial harvesting. Maintaining a supply of pine snags ≥15 cm dbh in relatively open forest habitats, including areas undergoing partial harvest, would provide roosting habitat for male Big Brown Bats in the Ouachita Mountains.

Sex-specific roost selection by adult red bats in a diverse forested landscape

The eastern red bat ( Lasiurus borealis) is a common, widespread species that occurs throughout eastern North America; however, information on potential differences in roost selection between sexes is limited. We studied summer diurnal roosting of adult red bats in a diverse forested landscape to: (1) characterize roosts of adult males and females, (2) determine habitat relationships for both sexes, and (3) compare roost selection between the sexes. We radiotracked 21 male and 20 female red bats to 142 roost locations and quantified roost characteristics. Both sexes roosted mostly in overstory hardwoods (82% of male and 81% of female roosts), but males occasionally (8% of roosts) roosted in sapling (<5 cm diameter at breast height; dbh) whereas females did not. Females roosted at greater heights than males but, mean diameter and height of roost trees ≥5 cm dbh did not differ between sexes; roosts trees used by both sexes were greater in diameter and height than random trees. We found no difference between sexes in tree species used for roosting; both sexes preferred to roost in white oaks ( Quercus alba) and hickories ( Carya spp.) but avoided Pines ( Pinus spp.). Sex-specific habitat models created using an information-theoretic approach indicated males were more likely to roosts at sites with more midstory (5–10 cm dbh) and small overstory (10–25 cm dbh) hardwoods, taller hardwoods, shorter pines, and further from the nearest tree than random. Females were more likely to roost at sites with more midstory hardwoods, fewer small overstory pines (10–25 cm dbh), and fewer understory (<5 cm dbh) woody stems than random. Comparisons of mean habitat parameters surrounding roost sites indicated only distance to nearest tree differed ( P < 0.05) between sexes; females roosted further from the nearest tree than males. Ninety-five percent of male roosts and 92% of female roosts were in stands dominated by mature (≥50 years old) trees, and 45% of male roosts and 40% of female roosts were in stands that had been partially harvested 1–5 years earlier but retained mature overstory hardwoods. Retaining minimum basal areas of 1.1–2.3 m 2/ha of overstory hardwoods and retaining unharvested buffers along stream drains in harvested areas would likely provide adequate roosting habitat for both sexes of red bats in managed landscapes during summer.

Roost selection by male and female northern long-eared bats in a pine-dominated landscape

We radiotracked 17 male northern long-eared bats ( Myotis septentrionalis) to 43-day roosts and 23 females to 49-day roosts in the Ouachita Mountains of central Arkansas during summers 2000–2005. We compared characteristics of roost trees between males and females, and compared characteristics of sites surrounding roosts with random locations for each sex. Roosts were located in cavities, crevices, and under loose bark, primarily in snags; 85% of male and 95% of female roosts were in snags. Shortleaf pine ( Pinus echinata) was the most utilized tree species (71% of roosts) and both sexes preferred ( P < 0.05) pine snags over hardwood snags. Most (80%) snag roosts were in snags 10–24.9 cm dbh, but females roosted in snags of greater diameter than males and males tended to roost more in small (<10 cm dbh) hardwoods than females. Female roost sites were more likely to have fewer large (≥25 cm dbh) hardwoods, fewer midstory pines 5–9.9 cm dbh, fewer small (<10 cm dbh) hardwood snags, more overstory pines ≥25 cm dbh, and more pine snags <10 cm dbh than random sites. Most (55%) female roosts were located in pine-dominated stands that had undergone partial harvesting and midstory removal. Males were more likely to select sites with abundant large (≥25 cm dbh) overstory pines, fewer small overstory pines (10–24.9 cm dbh), and more large pine snags ≥10 cm dbh than random. More male roosts (42%) were in unharvested stands than female roosts (24%), and females roosted at sites with fewer midstory trees than males. Our results demonstrate the importance of pine snags as roosting habitat for northern long-eared bats and the importance to females of snags located in relatively open forests in the Ouachita Mountains during summer.

Species-specificity and individual variation in the song of male Nathusius’ pipistrelles (Pipistrellus nathusii)

Sequences of the advertisement calls produced by male Nathusius’ pipistrelles (Pipistrellus nathusii) during the autumn mating period were recorded from individuals at two separate sites in Antrim, Northern Ireland, in August 2004. Several male roosts were found at these sites in close proximity to a single maternity roost, each containing approximately 200 adult females and their young. Analysis of measured parameters of four identified call types revealed that there were significant differences in call structure between sites and between individuals. Playback experiments, performed outside the adult female and juvenile roost sites, comprised of experimental advertisement call sequences of P. nathusii, Pipistrellus pygmaeus and Pipistrellus pipistrellus and control sound recorded without bats present (silence). Response was measured by simultaneously recording ultrasound during playbacks and counting the number of echolocation pulses identified as those of P. nathusii above a predetermined amplitude threshold. Significantly greater numbers of P. nathusii echolocation pulses were recorded during playback of male P. nathusii advertisement calls than during playback of congeners’ advertisement calls and control sound. The number of echolocation pulses recorded was similar during playback of P. pipistrellus and P. pygmaeus advertisement calls and silence. We suggest that, due to call complexity, male P. nathusii advertisement calls should be classified as ‘song’. Species-specificity and individual variation suggests that the songs of male P. nathusii have the potential to play a role in mate attraction and mate assessment.

Resource distribution and social structure in harem-forming Old World fruit bats: variations on a polygynous theme

The prediction that the spatial dispersion of resources that are important to females should dictate female dispersion and male mating tactics has not been previously tested in harem-forming bats. We investigated the relation between the estimated spatial distribution of available roosts, female group size, male roost fidelity and the strength of social associations in two species of harem-forming fruit bats in the genus Cynopterus. We evaluated the daily movements of individuals and groups among roosts using radiotelemetry and roost censuses at two sites in northern peninsular Malaysia. We found a high correspondence between the distribution of roost sites, female group size and male behaviour, supporting the prediction that clumped resources would promote female aggregation and high roost fidelity in males. However, there were significant interspecific differences in the strength of male–female associations, which suggested that, where roosts are abundant and similar in quality, regardless of their spatial distribution, the potential for males to monopolize mates depends on whether females move among roosts with, or independently of, males. We propose that interspecific differences in female behaviour may be related to the costs of moving between clumped versus randomly dispersed males.

The reproductive success of the parasitic bat fly Basilia nana (Diptera: Nycteribiidae) is affected by the low roost fidelity of its host, the Bechstein’s bat (Myotis bechsteinii)

We studied the reproductive ecology of the bat fly Basilia nana on free-ranging colonial female and solitary male Bechstein's bats (Myotis bechsteinii) during one reproductive season. The reproduction of B. nana took place from April to September, and the production of puparia in bat roosts was high. The metamorphosis of the flies took a minimum of 30 days, and at least 86% of the puparia metamorphosed successfully. However, only about 30% of flies from puparia deposited in female roosts and 57% of flies from puparia deposited in male roosts emerged in the presence of Bechstein's bats and were thus able to survive. The significantly higher emergence success of bat flies in male roosts was caused by the higher roost fidelity of the solitary males compared with the social females. Our results indicate that bats can control the reproductive success of bat flies by switching and selecting roosts.

Sex‐related differences in roost‐site selection by Daubenton's batsMyotis daubentoniiduring the nursery period

1 We investigated sex-related differences in roost-site selection by Daubenton's bats Myotis daubentonii in their summer habitat in central Germany. We studied whether the location of and landscape structure around nine nursery roosts and seven male-only roosts differed during the nursery period (15 May−31 July). Roosts were located by radio-tracking, and animal numbers and group composition were obtained by trapping and counting at roosts. Landscape structure was evaluated by a GIS-based habitat analysis. 2 Marked variation in animal numbers was observed both in nursery roosts (range: 6–144 individuals) and male roosts (range: 1–51 individuals). The surroundings of nursery and male roosts varied significantly in the proportion of areas belonging to different landscape elements. The areas covered by ponds, lakes and rivers, as well as the area covered by coppices were larger in the surroundings of nursery roosts. Moreover, nursery roosts lay closer to a river and at lower altitudes than male roosts. Male Daubenton's bats used more distant foraging sites than gravid or lactating females. 3 The differences in roost-site location between the two sexes are suggestive of intraspecific competition for access to productive foraging areas in the surroundings of the summer roosts, with females being dominant over males. We assume that breeding females defend climatically favourable areas with good food supply in order to increase the survival of their offspring.

Male roosting habits and mating behaviour of Myotis myotis

Attic‐dwelling male Myotis myotis use different roost sites, but prefer one (or a few) of them and visit others sporadically. Roost‐site preference can change, especially during the mating season. The males use their roost sites over years. Mean occupancy of all roost sites shows a maximum during the mating season. Females of different nursery colonies meet at male roost sites as far as 12 km from their colonies. They stay, on average, four days with one male, may join several males during one mating season and may visit their mating sites over years. Males appear to show no special behaviour to attract females but extend the time they are present at the roost site during the mating season. Each male is visited by about seven adult mates, on average. Differences in reproductive success are indicated by the times males were joined by females and by the numbers of mates and copulations. Two typical mating postures, copulation and five different social calls are described. Since females of different colonies meet at the male roost sites, the mating system of Myotis myotis may favour genetic exchange between colonies.

A study of the life history or Blue Magpie

1. Roosting behavior of the Blue Magpie Cyanopica cyana was studied during March 1962 and April 1964 in Nagano district, Honshiu.2. Apple orchards and garden trees were used as roosts and factors such as, kind and height of trees, foliage cover, nearby traffic and snow, were analysed.3. The roosts were seasonally changed according to the annual flocking cycle and roost conditions.4. Five categories of flock roosting could be classified into: male roost (during incubation period), family roost, compound family roost, small area roost (autumn to winter) and large area roost (winter).5. These consisted of three types: breeding season roosts, roosts within a home range and roosts outside home range (winter).6. Factors influencing the roosting behavior: light intensity and food condition, were considered.7. The evening (entering) and morning (leaving) behavior at roosts in different roost types and seasons were described.