The digestibility of raw and processed soybeans by Helmeted Guineafowl,Numida meleagris

Helmeted Guineafowl, Numida meleagris, populations have declined significantly within the Midlands of KwaZulu-Natal since the early 1980s. Because guineafowl have been observed feeding on harvested soybean lands and because raw soybeans are known to contain anti-nutritional factors, research into the digestibility of raw soybeans was conducted to investigate possible localized factors in suppressing populations of these birds. A digestibility study was carried out on the apparent metabolizable energy (AME) and the amino acids of both raw and processed soybeans, as well as a number of other feed ingredients, using Helmeted Guineafowl and adult roosters, Gallus gallus, as a control. The results of the energy balance studies were similar for both the guineafowl and the roosters. Soybean, both raw and processed, was found to be comparable with the other feed ingredients in terms of the digestibility of gross energy, but the amino acid digestibility of raw soybeans was considerably lower than that of processed soybean oilcake meal. The availability of raw soybean may thus only be contributing to localized dietary constraints within guineafowl populations.     

Habitat preferences of Helmeted Guineafowl Numida meleagris in the Krugersdorp Game Reserve,Gauteng province,South Africa

Field surveys were conducted in the Krugersdorp Game Reserve, Gauteng province, South Africa, during 1978–1981 to study the habitat preferences of Helmeted Guineafowl Numida meleagris. The study area was traversed with a vehicle in the late afternoons on a set route (12 km) and at least one observation was conducted each month during the three-year period. With the aid of binoculars all guineafowl that were sighted were counted and recorded on a map. The purposes were to (1) describe the habitat preferences of guineafowl and (2) to demonstrate that weeds attracted guineafowl during winter and can be retained in modified landscapes (e.g. farms) to provide important microhabitats. The highest mean monthly density across five habitat categories throughout the year was recorded in old vegetable gardens. The old vegetable gardens of c. 35 ha attracted more than 60% of the guineafowl population from April to October, which was mainly during winter when the birds scratched actively in weedy patches.     

Actual and perceived collision risk for bird strikes at Namibian airports

At Namibia’s two major airports, Hosea Kutako International and Eros (domestic), 117 bird strike collision incidents were recorded between 2006 and 2010. A risk assessment, which included a proposed risk weighting methodology, was conducted at Hosea Kutako and Eros airports, which estimated the probability of an accident/collision as well as the consequence of such a collision. The assessment included surveys of bird occurrence frequencies as well as pilot interviews. The results of the risk assessments were compared with actual bird strike incidences for each species, frequency of occurrence of birds and pilot perceptions of species risk, in order to find whether risk assessment and pilot perception are reliable measures of potential bird strike incidence. White-backed Vulture Gyps africanus and Helmeted Guineafowl Numida meleagris were the highest risk species at both airports. They were also, after Crowned Lapwing Vanellus coronatus, the species most often observed by pilots. Bird strike records showed that Crowned Lapwing and Helmeted Guineafowl were also the most frequently struck birds at both airports. The study illustrates how combining risk assessment, pilot perception and bird strike history can benefit bird strike minimisation plans at airports through the rapid identification of priority bird species.     

The effects of agriculture and the availability of edge habitat on populations of Helmeted Guineafowl Numida meleagris and on the diversity and composition of associated bird assemblages in KwaZulu-Natal province, South Africa

We investigated the effects of agriculture and the availability of edge habitat on populations of Helmeted Guineafowl Numida meleagris and associated avian diversity and species composition in woodland and grassland biomes in the Midlands of KwaZulu-Natal province, South Africa. Study sites within woodland biome had greater species diversity than those in grassland, whereas adjacent, high-quality, protected habitat in grassland sites, enhanced diversity within this biome. Both guineafowl populations and overall avian diversity declined with increasingly intensive agriculture and disappearance of edge habitat and associated, optimally fragmented habitat mosaic. Furthermore, traditional agriculture in the form of contouring in a pesticide-free environment, resulted in extensive edge habitat that appeared to provide additional food and cover for birds. This, in turn, caused an increase in overall bird diversity, and in guineafowl populations in particular. The widespread decline in Helmeted Guineafowl populations in the Midlands that started in the 1980s, and possibly the decline in species associated with this variegated landscape, was therefore caused by the loss of the habitat mosaic to intensive, modern, monoculture, crop agriculture. Maintaining species diversity and healthy guineafowl populations within these habitats requires the persistence or re-creation of a habitat mosaic and the resulting edge habitat on a landscape scale.     

WINTER ROOSTING AND FEEDING BEHAVIOUR OF PIED WAGTAILS MOTACZLLA ALBA NEAR OXFORD, ENGLAND

This study presents data on the roosting and feeding behaviour of Pied Wagtails around Oxford, England. During the winter of 1977–78, from two to 1200 wagtails roosted in a Phragmites reed-bed. Use of this roost was greatest during mild, windless weather and the birds apparently used alternate roosts during harsh weather. Movement between roosts sometimes occurred between sunset and sunrise. Morning ‘departure group’ size, number leaving per unit time and diversity of departure directions increased with roost size. Wagtails quickly left the vicinity in the morning. In the afternoon, they joined one or more pre-roost gatherings before entering the roost for the night. Behaviour upon arrival at the roost was variable: birds might enter the reeds quickly or circle in large groups before landing. Aerial revolutions and generally ‘restless’ behaviour often accompanied increases in roost size. Wagtail feeding rates varied significantly between and within habitats. Number of wagtails feeding on the flooded Port Meadow, located 2–3 km south of the main roost, varied from about five to over 60 on different days; these numbers were not correlated with feeding rates. In contrast, the number of birds feeding at a sewage farm was nearly constant all winter. Some wagtails show high fidelity to feeding areas but others do not. Five short-term food supplementation experiments indicated that wagtails knowledgeable about a dense food source are not followed in the morning by naive birds. Results of this study are discussed in relation to the predation, physiology and information centre hypotheses that have been suggested to explain communal roosting in birds. I conclude that the communal roosting system of Pied Wagtails has physiological and anti-predator functions. Wagtails appear to choose certain roosts because of the protection that they provide from adverse climate and predation.     

NOTE ON THE SPIKE-HEEL LARKS OF THE CAPE PROVINCE

This study investigates the possibility of hybridisation between introduced domestic Helmeted Guineafowl Numida meleagris, derived from the West African subspecies N. m. galeata, and South African guineafowl, N. m. coronata. There is putative morphological evidence of such hybridisation in wild populations and it is known that domestic guineafowl do not survive well in the wild. Molecular analysis of the control region of mtDNA confirmed the occurrence of the domestic guineafowl haplotype in individuals present in wild populations from KwaZulu-Natal, but not in birds from populations from the Free State. Thus, despite the absence of the availability of bi-parentally inherited nuclear DNA marker, the presence of the domestic haplotype in individuals of both wild and intermediate phenotype (between wild and domestic birds) suggests that there is hybridisation in the wild between domestic and wild guineafowl. To avoid potential negative affects associated with outbreeding depression, we argue for careful control of releases of domestic guineafowl into the wild. This study investigates the possibility of hybridisation between introduced domestic Helmeted Guineafowl Numida meleagris, derived from the West African subspecies N. m. galeata, and South African guineafowl, N. m. coronata. There is putative morphological evidence of such hybridisation in wild populations and it is known that domestic guineafowl do not survive well in the wild. Molecular analysis of the control region of mtDNA confirmed the occurrence of the domestic guineafowl haplotype in individuals present in wild populations from KwaZulu-Natal, but not in birds from populations from the Free State. Thus, despite the absence of the availability of bi-parentally inherited nuclear DNA marker, the presence of the domestic haplotype in individuals of both wild and intermediate phenotype (between wild and domestic birds) suggests that there is hybridisation in the wild between domestic and wild guineafowl. To avoid potential negative affects associated with outbreeding depression, we argue for careful control of releases of domestic guineafowl into the wild.     

House Finch Carpodacus mexicanus roosting behaviour during the non-breeding season and possible effects of mycoplasmal conjunctivitis

We studied House Finch Carpodacus mexicanus roosting behaviour during the non-breeding season using radiotracking and direct observations in Ithaca, NY, USA. In contrast to what has been reported in the literature and in contrast to what should be expected from Newton's European studies of cardueline finches, House Finches roost in small groups (mean 3.5; maximum 11) and do not display at roost sites. Seventy-seven per cent of the birds re-used the same tree on successive observations. In winter, birds re-used the same roost tree more often than in the autumn, and birds with mycoplasmal conjunctivitis tended to move more between roost trees than did birds without conjunctivitis. A small number of radiotagged birds that roosted in the same tree were observed together in the daytime more often than by chance, suggesting the existence of social bonds between birds (some same sex) during the non-breeding season. In the autumn the birds often roosted in leafed deciduous trees and closer to their daytime feeding locations than they did in winter. In winter all birds roosted in evergreen trees. It is possible that the reliable and predictable food sources at feeding sites offered by the public might have changed House Finch roosting behaviour.     

Foraging behaviour of bird pollinators on Embothrium coccineum (Proteaceae) trees in forest fragments and pastures in southern Chile

Abstract We investigated the effects of forest patch size on the behaviour of birds feeding on the flower nectar of the proteaceous tree Embothrium coccineum J. R. et G. Forster, which is typically restricted to forest edges in agricultural landscapes in southern Chile. We quantified reproductive parameters of trees (no. inflorescences per branch, total and open flowers per inflorescence) in forest fragments varying from 1 ha (small), to 20 ha (medium) and to >150 ha (large), and in remnant trees in pastures. Visits to flowers by nectar‐feeding birds were recorded during 30‐min observation periods, spread throughout the day during two flowering seasons, November 1992 and 1993 (n = 242 periods overall). Aggressive encounters among flower visitors were recorded in 1992. We expected less visits to trees in pastures and small forest patches because abundances of Embothrium's main pollinators, the flycatcher Elaenia albiceps and the hummingbird Sephanoides sephaniodes, decreased in smaller patches. We found, however, that pollinator visiting rates were negatively correlated with forest patch area and were highest for pasture trees. This trend was largely due a decline in the number of visits by E. albiceps, the main flower visitor, in larger patches. Hummingbird visits did not change with forest patch size. Lower visitation rates to flowering trees in larger forest fragments seemed to be a consequence of territorial defence by E. albiceps and were unrelated to differences in floral display.     

Wintering forest birds roost in areas of higher sun radiation

We analyze environmental determinants of roost site selection by tree gleaning passerines wintering in a Mediterranean montane oakwood at a craggy area of high variation in altitude and hill-shading pattern. We hypothesize that in temperate latitudes of cold winter climate, birds should spend the night in areas of low altitudes, higher temperatures, and higher solar radiation in order to minimize thermoregulation costs during resting time and to improve foraging conditions just before and after roosting. We study night occupation of woodland locations by the presence of feces in 159 wooden nest boxes (i.e., under identical controlled roosting situations). We employ GIS methods to quantify solar radiation at each location surrounding the nest boxes and data loggers to measure air temperature in the field. Birds prefer to roost in forest patches with higher solar radiation, where the period of light available for foraging is extended and thermoregulation costs during daytime are minimized. They also selected woodland patches with taller trees, a pattern consistent with their foraging preferences for trunks and branches. Other environmental variables played a negligible role in determining the selection of roost sites. Here, we show, for the first time, the importance of sun radiation determining where to spend the night in wintering birds and call attention on considering the thermal space in forest management. Forest management should preserve woodland patches with taller trees more exposed to solar radiation to enhance winter habitat suitability for birds in these Mediterranean oakwoods.     

Isolated trees support lower bird taxonomic richness than trees within habitat patches but similar functional diversity

Large isolated trees are keystone structures that can help maintain biodiversity in fragmented landscapes, with evidence that open areas with isolated trees may support similar levels of taxonomic diversity to nearby patches of habitat. However, it is not clear if isolated trees can support the same diversity of ecological functions as trees in habitat patches. We compared species richness, community composition, and functional diversity of birds in trees at forest edges and isolated trees. Twenty isolated trees and ten edge trees of American muskwood (Guarea guidonia) were selected, and sampled on 11 occasions, each of 20 min, over four months. All individual birds that landed at trees were recorded using a standardized protocol. Species richness was, on average, almost twice as high at edge trees than at isolated trees. Taxonomic composition differed between edge and isolated trees, with many forest‐dependent birds restricted to edge trees, and some open‐area birds restricted to isolated trees. Overall functional diversity was similar at edge and isolated trees, but some ecological functions (e.g., frugivory) were less frequent, while others (e.g., granivory) were more frequent at isolated compared with edge trees. Isolated trees are important for supporting many ecological functions in modified areas. However, the maintenance of forest patches is essential to complement the provision of such functions in modified landscapes. Abstract in Portuguese is available with online material.     

What helps Opuntia stricta invade Kruger National Park,South Africa: Baboons or elephants?

Question : Is Opuntia stricta more frequent, and its patches larger, under trees suitable for baboon roosting? If so, does it mean that baboons are major dispersal agents and that plants established under these trees are important foci of Opuntia stricta spread? Location: Skukuza, Kruger National Park, South Africa. Method: We surveyed an area invaded by Opuntia stricta in the Skukuza region of KNP. The survey included plots under potential baboon roosting trees,plots under trees unlikely to support baboons,and paired randomly located open sites. Results: The null hypothesis ‐tree‐Opuntia spatial independence – can be rejected for Acacia nilotica, but not for Spirostachys africana. Opuntia plants are positively associated with Acacia trees suitable for baboon roosting. However, there is no significant difference between frequency of Opuntia under Acacia trees suitable and unsuitable for baboon roosting.It appears that all Acacia trees can serve as nurse trees for Opuntia. Compared to plots under Acacia trees, frequencies of old and robust Opuntia plants are significantly higher in open areas and under dead trees. Conclusions: While baboons may be responsible for long distance Opuntia dispersal (over km),their role is not detectable at a local scale.On the other hand, elephants seem to contribute substantially to the local vegetative propagation of this species. Opuntia establishment and growth are more influenced by micro‐habitat than previously thought.     

The effect of local dominance and reciprocal tolerance on feeding aggregations of ocellated antbirds

We studied ocellated antbirds (Phaenostictus mcleannani) to test the hypothesis that reciprocal tolerance between dominant individuals can favour feeding in aggregations. Mated pairs hold large non-exclusive feeding ranges, but roost and nest in a small portion of this range (‘roosting area’); adjacent roosting neighbours are unrelated. Ocellated antbirds congregate to feed on arthropods fleeing from nomadic swarms of army ants that move across the ranges of many pairs. We used playback experiments to simulate acoustic challenges, and results showed that males responded aggressively to other males only in their roosting areas. Responses to adjacent neighbours were less aggressive than to non-neighbours (i.e. the ‘dear enemy’ effect). Prey intake rates were higher when birds fed in their own roosting area or in that of adjacent neighbours compared with more distant sites. Males tolerated adjacent neighbours at swarm fronts where prey are most dense, but more distant neighbours were displaced. Despite small samples for some analyses, our results suggest that reciprocal tolerance between adjacent unrelated neighbours can ameliorate intraspecific competition within ephemeral feeding aggregations.     

Landscape Use by Hairy Woodpeckers in Managed Forests of Northwestern Washington

ABSTRACT The hairy woodpecker (Picoides villosus) is a keystone species in forest ecosystems of Washington, USA, providing nesting and roosting cavities for many species of wildlife. Therefore, management practices that promote healthy populations of this bird will help to conserve cavity-nesting communities as a whole. The objective of this study was to determine patterns in forest type and landscape use by hairy woodpeckers, and thus, provide landscape-level recommendations to forest managers. We documented the ranging patterns and habitat use of 23 hairy woodpeckers on the Olympic Peninsula using radiotelemetry and a Geographic Information System analysis. Use patterns of stand age, type, and size, as well as distance-from-edge analyses revealed that the hairy woodpecker is a relative generalist in its use of the managed forest landscape. However, certain features, such as older stands with large trees, were used more heavily by nesting pairs. Hairy woodpeckers used 61–80-year forest stands significantly (P < 0.05) more than expected relative to their availability within the birds' home ranges. We also documented significant underuse of 6–10-year and 11–20-year stands, whereas the birds used 41–60-year stands, >80-year stands, and clear-cuts (< 5 yr) equivalent to their availability. We suggest that hairy woodpeckers select older stands with larger, dying trees for foraging, but also use clear-cuts proportionally due to the residual snags, decaying trees, and remnant dead wood available. Higher use (P < 0.001) by hairy woodpeckers of small forest patches (0–5 ha) and intermediate-sized stands (5–30 ha) than large patches (>30 ha) may be a result of the older, higher-quality habitat available in small stands in the managed forest landscape. We recommend that land managers interested in maintaining healthy managed forest ecosystems with a full complement of cavity-using species in forests of western Washington and northwestern Oregon maintain a landscape mosaic with approximately 45% of the landscape in stands >40 years, and >30% of the landscape in stands >60 years.     

Trade and habitat change virtually eliminate the Grey Parrot Psittacus erithacus from Ghana

The heavily traded Grey Parrot Psittacus erithacus is believed to have undergone rapid population decline, yet there are almost no quantitative data on abundance changes over time from anywhere within its huge range. We reviewed the species’ historical abundance across Ghana, undertook targeted searches during 3‐ to 5‐day visits to 42 100‐km² cells across the country's forest zone, repeated counts at 22 parrot roosts first performed two decades ago and gauged around 900 people's perceptions of the decline and its causes. In over 150 days of fieldwork, just 32 groups (maximum group size = 12) were recorded in 10 cells. Encounter rates averaged 0.15 individuals per hour of targeted search, around 15 times lower than those recorded in the early 1990s. No active roosts were found, and only 18 individuals were recorded in three roost areas that each harboured 700–1200 birds two decades ago. Interviewees stressed the importance of very tall trees of commercially important species such as Terminalia superba and Ceiba pentandra for nesting and roosting, and believed that the felling of large trees on farmland (42% of responses) and trapping for trade (37%) were the two main causes of decline. Ghana has lost 90–99% of its Grey Parrots since 1992, a time when the population had presumably already been seriously reduced by two decades of extremely heavy trade. There is no evidence that, away from one or two localities, declines are less severe anywhere else within the West African range of P. erithacus, or across the entire range of the recently split Timneh Parrot Psittacus timneh.     

Role of exotic tree stands on the current distribution and social behaviour of Swainson's hawk, Buteo swainsoni in the Argentine Pampas

Aim The Argentine Pampas was extensively and abruptly altered by European colonization. Between 1880 and 1885 the indigenous human inhabitants were completely displaced, and native grasslands were replaced by exotic pasture plants and crops. One of the most important ecological changes in the Pampas landscape, the introduction of tall exotic tree species, has received little attention, and its effect on wildlife has never been assessed. We have made an intensive survey of habitat use of Swainson's hawk, Buteo swainsoni in its most important non‐breeding quarters, the Pampas of Argentina, aiming to characterize the sites used by hawks for communal roosting. Location Pampas grasslands, Argentina. Methods We surveyed 30,000 km of roads by car during the austral summer from 2001 to 2004, covering the main non‐breeding area occupied by Swainson's hawks. Their roost sites were located by direct observation of birds roosting in tree stands close to the roads, by surveying potential roost sites around places where groups of pre‐ and post‐roosting hawks were recorded, and by gathering information from local farmers. Results Swainson's hawks exclusively used stands of exotic tree species for roosting. Eucalyptus viminalis was present in all 34 roosts surveyed, and in 59% of them it was the only species present. The remaining exotic tree species were the Siberian elm, Ulmus pumila, pines (Pinus spp.) and cypress (Cupressus spp.). Flock sizes at roost sites were unusually high for a raptor, with an average of 658 individuals (range 8–5000 hawks, n = 27 flocks). Main conclusions The introduction of exotic trees may have resulted in the expansion of the suitable habitat for Swainson's hawks, permitting a recent colonization of the Argentine Pampas. Tree stands may have also changed the communal roosting behaviour of this raptor, by virtue of their providing new structural elements in a region that almost completely lacked trees prior to European occupation.     

Cavity selection for roosting,and roosting ecology of forest-dwelling Australian Owlet-nightjars (Aegotheles cristatus)

Abstract We compared a variety of attributes of tree cavities used for roosting by radio-tagged Australian Owlet-nightjars Aegotheles cristatus with randomly chosen prospective cavities to test which features are important for the species. Owlet-nightjars preferentially roosted in tree cavities closer to the ground, in trees with a significantly greater number of cavities and significantly closer to another tree with a cavity than expected by chance. There was also a significant interaction between cavity height and number of cavities in the tree. Tree size, decay stage and tree species were not statistically important cues used for making site choices. The requirements for Owlet-nightjars differ from those of most other Australian birds that use tree holes and also from most insectivorous bats. Telemetry data indicate that Owlet-nightjars move ～300 m between roost sites every 9 days on average. Individual birds used 2-6 different cavities during the 1–4-month period over which they were followed. The reasons for the relatively low levels of site fidelity are unknown.     

The conservation value of paddock trees for birds in a variegated landscape in southern New South Wales. 1. Species composition and site occupancy patterns

The use of paddock trees by birds was assessed in a grazinglandscape in southern New South Wales, Australia. Seventy paddock treesites were surveyed for 20 min each in the morning, and 36sites were surveyed again at midday in March 2000. During this time, thepresence and abundance of birds was recorded. Several site and landscapevariables were measured at each site. These included tree species, atree size index, a measure of the crown cover density around the site,and proximity to the nearest woodland patch. During formal surveys, 31bird species, including several woodland species, were observed usingpaddock trees. Data from bird surveys in woodland patches that wereobtained in a separate study in November 1999 were used to comparewhether there was a relationship between the abundance of a given birdspecies in woodland patches and paddock trees. Many birds commonlydetected in woodland patches were also common in paddock trees. However,some birds with special habitat requirements were absent from paddocktrees although they were common in woodland patches. Site occupancypatterns were modelled for several guilds of birds using logisticregression. Foliage-foraging birds were more likely to occupy clumps oftrees and sites with a high tree size index. Nectarivores appeared to bemore likely to be detected at sites more than 200 m fromwoodland, although this result was marginally non-significant(P = 0.08). The probability of detecting granivoreswas higher at sites with a low tree size index. Open country specieswere most likely to occupy large trees and sites that were located morethan 200 m from the nearest woodland patch. The value ofpaddock trees may have been underestimated in the past because a widevariety of bird species use paddock trees on a regular basis. Ensuringthe continued survival of paddock trees should be an important aspect offuture conservation and revegetation efforts.     

The functional roles of species in metacommunities,as revealed by metanetwork analyses of bird–plant frugivory networks

Understanding how biodiversity and interaction networks change across environmental gradients is a major challenge in ecology. We integrated metacommunity and metanetwork perspectives to test species’ functional roles in bird–plant frugivory interactions in a fragmented forest landscape in Southwest China, with consequences for seed dispersal. Availability of fruit resources both on and under trees created vertical feeding stratification for frugivorous birds. Bird–plant interactions involving birds feeding only on‐the‐tree or both on and under‐the‐tree (shared) had a higher centrality and contributed more to metanetwork organisation than interactions involving birds feeding only under‐the‐tree. Moreover, bird–plant interactions associated with large‐seeded plants disproportionately contributed to metanetwork organisation and centrality. Consequently, on‐the‐tree and shared birds contributed more to metanetwork organisation whereas under‐the‐tree birds were more involved in local processes. We would expect that species’ roles in the metanetwork will translate into different conservation values for maintaining functioning of seed‐dispersal networks.     

Roost preferences and foraging ranges of the eastern forest bat Vespadelus pumilus under two disturbance histories in northern New South Wales,Australia

Little is known about the habitat requirements of Australian bats; however, this information is needed to make better‐informed decisions when systems are disturbed. This study contrasts the roosting and foraging ecology of the eastern forest bat Vespadelus pumilus (Vespertilionidae), one of Australia’s smallest bats, between two sites of differing disturbance history on the mid‐north coast of New South Wales. Lorne Flora Reserve (182 ha) is primarily old‐growth forest surrounded by regrowth forest and eucalypt plantations, while Swans Crossing is dominated by regrowth and eucalypt plantations established on part of an old dairy farm. A total of 38 bats were tracked during the maternity and mating seasons at the two sites. Roost preferences were determined by comparing trees used as roosts with those randomly available, while foraging bats were triangulated from fixed stations at night. Bats tracked at Lorne Flora Reserve typically roosted in hollows within large, mature trees and showed a strong preference for roosting and foraging (females only) within the Reserve. Lactating females at Swans Crossing roosted in hollows of remnant rainforest trees within a gully and dead eucalypts, while males often roosted in understorey trees (such as Acacia). Dead trees were frequently used as roosts at both sites. Under both disturbance histories, the mean distance of female maternity roosts from creeks was 20 m, indicating that riparian zones provide important roosting habitat for V. pumilus. However, roosts shifted to the mid‐slope prior to winter when bats mate. Retention of mature trees in a variety of topographic locations may allow behavioural adjustments with the seasons. Bats caught in the regrowth forest also foraged there, with foraging ranges averaging just 5.3 ha (n = 10), indicating that regrowth is used by this bat for both foraging and roosting.     

Bats relocate maternity colony after the natural loss of roost trees

Understanding the ephemerality of trees used as roosts by wildlife, and the number of roost trees needed to sustain their populations, is important for forest management and wildlife conservation. Several studies indicate that roosts are limiting to bats, but few studies have monitored longevity of roost trees used by bats over several years. From 2004–2007 in Cypress Hills Interprovincial Park, Saskatchewan, Canada, several big brown bats (Eptesicus fuscus) from a maternity group roosted in cavities in trembling aspen (Populus tremuloides) trees approximately 7 km southeast away from their original known roosting area (RA1). Using a long-term data set of the roost trees used by bats in this area from 2000–2007, we evaluated whether the movement of bats to the new roosting area (RA4) corresponded with annual and cumulative losses of roost trees. We also determined whether longevity of the roosts from the time we discovered bats first using them differed between the 2 roosting areas based on Kaplan-Meier estimates. Bats began using RA4 in addition to RA1 in 2004, when the cumulative loss of roost trees in RA1 over 3 consecutive years reached 18%. Most bats exclusively roosted in RA4 in 2007, when the cumulative loss of roost trees over 6 consecutive years had reached 46% in RA1. Annual survival for roost trees, from when we first discovered bats using them, was generally lower in RA1 than in RA4. Our results suggest that the movement of bats to the new roosting area corresponded with high losses of roost trees in RA1. This provides additional evidence that to maintain high densities of suitable roost trees for bats in northern temperature forests over several decades, management plans need to recruit live and dead trees in multiple age classes and stages of decay that will be suitable for the formation of new cavities. © 2019 The Wildlife Society.