Maximum Colony Size Research Articles

Spatial structuring of coral traits along a subtropical-temperate transition zone persists despite localised signs of tropicalisation

AbstractClimate-driven species range expansions are underway with more tropically affiliated species, including Scleractinian corals, becoming increasingly abundant at higher latitudes. However, uncertainty remains on how these range shifts will affect reef-scale ecosystem processes, which will ultimately depend on the traits of the taxa that dominate these assemblages. Here, we quantified spatiotemporal patterns in the taxonomic and trait structure of coral assemblages along the subtropical-temperate coast of Western Australia (27°–34°S). Coral abundance was generally low and coral cover < 5% across our study sites. Coral assemblages shared similarities in morphological trait structures across the latitudinal gradient, mostly characterised by taxa with simple morphologies; yet subtle differences were also observed across latitudes, with high-latitude corals characterised by slower growth rates and reduced maximum colony sizes. We found a 3.4-fold increase (from 1 to 3.4 individuals m−2) in coral abundance at one heavily disturbed location, where canopy-forming seaweeds were replaced by turfing algae, a pattern that was partly driven by an increase in the relative contribution of warm affinity taxa, such as Acropora spp. We predicted these changes would be reflected in different components of functional diversity; yet, despite a localised signal of tropicalisation, we only observed subtle changes in the functional identity, richness, evenness, and divergence. The spatially invariant trait structure of coral assemblages suggests that the nature of ecosystem functions will likely remain unchanged during early stages of tropicalisation, and hence their contribution to temperate reef-scale ecological processes will depend on dominance over other benthic foundational species.

Demographic recovery of corals at a wave-exposed reef following catastrophic disturbance

Rapid recovery of coral cover following acute disturbance has been documented on many reefs. Yet measuring coverage alone can mask shifts in community and demographic structure. Here, we quantify long-term changes in population size structure for three common genera (Acropora, Pocillopora, and Stylophora) at an eastern outer reef in Palau, Micronesia, following catastrophic loss of corals due to typhoon Bopha in 2012, based on size measurements from 3648 coral colonies. Mean colony size returned to pre-disturbance levels within 4 and 6 years for Stylophora and Pocillopora, respectively. By 2020, Pocillopora colony density far exceeded pre-disturbance levels, with rapid successful recruitment following typhoon Bopha. Despite recovery of Acropora colony density by 2020, populations remained dominated by smaller colonies. We demonstrate that full demographic recovery can occur more rapidly for pocilloporids (within 6 years) compared to Acropora which had not fully recovered by 8 years post-disturbance, possibly due to fewer annual recruitment events and larger maximum colony sizes. Our results highlight the value of demographic metrics as early indicators of recovery.

Characterization of the Human Plasma Biofilm Model (hpBIOM) to Identify Potential Therapeutic Targets for Wound Management of Chronic Infections.

The treatment of chronic wounds still represents a major challenge in wound management. Recent estimates suggest that 60-80% of chronic wounds are colonized by pathogenic microorganisms, which are strongly considered to have a major inhibiting influence on the healing process. By means of an innovative biofilm model based on human plasma, the time-dependent behavior of various bacterial strains under wound-milieu-like conditions were investigated, and the growth habits of different cocci species were compared. Undescribed fusion events between colonies of MRSA as well as of Staphylococcus epidermidis were detected, which were associated with the remodeling and reorganization of the glycocalyx of the wound tissue. After reaching a maximum colony size, the spreading of individual bacteria was observed. Interestingly, the combination of different cocci species with Pseudomonas aeruginosa in the human plasma biofilm revealed partial synergistic effects in these multispecies organizations. RT-qPCR analyses gave a first impression of the relevant proteins involved in the formation and maturation of biofilms, especially the role of fibrinogen-binding proteins. Knowledge of the maturation and growth behavior of persistent biofilms investigated in a translational human biofilm model reflects a starting point for the development of novel tools for the treatment of chronic wounds.

A method for estimating colony size using queen fecundity in termites under field conditions.

Colony size in social insects is one of the most important factors in shaping their self-organized system. It affects a wide variety of traits such as foraging and defense strategies, social immune responses, the degree of polymorphism, and reproductive output. However, colony size estimation of subterranean termites in the field has been challenging, due to their extremely cryptic biology and multiple site-nesting behavior. Since natural selection favors workers that maximize the number of their siblings, the amount of egg production may reflect the number of workers in the colony. Here, we report a method for inferring colony size in the field using total egg production in each colony from a subterranean termite, Reticulitermes speratus. Our investigation of field colonies revealed that the body weight of queens reaches a peak and had the largest variance in June and July and accurately predicts the number of eggs laid by the queen per 24 h. Using laboratory-reared colonies, we found that the total egg production in each colony is proportional to the number of workers. We also estimated the colony size of 198 field colonies and found that the median and maximum colony size was 24,500 and 451,800 workers per colony. The method for inferring colony size presented here may also be applicable to termite species with a clear seasonality in egg production. The colony size estimate will contribute to understanding the life history strategies and social systems of termites.

Effect of urban habitats on colony size of ants (Hymenoptera, Formicidae)In memory of Professor A. A. Zakharov (Russian Academy of Sciences, Moscow)

Urbanized ecosystems are suitable for the habitat of only a few species of ants, due to conditions caused by human activities. Invasive species of ants have adapted to urbanized ecosystems most successfully. The study of the ant colonies sizes started in Crimea in 2013-2014. In 2019-2021 it was carried out in Ukraine (the Carpathians, Kyiv city, and Kyiv region), in Russia (Rostov-on-Don city and region, and the Urals), and in Uzbekistan (Tashkent city, and tugai forests). The study covers natural (forest, meadow, steppe), suburban (alleys and tree planting) and urban habitats (tree planting along streets and roads, botanical gardens). Our study covers 21 species of ants with trails on forage areas. Nine species were sampled for interspecific comparison of colony sizes. They were collected in at least 2 habitat types within the same geographic region. According to the activity parameter on the trails, the number of foragers and the population of the colony were calculated (using the formula of A. Zakharov). According to our calculations, the maximum colony sizes are typical for invasive species (Crematogaster subdentata, Lasius neglectus, 100-7500 thousand workers) in the urban habitats. Some native species (Dolichoderus quadripunctatus, Formica cinerea) in the urban areas have colonies with 120-350 thousand workers. These values may exceed those for ant species inhabiting natural habitats (30-250 thousand workers). High rates of colony size in the urbanized habitats can be achieved due to availability of food, nesting resources, and the absence of competing ant species. Key words: Colony size, urban ecology, invasive species, native species, Crematogaster subdentata, Lasius neglectus, Dolichoderus quadripunctatus, Formica cinerea

The effects of coral assemblage shift on reef functions in Akumal, Mexico

Caribbean coral reefs have suffered shifts in their coral assemblages, driven by local and global stressors. These shifts have affected reef functions, ecosystem processes, and services essential to human well-being. Akumal Reef, located in the northern Mexican Caribbean, generates valuable ecosystem services, mainly linked to tourism, that depend on the persistence of the reef’s physical functionality. In this study, decadal changes in coral assemblages and their effects on functional traits decline were investigated. Coral species cover was systematically monitored at 14 sites along Akumal Reef in 2001, 2010, and 2019. These data were translated to functional traits allowing the classification of coral species into life-history strategies (competitive, stress-tolerant, and more opportunistic ‘weedy’ species). Our results indicate a significant decline in stress-tolerant species cover (mostly from the genusOrbicella)in Akumal Reef between 2001 and 2010 and between 2010 and 2019, with no significant changes in coral cover of other life-history strategies. The significant shifts away from stress-tolerant species during the time studied in Akumal Reef influenced the deterioration of functional traits related to reef physical functionality, such as calcification, rugosity, average maximum colony size, and reef functional index. Currently, Akumal reef sites are dominated by non-framework-building weedy coral species and are mostly below the 10% hard cover estimated threshold for positive reef accretion in the Caribbean. Therefore, management strategies in Akumal Reef should be integrative and oriented towards reducing local stressors while actively restoring the functional structure of coral reefs and maintaining their environmental services.

Important ecosystem function, low redundancy and high vulnerability: The trifecta argument for protecting the Great Barrier Reef's tabular Acropora

AbstractIdentifying organisms that play an important role in maintaining ecosystem function is a key aspect of resilience‐based management. For Australia's Great Barrier Reef (GBR), we found that the recovery ability of shallow exposed fore‐reefs is more than 14 times higher when tabular Acropora are present. The disproportionate role that tabular Acropora play appears to be driven by a combination of traits including high recruitment, high growth rate and, importantly, large maximum colony sizes. Despite this key role, tabular Acropora are highly sensitive to most pressures. We compile evidence suggesting that if tabular corals were to decline or disappear on the GBR, the potential for reef recovery on exposed fore‐reefs would be considerably slowed. We then consider the merits of placing special emphasis on the protection of tabular Acropora within the management of the GBR. Importantly, we recognise that an analysis of costs and benefits of such recognition is vital before any change is implemented. Actions might include targeted crown‐of‐thorns starfish control, anchoring restrictions and protection for tabular corals on reefs identified as essential for their larval dispersal. In addition, targeted communications about the critical importance of these highly recognisable corals may boost community support and participation in their protection.

Sex-allocation conflict and sexual selection throughout the lifespan of eusocial colonies.

Models of sex‐allocation conflict are central to evolutionary biology but have mostly assumed static decisions, where resource allocation strategies are constant over colony lifespan. Here, we develop a model to study how the evolution of dynamic resource allocation strategies is affected by the queen‐worker conflict in annual eusocial insects. We demonstrate that the time of dispersal of sexuals affects the sex‐allocation ratio through sexual selection on males. Furthermore, our model provides three predictions that depart from established results of classic static allocation models. First, we find that the queen wins the sex‐allocation conflict, while the workers determine the maximum colony size and colony productivity. Second, male‐biased sex allocation and protandry evolve if sexuals disperse directly after eclosion. Third, when workers are more related to new queens, then the proportional investment into queens is expected to be lower, which results from the interacting effect of sexual selection (selecting for protandry) and sex‐allocation conflict (selecting for earlier switch to producing sexuals). Overall, we find that colony ontogeny crucially affects the outcome of sex‐allocation conflict because of the evolution of distinct colony growth phases, which decouples how queens and workers affect allocation decisions and can result in asymmetric control.

Mapping floral resources for honey bees in New Zealand at the catchment scale.

Honey bees require nectar and pollen from flowers: nectar for energy and pollen for growth. The demand for nectar and pollen varies during the year, with more pollen needed in spring for colony population growth and more nectar needed in summer to sustain the maximum colony size and collect surplus nectar stores for winter. Sufficient bee forage is therefore necessary to ensure a healthy bee colony. Land-use changes can reduce the availability of floral resources suitable for bees, thereby increasing the susceptibility of bees to other stressors such as disease and pesticides. In contrast, land-based management decisions to protect or plant bee forage can enhance pollen and nectar supply to bees while meeting other goals such as riparian planting for water-quality improvement. Commercial demand for honey can also put pressure on floral resources through over-crowding of hives. To help understand and manage floral resources for bees, we developed a spatial model for mapping monthly nectar and pollen production from maps of land cover. Based on monthly estimated production data we mapped potential monthly supply of nectar and pollen to a given apiary location in the landscape. This is done by summing the total production within the foraging range of the apiary while subtracting the estimated nectar converted to energy for collection. Ratios of estimated supply over theoretical hive demand may then be used to infer a potential landscape carrying capacity to sustain hives. This model framework is quantitative and spatial, utilizing estimated flight energy costs for nectar foraging. It can contribute to management decisions such as where apiaries could be placed in the landscape depending on floral resources and where nectar limited areas may be located. It can contribute to planning areas for bee protection or planting such as in riparian vegetation. This would aid managed bee health, wild pollinator protection, and honey production. We demonstrate the methods in a case study in New Zealand where there is a growing demand for mānuka (Leptospermum scoparium) honey production.

Colony-Breeding Eurasian Spoonbills in the Netherlands: Local Limits to Population Growth with Expansion into New Areas

It has been suggested that in most colony-breeding birds, food availability in the feeding areas surrounding the colonies limits, and thereby regulates, population size. However, population size is also determined by adult survival, which will additionally be influenced by circumstances outside the breeding season. Most Eurasian Spoonbills Platalea leucorodia leucorodia in The Netherlands breed on the Wadden Sea barrier islands. After 30 years of exponential growth, the breeding population in the Dutch Wadden Sea area is now levelling off towards a maximum of nearly 2000 nests. For these Spoonbills, density-dependent effects on survival by the different age-classes and in the different seasons have already been demonstrated. However, the mechanisms underlying the densitydependent survival of juveniles before and after fledging remain unclear. To examine whether these density-dependent effects reflect limitations at the colony level, we compared colony growth, chick condition and reproductive success among the Wadden Sea colonies. Population growth rates from 1988 to 2015 varied widely between the 10 existing colonies, and so did the statistically predicted maximum colony sizes. Chick condition, measured for 781 chicks in six different colonies between 2011 and 2015, was lower in stable colonies than in growing colonies, although not for the very late chicks, and reproductive success tended to be lower as well. Over the longer period of 1991 to 2011, reproductive success showed a strong negative relationship with colony size. We propose that the levelling off of colony sizes in the Wadden Sea is caused by local food limitations, and suggest further research in this direction. The continuing growth of the Dutch population is now being fuelled by exponentially increasing numbers of Spoonbills breeding in the Delta area.

Low temperature and Daphnia-associated infochemicals promote colony formation of Scenedesmus obliquus and its harvesting.

To explore the combined effects of temperature and Daphnia-associated infochemicals on colony formation of Scenedesmus obliquus to faciliate harvesting the algal biomass. A three-parameter modified Gaussian model fitted the changes of the number of cells per particle in S. obliquus induced by Daphnia culture filtrate well under any temperature. Decreases in temperature enhanced the induced-colony formation of Scenedesmus. The maximum colony size at 15-25°C was significantly larger than those at 30-35°C. An additional 1 or 2days at low temperature was needed to reach the maximum colony size, which indicates the best harvest time for algal biomass. Induced-colony formation of Scenedesmus by Daphnia culture filtrate at 15-25°C is recommended to settle algal cells. This condition facilitates harvesting the biomass.

Metabolic rate, latitude and thermal stability of roosts, but not phylogeny, affect rewarming rates of bats

Torpor is an adaptation that allows many endotherms to save energy by abandoning the energetic cost of maintaining elevated body temperatures. Although torpor reduces energy consumption, the metabolic heat production required to arouse from torpor is energetically expensive and can impact the overall cost of torpor. The rate at which rewarming occurs can impact the cost of arousal, therefore, factors influencing rewarming rates of heterothermic endotherms could have influenced the evolution of rewarming rates and overall energetic costs of arousal from torpor. Bats are a useful taxon for studies of ecological and behavioral correlates of rewarming rate because of the widespread expression of heterothermy and ecological diversity across the >1200 known species. We used a comparative analysis of 45 bat species to test the hypothesis that ecological, behavioral, and physiological factors affect rewarming rates. We used basal metabolic rate (BMR) as an index of thermogenic capacity, and local climate (i.e., latitude of geographic range), roost stability and maximum colony size as ecological and behavioral predictors of rewarming rate. After controlling for phylogeny, high BMR was associated with rapid rewarming while species that live at higher absolute latitudes and in less thermally stable roosts also rewarmed most rapidly. These patterns suggests that some bat species rely on passive rewarming and social thermoregulation to reduce costs of rewarming, while others might rely on thermogenic capacity to maintain rapid rewarming rates in order to reduce energetic costs of arousal. Our results highlight species-specific traits associated with maintaining positive energy balance in a wide range of climates, while also providing insight into possible mechanisms underlying the evolution of heterothermy in endotherms.

Decadal comparison of a diminishing coral community: a study using demographics to advance inferences of community status.

The most common coral monitoring methods estimate coral abundance as percent cover, either via in situ observations or derived from images. In recent years, growing interest and effort has focused on colony-based (demographic) data to assess the status of coral populations and communities. In this study, we relied on two separate data sets (photo-derived percent cover estimates, 2002–12, and opportunistic in situ demographic sampling, 2004 and 2012) to more fully infer decadal changes in coral communities at a small, uninhabited Caribbean island. Photo-derived percent cover documented drastic declines in coral abundance including disproportionate declines in Orbicella spp. While overall in situ estimates of total coral density were not different between years, densities of several rarer taxa were. Meandrina meandrites and Stephanocoenia intersepta increased while Leptoseris cucullata decreased significantly, changes that were not discernable from the photo-derived cover estimates. Demographic data also showed significant shifts to larger colony sizes (both increased mean colony sizes and increased negative skewness of size frequency distributions, but similar maximum colony sizes) for most taxa likely indicating reduced recruitment. Orbicella spp. differed from this general pattern, significantly shifting to smaller colony sizes due to partial mortality. Both approaches detected significant decadal changes in coral community structure at Navassa, though the demographic sampling provided better resolution of more subtle, taxon-specific changes.

Colony size and foraging range in seabirds

The reasons for variation in group size among animal species remain poorly understood. Using ‘Ashmole's halo’ hypothesis of food depletion around colonies, we predict that foraging range imposes a ceiling on the maximum colony size of seabird species. We tested this with a phylogenetic comparative study of 43 species of seabirds (28 262 colonies), and investigated the interspecific correlation between colony size and foraging ranges. Foraging range showed weak relationships with the low percentiles of colony size of species, but the strength of the association increased for larger percentiles, peaking at the maximum colony sizes. To model constraints on the functional relationship between the focal traits, we applied a quantile regression based on maximum colony size. This showed that foraging range imposes a constraint to species’ maximum colony sizes with a slope around 2. This second‐order relationship is expected from the equation of the area of a circle. Thus, our large dataset and innovative statistical approach shows that foraging range imposes a ceiling on seabird colony sizes, providing strong support to the hypothesis that food availability is an important regulator of seabird populations.

The Lilliput Effect in Colonial Organisms: Cheilostome Bryozoans at the Cretaceous–Paleogene Mass Extinction

Consistent trends towards decreasing body size in the aftermath of mass extinctions – Lilliput effects – imply a predictable response among unitary animals to these events. The occurrence of Lilliput effects has yet to be widely tested in colonial organisms, which are of particular interest as size change may potentially occur at the two hierarchical levels of the colony and the individual zooids. Bryozoans are particularly useful organisms in which to study colonial size response as they have well-defined zooids. Additionally, a number of analyses of present-day bryozoans have shown that zooid size reflects local environmental conditions, most notably seawater temperature and possibly also food supply. Following the hypothesised decline in primary productivity at the Cretaceous–Paleogene (K–Pg) mass extinction, it is predicted that bryozoan zooid size should decline in the early Paleogene, resulting in a Lilliput effect. To test this prediction, zooid size was compared across the K–Pg boundary at the assemblage level and also within 4 surviving genera. Analysis of 59 bryozoan species from assemblages on either side of the K–Pg boundary showed no significant change in zooid length. Zooid size was also measured in 98 Maastrichtian colonies and 162 Danian colonies belonging to four congeneric species. Only one of these genera showed a significant size decrease across the K–Pg boundary, the other three maintaining constant zooidal lengths, widths and areas. Additionally, the sizes of 210 Maastrichtian colonies and 163 Danian colonies did not show consistent size decrease across the K–Pg boundary in these same species, although maximum colony size did decline in three out of four genera. Furthermore, this lack of consistent size change is uniform between two distinct biogeographical regions, Denmark and the southeastern USA.

Changes in extracellular polysaccharide content and morphology of Microcystis aeruginosa at different specific growth rates

The cyanobacterium Microcystis mainly exists in colonies under natural conditions but as single cells in typical laboratory cultures. Understanding the mechanism by which single cells form small and large colonies can provide a deeper insight into the life history of Microcystis and the mechanisms of Microcystis bloom formation. In this paper, Microcystis aeruginosa cultured under varying light intensities and temperatures exhibited different specific growth rates. Correlations were found between the specific growth rate, extracellular polysaccharide (EPS) content, and morphology of M. aeruginosa. Under low light intensities and temperatures, M. aeruginosa formed small colonies (maximum colony size approximately 100 μm) and exhibited low specific growth rates. By contrast, standard culture conditions yielded single or paired cells with high specific growth rates. Moreover, the EPS content decreased dramatically with increasing specific growth rate. A significant positive linear relationship was observed between the EPS content per cell and colony size. High EPS content and colony formation were associated with low specific growth rates. The specific growth rate in laboratory cultures was higher than the in situ growth rate under natural conditions. This result may explain why Microcystis normally exists as single cells or (more rarely) as paired cells in axenic laboratory cultures after long-term cultivation, but forms colonies under natural conditions.

A mid-cretaceous origin of sociality in xylocopine bees with only two origins of true worker castes indicates severe barriers to eusociality.

The origin of sterile worker castes, resulting in eusociality, represents one of the major evolutionary transitions in the history of life. Understanding how eusociality has evolved is therefore an important issue for understanding life on earth. Here we show that in the large bee subfamily Xylocopinae, a simple form of sociality was present in the ancestral lineage and there have been at least four reversions to purely solitary nesting. The ancestral form of sociality did not involve morphological worker castes and maximum colony sizes were very small. True worker castes, entailing a life-time commitment to non-reproductive roles, have evolved only twice, and only one of these resulted in discrete queen-worker morphologies. Our results indicate extremely high barriers to the evolution of eusociality. Its origins are likely to have required very unusual life-history and ecological circumstances, rather than the amount of time that selection can operate on more simple forms of sociality.

Modeling temperature-mediated fluctuation in colony size in the fire ant, Solenopsis invicta

In the social insects, colony size is central to the survival of the queen. Two endogenous factors, worker longevity and queen's daily egg production, are known to determine maximum colony size. A third endogenous factor, duration of worker development from egg to adult, regulates the rate of colony growth. In this paper, we report findings from a simulation quantifying the effects of temperature on colony size in the fire ant, Solenopsis invicta. The monthly average temperature over a six year period for the panhandle of north Florida was interpolated to determine the effects of daily temperature on a queen's egg production, worker developmental time and worker longevity. Additional daily temperatures were simulated: 7°C higher and 7°C lower than daily temperatures for north Florida. As expected, colony size was the largest when annual temperatures were the highest across seasons, ranging from 57,000 to 187,000. Colony size at intermediate daily temperatures ranged from 14,000 to 103,000; small colonies recovered rapidly as temperatures warmed. Colony size at lower daily temperatures ranged from 14,000 to 21,000. Extended worker longevity at lower temperatures compensated for low egg production and longer developmental time. And vice versa, the queen's high rate of egg production and the shorter developmental time compensated for shorter worker longevity at high temperatures. Because the fire ant nest consists of a heat-collecting dome in which to incubate brood during cold weather, and deep chambers in which to cool workers during hot weather, colony size is likely to be higher and more stable than our simulation showed. The extended longevity of workers and queens at low temperatures, and perhaps their ability to hibernate below the permafrost, might explain the ability of ants to colonize habitats worldwide.

A single origin of large colony size in allodapine bees suggests a threshold event among 50 million years of evolutionary tinkering

Evolutionary origins of highly eusocial organization involving morphological castes have been very rare, yet these origins have often led to enormous diversification and ecological success. This suggests that once an apparently severe selective barrier to highly eusocial behaviour is overcome, major new adaptive landscapes open up. One would therefore expect a discontinuity in patterns of evolutionary change across this barrier. However, we do not know if highly eusocial organization has evolved incrementally from less complex societies, or if it has involved some kind of evolutionary leap. Our study examines this issue using colony size data from 33 allodapine bee species, with a crown age of ca. 47 Mya. Our species cover all major allodapine clades, and include Exoneurella tridentata, the only known allodapine with morphologically discrete castes. Phylogenetic analyses indicate a strong effect of phylogeny on the evolution of maximum brood size, but the effect of phylogeny on maximum colony size (number of adults) depends on whether E. tridentata is excluded or included in analyses. We found no evidence of punctuational change in maximum colony or brood sizes over the phylogeny as a whole, but colony and brood sizes in E. tridentata fall well beyond variation among the other allodapines. Colony size in E. tridentata therefore represents an evolutionary outcome that does not fit within the kinds of incremental changes found in other allodapines. We propose that E. tridentata indicates the crossing of an important threshold, and this has entailed some very unusual ecological circumstances.

Phenology and roosting habits of the Central European grey long-eared bat Plecotus austriacus (Fischer 1829)

The authors monitored five maternity colonies of Plecotus austriacus to obtain data about phenology, roosting, and emergence behaviour. The bats occupied their roosts between April and October, with maximum colony sizes in August. Roosting sites in the attic’s roof ridge and temperatures of 20–25°C were favoured. Also considering the small colony (maximum 59) and cluster sizes (maximum 13 bats), P. austriacus behaved less thermophilic than other attic-dwelling species. During low temperatures, the bats chose small crevice-like roosting sites to compensate for that; during daytime, many bats remained hidden in crevices. Emergence began approximately 30 min after sunset; the bats used multiple, preferably crevice-like openings. P. austriacus left its summer roosts comparatively late; renovation works should, therefore, not start before November. For monitoring purposes, we recommend two to three emergence countings outside the attics in early August during warm weather, alongside two attic inspections 1–2 h before emergence for offspring monitoring.