Shelter Resources Research Articles

Archaic-Age Architecture in Northwest Colorado

Archaic-era hunter-gatherers in the Wyoming Basin—which extends across southwest Wyoming and northwest Colorado—built domed or conical architectural features, with some exhibiting far more substantial construction than others. These structures are often archaeologically preserved as large elliptical basins, defined by charcoal-stained sediment that filled habitation footprints after abandonment. Many of these basins, or house pits, are probably residential remains, although some may have had other uses. The recent discovery of 32 house pits in Colorado’s Yampa Valley in the Sand Wash Basin has expanded the regional dataset, increasing our understanding of Archaic-era lifeways in northwestern Colorado. These discoveries further demonstrate the highly variable nature of Archaic-era structures, reflecting the adaptability of a mobile lifestyle to a specific place and time. Archaic-era use of these features in northwest Colorado occurred between about 8100 and 3755 cal B.P., demonstrating the usefulness of such shelters across a wide range of climate regimes. The greatest numbers were built between 6800 and 6000 cal B.P., coinciding with the mid-Holocene thermal maximum, when the residential settlement pattern grew more restricted, centering on water, food, and shelter resources. As the warm, arid climate ameliorated after 5500 cal B.P., use of such shelters began to decrease, demonstrating a return to higher residential mobility with greater availability of resources in the cooler, wetter climate. A comparison of Yampa Valley house pits with northern Wyoming Basin house pits indicates that Archaic-era people utilized similar structures as part of a highly adaptable mobile lifestyle for thousands of years across the Wyoming Basin.

Archaic-Age Architecture in Northwest Colorado

Archaic-era hunter-gatherers in the Wyoming Basin—which extends across southwest Wyoming and northwest Colorado—built domed or conical architectural features, with some exhibiting far more substantial construction than others. These structures are often archaeologically preserved as large elliptical basins, defined by charcoal-stained sediment that filled habitation footprints after abandonment. Many of these basins, or house pits, are probably residential remains, although some may have had other uses. The recent discovery of 32 house pits in Colorado’s Yampa Valley in the Sand Wash Basin has expanded the regional dataset, increasing our understanding of Archaic-era lifeways in northwestern Colorado. These discoveries further demonstrate the highly variable nature of Archaic-era structures, reflecting the adaptability of a mobile lifestyle to a specific place and time. Archaic-era use of these features in northwest Colorado occurred between about 8100 and 3755 cal B.P., demonstrating the usefulness of such shelters across a wide range of climate regimes. The greatest numbers were built between 6800 and 6000 cal B.P., coinciding with the mid-Holocene thermal maximum, when the residential settlement pattern grew more restricted, centering on water, food, and shelter resources. As the warm, arid climate ameliorated after 5500 cal B.P., use of such shelters began to decrease, demonstrating a return to higher residential mobility with greater availability of resources in the cooler, wetter climate. A comparison of Yampa Valley house pits with northern Wyoming Basin house pits indicates that Archaic-era people utilized similar structures as part of a highly adaptable mobile lifestyle for thousands of years across the Wyoming Basin.

Assessing Emergency Shelter Demand Using POI Data and Evacuation Simulation

Mapping the fine-scale spatial distribution of emergency shelter demand is crucial for shelter planning during disasters. To provide shelter for people within a reasonable evacuation distance under day and night disaster scenarios, we formed an approach for examining the distribution of day and night shelter demand at the plot-scale using point of interest (POI) data, and then analyzed the supply and demand status of shelters after an evacuation simulation built in Python programming language. Taking the downtown areas of Guangzhou, China as a case study, the results show that significant differences exist in the size and spatial distribution of shelter demand in daytime and nighttime, and the total demand is 7.929 million people, which is far larger than the resident population. The average evacuation time of all 16,883 routes is 12.6 min, and after the evacuation, 558 of 888 shelters exceed their capacity to varying degrees, accounting for 62.84% of the total, indicating that the shelters cannot completely receive the potential evacuees. The method proposed in this paper provides a direct quantitative basis for the number and size of new shelter resources being planned during urban renewal activities, and form a reference for land reuse and disaster prevention space organization in future urban planning.

Interventions and observations associated with survival of orphaned shelter kittens undergoing treatment for diarrhea.

The objective of this study was to identify significant associations between treatment interventions and survival of orphaned shelter kittens with diarrhea. Orphaned kittens admitted to a large open-intake municipal animal shelter and entering a volunteer foster care provider network between April 2016 and July 2017 were studied. Individual orphaned kittens for which the care provider sought examination by shelter veterinarians because of clinical signs of diarrhea were included. Treatments administered were recorded and their association with kitten survival to adoption or transfer to a rescue partner was statistically examined. A total of 1718 orphaned kittens were fostered, among which 220 kittens (12.8%) from 118 different litters were presented for evaluation of diarrhea. A total of 172 (78.2%) kittens underwent treatment for their diarrhea, among which 153 (89.0%) survived to adoption or transfer to a rescue partner and 19 (11.0%) died or were humanely euthanized. Kittens with diarrhea that were ⩾4 weeks of age were 24.8 times more likely to survive (95% confidence interval [CI] 6.8-89.8; P <0.0001). While controlling for age, kittens that received a vitamin and mineral supplement were 12.8 times more likely to survive (95% CI 3.1-52.5; P = 0.0004) than kittens with diarrhea that did not receive the supplement. Treatment with subcutaneous fluids, penicillin G, tube feeding, a probiotic containing Enterococcus faecium SF68, ponazuril or metronidazole did not statistically significantly increase the survival of kittens with diarrhea. Age ⩾4 weeks and treatment of diarrhea with a vitamin and mineral supplement favorably improves survival of orphaned kittens to adoption. Application of these findings are likely to improve the health and welfare of this population and contribute to a refinement in use of shelter resources.

PSXIII-7 Statistics and Tendencies for Dog Adoptions in the State of Washington.

Shelters often experience overcrowding, understaffing, lack of resources and economic issues that are reflected in animal stress and poor welfare. The aim of the present study was to analyze statistical tendencies to determine the length of stay (LOS) of dogs in shelters in Washington state between 2010–2017. Data on 7407 dogs from five shelters were included in the analysis. The average LOS was 21.7 days, ranging from 0–1834.0 days. Statistical differences were observed among shelters (Pwas statistically different regarding LOS (P (juveniles 15 years: 59.4 days). Breed also affected LOS (PAccording to intake type (reason why they enter the shelter), LOS was statistically different (P<0.001) (surrendered: 33.5 days, seized: 30.9 days, clinic: 0.17 days, stray: 9.9 days, transferred: 13.9 days, and unknown: 60.3 days). Likewise, outcome type (reason why the leave the shelter) was statistically different (P<0.001) (adopted: 33.5 days, clinic-out: 2.1 days, died: 27.7 days, euthanized: 2.9 days, transferred: 15.3 days, returned to owner: 6.9 days, fostered: 184.0 days and unknown outcome: 33.5 days). Finally, a significant interaction between breed, age and intake type (P<0.0001) and breed, age and outcome type (P<0.0001) was observed. In conclusion, some characteristics inherent to the dog such as breed and age influence the intake and outcome of the permanence at the shelter, therefore future strategies to target adoptions based on these characteristics will decrease the duration of stay and maximize shelter resources ultimately improving animal welfare.

Competitive and agonistic interactions between the invasive Asian shore crab and juvenile American lobster.

Invasive species can have profound ecological and evolutionary impacts on native fauna, particularly those from overlapping guilds. Intraguild predation and competition often occur simultaneously, and ontogenetic shifts in competitive strength can dictate the magnitude and direction of species interactions. The recent introduction of the Asian shore crab Hemigrapsus sanguineus to the Atlantic coast of North America has resulted in the potential for considerable intraguild interactions with juvenile American lobsters Homarus americanus, with which it now co-occupies rocky intertidal and shallow subtidal habitats. We present data from 5 yr of monthly (May-October) field sampling revealing a significant decline in lobster density as H.sanguineus density increased in the low intertidal. To investigate potential mechanisms behind this pattern, we conducted three mesocosm experiments designed to examine whether competitive interactions between H.americanus and H.sanguineus are size- or density-dependent. Larger early benthic phase lobsters (16-34mm CL) outcompeted H.sanguineus for both food and shelter resources. These lobsters fed faster and more in the presence of H.sanguineus, effectively defended shelter, were responsible for the majority of agonistic interactions, and, in multiple instances, killed and consumed H.sanguineus. Effects on sheltering and agonstic interactions by these lobsters were independent of H.sanguineus density; however, prior shelter residency increased lobster agonistic behavior towards crabs. In contrast, H.sanguineus outcompeted smaller, early benthic phase lobsters (7.2-11.2mm CL) for shelter, and these interactions were density dependent. Displacement of lobsters from shelter by crabs and cumulative agonistic interactions instigated by crabs towards lobsters scaled positively with H.sanguineus density. Given the similarity of the invasion documented here and others occurring globally, these experiments demonstrate the importance of considering how factors such as ontogeny, density-dependence, and primacy influence the outcomes of interactions between intraguild predators. Disentangling how these factors structure intraguild interactions between invasive and endemic species will both advance our fundamental understanding of community ecology and enhance efforts to conserve and manage natural resources.

Urbanization-related distribution patterns and habitat-use by the marine mesopredator, giant Pacific octopus (Enteroctopus dofleini)

Urbanization is a process that heavily alters marine and terrestrial environments, though terrestrial urban ecosystems have been studied far more intensively. Terrestrial studies suggest that urbanization can facilitate mesopredators by enhancing food and shelter resources and reducing predation pressure from apex consumers. This in turn has considerable consequences for ecological communities. We evaluated spatial distribution patterns and habitat-use of the marine mesopredator, giant Pacific octopus (Enteroctopus dofleini), relative to terrestrial urbanization intensity in Puget Sound, Washington, USA. Using field surveys and citizen-contributed data for E. dofleini, we examined whether: (1) Distribution was related to urbanization, (2) Abundance was related to the extent of benthic anthropogenic debris, and (3) Diet differed as a function of urbanization and den cover. Our results suggest that urbanization impacts may differ with depth. Mixed-effects logistic regression model estimates for the probability of occurrence increased with urbanization in deep-water (> 24 m), and decreased with urbanization in shallow water (< 18 m). Accompanying field surveys indicated that E. dofleini abundance was correlated with the number of benthic anthropogenic debris items, and that E. dofleini diets were not affected by urbanization intensity or den cover. Though E. dofleini may be synanthropic within certain urban environments, the mechanisms driving this pattern likely differ from those affecting common urban mesopredators on land, with den provisioning from man-made structures being more important than altered food resources.

Echinoid associations with coral habitats differ with taxon in the deep sea and the influence of other echinoids, depth, and fishing history on their distribution

Patterns of habitat use by animals and knowledge of the environmental factors affecting these spatial patterns are important for understanding the structure and dynamics of ecological communities. Both aspects are poorly known for deep-sea habitats. The present study investigates echinoid distributions within cold water coral (CWC) habitats on continental margins off France, Australia, and New Zealand. It further examines the influence of habitat-related variables that might help explain the observed distribution of echinoid taxa.Six echinoid taxa were examined from video and photographic transects to reveal taxon-specific distribution patterns and habitat-related influences. The Echinoidea were found in all habitats studied, but tended to aggregate in architecturally complex habitats associated with living cold-water corals. However, a taxon-specific investigation found that such associations were largely an artefact of the dominant taxa observed in a specific region. Despite the food and shelter resources offered to echinoids by matrix-forming coral habitats, not all taxa were associated with these habitats, and some had a random association with the habitats examined, while others displayed non-random associations.Echinoid distribution was correlated with several variables; the presence of other echinoids, depth, and fishing history were the most influential factors.This study indicates that image data can be a useful tool to detect trends in echinoid habitat associations. It also suggests that refinement of the methods, in particular with studies conducted at a more precise taxon and habitat scale, would facilitate better quantitative analyses of habitat associations and paint a more realistic picture of a population's ecology. Most deep-sea ecological studies to date have been conducted at a relatively coarse taxonomic and habitat resolution, and lack sufficient resolution to provide useful information for the conservation of vulnerable deep-sea habitats.

Eco-engineering of modified shorelines recovers wrack subsidies

Wrack (stranded phyto-detritus) from terrestrial and marine sources is an important source of carbon and nutrients for many intertidal habitats. In urbanised estuaries, seawalls may act as a barrier to the transport of wrack between terrestrial and marine habitats and, where they reduce the width and habitat complexity of the intertidal zone, negatively impact on wrack accumulation and retention on estuarine shorelines. We assessed differences in the accumulation of wrack between natural (sandy beach, rocky reef and rockpools) and armoured stretches of shoreline, and the efficacy of eco-engineering interventions (man-made rockpools and planted saltmarshes) in enhancing the accumulation and retention of wrack. Surveys conducted at 4 sites in Kogarah Bay, New South Wales, Australia, on 3 dates during autumn-winter 2016 revealed that on natural shorelines most wrack accumulated at the high intertidal mark. Placement of seawalls restricted wrack accumulation to the low intertidal zone, in front of the seawall. The cover of wrack was significantly less in the low intertidal zone in front of seawalls than either the high or low tidal elevations of the natural sandy beaches and rockpools. The man-made rockpools in the low tidal zone had higher cover and biomass of marine and terrestrial wrack than the low intertidal zone of the seawalls, and both these and the planted saltmarshes also supported the accumulation of wrack at the mid intertidal elevation. Experimental deployments of marked seagrass wrack revealed that the eco-engineered habitats enhanced wrack retention over a 7 day period compared with the seawalls. However, the artificial rockpools also retaining more wrack than the equivalent natural habitat. Our results suggest that the structural complexity of eco-engineered habitats can be effective at trapping and retaining wrack, with potential flow-on effects to benthic assemblages through increased food and shelter resources. When designing eco-engineering interventions for modified shorelines, scientists and managers should consider not only their impacts on biodiversity but also on key ecosystem functions.

Spatial ecology and shelter resources of a threatened desert rodent (Pseudomys australis) in refuge habitat

Our study builds on recent research on the role of drought refuges in facilitating the persistence of arid-dwelling rodents during extended dry periods by characterizing the spatial ecology and shelter use of the plains mouse, Pseudomys australis, a threatened Australian desert rodent that uses refuges. We radiotracked 18 P. australis in the western Simpson Desert, Australia, during November 2014 and May 2015, when individuals were expected to be confined to cracking clay refuge habitat. We also measured the dimensions (length, width, and perceived vertical depth) of shelter sites used by tracked individuals. A sufficient number of fixes (range = 17–64) for home range calculation by kernel density estimation was obtained for 11 of the 18 tracked individuals. Total ranges were calculated at the 90% isopleth and core areas at the 50% isopleth. The tracked animals occupied small home ranges (1.35 ± 0.56 ha) within cracking clay refuge habitat for the duration of the study. Individuals occupied distinct core areas, which were just 22.57 ± 1.54% the area of the total home ranges and centered on 1–2 frequently used burrows. Overlaps in total ranges and some burrow sharing were observed between neighboring individuals; however, core areas overlapped between only 1 pair of animals, suggesting that some group structuring may occur in P. australis refuge populations. Cracks used by tracked individuals were wider and deeper than burrows. Our study found that the short-term home ranges of the radiotracked P. australis during a dry period were situated entirely within cracking clay refuge habitat, and that shelter resources, and potentially social structuring, influence the use of space by this species.

Competitive superiority versus predation savvy: the two sides of behavioural lateralization

Many animals respond differentially to stimuli on one side of their body compared to the other. This is a reflection of being lateralized, and is a feature common in vertebrates. Given that any particular stimulus that an animal encounters, be it food, a predator or a competitor, has an equal probability of coming from either side of the body, there may be negative selection for lateralization. However, the costs of lateralization may be offset if being lateralized confers a considerable advantage in other contexts, including cognition. Here, we showed that learned responses of juvenile ambon damselfish, Pomacentrus amboinensis, to a novel predator was strongly influenced by the degree of lateralization. While both lateralized and nonlateralized fish were able to learn the predator, lateralized fish showed much stronger responses to the learned predator than nonlateralized fish. When we paired lateralized and nonlateralized fish and allowed them to interact over a shelter resource, we observed that lateralized fish were poorer competitors. They attacked less often, showed fewer displays and exhibited greater avoidance of their competitor. For many gregarious species, the expression of lateralization likely reflects a fine balance of competing selection pressures. Our work highlights the need for integrative studies.

Thermoregulatory value of cracking-clay soil shelters for small vertebrates during extreme desert conditions.

Deserts exhibit extreme climatic conditions. Small desert-dwelling vertebrates have physiological and behavioral adaptations to cope with these conditions, including the ability to seek shelter. We investigated the temperature (T) and relative humidity (RH) regulating properties of the soil cracks that characterize the extensive cracking-clay landscapes of arid Australia, and the extent of their use by 2 small marsupial species: fat-tailed and stripe-faced dunnarts (Sminthopsis crassicaudata and Sminthopsis macroura). We measured hourly (over 24-h periods) the T and RH of randomly-selected soil cracks compared to outside conditions, during 2 summers and 2 winters. We tracked 17 dunnarts (8 Sminthopsis crassicaudata and 9 Sminthopsis macroura) to quantify their use of cracks. Cracks consistently moderated microclimate, providing more stable conditions than available from non-crack points, which often displayed comparatively dramatic fluctuations in T and RH. Both dunnart species used crack shelters extensively. Cracks constitute important shelter for small animals during extreme conditions by providing a stable microclimate, which is typically cooler than outside conditions in summer and warmer in winter. Cracks likely play a fundamental sheltering role by sustaining the physiological needs of small mammal populations. Globally, cracking-clay areas are dominated by agricultural land uses, including livestock grazing. Management of these systems should focus not only on vegetation condition, but also on soil integrity, to maintain shelter resources for ground-dwelling fauna.

Hierarchical decision making: resource distribution exhibits stronger effect on crayfish dominance relationships and shelter occupation than prior social experience and resource ownership

The outcome of agonistic interactions is critical to the acquisition of vital resources. These behaviours can be influenced by several intrinsic and extrinsic factors, and multi-faceted studies are necessary for ecologically relevant studies. The aim of this study was to combine the effects of past social experience, resource ownership, and the distribution of shelter resources to examine the combination of these effects on various measures of agonism in crayfish (Orconectes rusticus). Crayfish were assigned to one of three social conditioning treatments (naïve, subordinate, dominant) and then introduced to an arena where they were assigned to a resident or intruder treatment. An intruder shelter was then positioned 20, 60 or 120 cm from the resident shelter. We found that resource distribution (shelter distance) played a larger role in influencing agonistic behaviour than did past social experience or current social status.

Behavioral decisions in sensory landscapes: crayfish use chemical signals to make habitat use choices

Animals make many ecological decisions such as foraging, mating, and avoiding predators based on the information they extract from the sensory cues in their environment. Environmental stimuli which include the information animals use for decision making can be called a sensory landscape. To investigate ecological decision making in complex sensory landscapes, we presented a crayfish with a choice of resource rich and resource poor habitats under different simulated predatory conditions within a Y-maze setting. A simulated predation event (alarm odor) was alternately placed in either the resource rich or poor habitat to observe the impact of the predation event on the habitat choice and use. Habitats consisted of multiple food resources, multiple shelter resources or combined food and shelter resources. Trials were videotaped and crayfish behavior was analyzed for time spent in each habitat under different predatory and resource conditions. Results show that crayfish avoided the location of alarm odors, regardless of resource presence. Resource preference of crayfish differed among resources depending on the alarm odor location. Female and male crayfish made different decisions based on resource type and alarm odor location. Information from the crayfish’s sensory landscape drives the decision making of crayfish. Researchers need to understand the sensory environment of an animal in order to make the most accurate prediction on an animal’s decision making and behavior. We suggest using a sensory landscape model, because organisms use the entire umwelt of stimuli to guide their decision on habitat and resource use.

The importance of underground shelter resources for reptiles in dryland landscapes: A woma python case study

AbstractFor effective fauna conservation and management, ecologists are required to identify the resources that are critical for species to survive, and consider how these are distributed across landscapes. The critical resources usually considered are food and water, but the availability of appropriate shelter resources can be a key driver of habitat suitability for terrestrial reptiles and amphibians. Reptiles are important components of dryland ecosystems, yet we have little understanding about how anthropogenic disturbances affect the availability of shelter resources and reptile survival in drylands. In this study, we used VHF radio‐tracking to assess the importance of shelter resources in determining the habitat use patterns of a Near‐Threatened reptile species, the woma (Aspidites ramsayi; Pythonidae), in modified and intact dryland landscapes of Queensland, Australia. We compared the structural and thermal attributes of locations that were used, with those that were available. Using an information‐theoretic approach, we found that the occurrence of womas was strongly associated with the presence of ground burrows, which are excellent thermal insulators. No other shelter type was capable of buffering our study species from sub‐zero temperatures during winter, although summer temperatures of &gt;40°C were buffered by hollow logs and piles of woody debris. Habitat use patterns were influenced more by the occurrence of underground shelters than by habitat type. Clearing status per se (cleared, regrowth or intact) had minimal influence on occurrence. Thermally buffered underground shelters are a vital resource for our focal species, and the availability of this shelter resource drives habitat suitability in modified dryland landscapes. Due to the key trophic role of reptiles in dryland ecosystems, and the excellent thermal buffering capacity of underground shelters, we propose that ground burrows may be potentially considered as keystone structures in drylands, and require a similar level of protection to ‘habitat’ or ‘legacy’ trees in forested ecosystems.

Aggregation and site tenacity under downed logs in Salamandrella keyserlingii (Caudata: Hynobiidae)

Darhadyn Wetland, Mongolia, is located in a subarctic steppe–tundra climate, where salamanders are exposed to both extremely hot and cold environments. We hypothesized that log refugia provide an adaptive advantage to salamanders in these environments because the habitat availability hypothesis predicts that restricted habitat availability can cause aggregation that plays a role in the initial stages of the evolution of complex sociality. To test this hypothesis, we assessed whether a rare salamander species aggregated under a limited shelter resource. Many small vertebrates use terrestrial burrow refuges. While many salamander species also use burrows, Salamandrella keyserlingii at Darhadyn used only downed log refuges (i.e., restricted habitat availability). Some individuals displayed site tenacity to remain under a specific log, and one or more of the same individuals were located continually or frequently under the same logs. The majority of recapture events (96.8 %, 121/125) did not show any movements of salamanders between logs. Of the 300 capture events, 66 % were aggregating. The maximum number of individuals sharing a log refuge on the same day (i.e., sharing group size) ranged from 2 to 9. Individuals were resident nonrandomly in downed log refuges, i.e., an aggregation pattern was nonrandom. Based on these findings, we provided conservation measures such that total number of individuals captured per log over the course of the study (maximum number = 32) had a positive relationship to 1 of 7 explanatory variables (i.e., log decaying class in ascending order). Thus, the retention of decaying downed logs is important for the conservation of this species.

Spatial analysis of limiting resources on an island: diet and shelter use reveal sites of conservation importance for the Rottnest Island quokka

Context For conservation of any species, we need baseline data that will guide conservation planning strategies. Identifying plant resources used by animal species for food and shelter is the first important step towards fauna conservation. The second step is to determine the extent and distribution of these resources and thus identify prime habitat or habitat that could be improved through suitable management actions. This information provides the necessary spatial targeting required to make the most of few resources and a shortage of time. Aims Applying this model approach, we identified plant species used as food or shelter resources by the conservationally significant quokka (Setonix brachyurus) across Rottnest Island, Western Australia in the aftermath of the hottest and driest summer on record. Methods Dietary analysis was carried out using microhistological examination of plant cuticle remains from faecal samples for 67 locations across the island. Plants acting as diurnal rest shelters (n = 73 sites) were identified through observation of individuals flushed during surveys. Identifying key resources requires both a comprehensive analysis of the current use, as well as knowledge of availability of resources to determine selectivity. We therefore compared food plants or rest sites with a comprehensive survey of floristic diversity and abundance for 210 stratified-randomly located sites across the island. Key results We identified eight plant species that quokkas fed on preferentially and identified four plant species that were the principal shelter sites. We then used hyperspectral remote sensing data to map the distribution of these plant species to quantify their distribution and identify key habitat areas. Conclusions Understanding resource limitation over the most physiologically challenging time of the year provides important information for quokka conservation. Quokkas prefer Malvaceae species as food plants, and use dense, abundant shrubs for shelter. Implications Quokkas appear to have shifted their use of food plants since a previous study (50 years ago), likely reflecting modification of island vegetation due to anthropogenic influences, fire and herbivory over time. In the face of changing climate, this information will serve as an important guide towards conservation management actions on the island (e.g. future planning of revegetation and habitat protection/enhancement).

Remote sensing can locate and assess the changing abundance of hollow-bearing trees for wildlife in Australian native forests

Context Hollow-bearing trees are an important breeding and shelter resource for wildlife in Australian native forests and hollow availability can influence species abundance and diversity in forest ecosystems. A persistent problem for forest managers is the ability to locate and survey hollow-bearing trees with a high level of accuracy at low cost over large areas of forest. Aims The aim of this study was to determine whether remote-sensing techniques could identify key variables useful in classifying the likelihood of a tree to contain hollows suitable for wildlife. Methods The data were high-resolution, multispectral aerial imagery and light detection and ranging (Lidar). A ground-based survey of 194 trees, 96 Eucalyptus crebra and 98 E. chloroclada and E. blakelyi, were used to train and validate tree-senescence classification models. Key results We found that trees in the youngest stage of tree senescence, which had a very low probability of hollow occurrence, could be distinguished using multispectral aerial imagery from trees in the later stages of tree senescence, which had a high probability of hollow occurrence. Independently, the canopy-height model used to estimate crown foliage density demonstrated the potential of Lidar-derived structural parameters as predictors of senescence and the hollow-bearing status of individual trees. Conclusions This study demonstrated a ‘proof of concept’ that remotely sensed tree parameters are suitable predictor variables for the hollow-bearing status of an individual tree. Implications Distinguishing early stage senescence trees from later-stage senescence trees using remote sensing offers potential as an efficient, repeatable and cost-effective way to map the distribution and abundance of hollow-bearing trees across the landscape. Further development is required to automate this process across the landscape, particularly the delineation of tree crowns. Further improvements may be obtained using a combination of these remote-sensing techniques. This information has important applications in commercial forest inventory and in biodiversity monitoring programs.

Resource availability and use by Eurasian otters Lutra lutra in a heavily modified river‐canal system

The freshwater habitats of semi‐aquatic carnivores in Europe have undergone substantial alterations due to regulation and construction of artificial watercourses. We compared seasonal estimates of otter Lutra lutra food composition with concomitantly collected data on fish availability and otter holt location in a strongly human‐modified ecosystem comprising the upper stretches of the Wieprz‐Krzna Canal, the longest artificial waterway in Poland, and an associated regulated river. Concrete lining of the canal, extreme water level variation and regular vegetation clearance to enhance water flow substantially limited otter food and shelter resources, yet the canal offered attractive habitats for some fish and hibernating amphibians, while otter resting sites were available at the closely adjacent river. The taxonomic composition of fish in the otter diet, reconstructed based on faecal analysis, was largely reflected in electrofishing catches. Fish communities in our study area were numerically dominated by small‐sized species and otters fed on very small fish (median seasonal total lengths: 46‐54 mm). Either the smaller fish in the population were taken or prey sizes did not differ from those available. The significant contribution of amphibians and waterbirds to otter diet (seasonally 41‐75% in terms of biomass) indicated poor fish supplies for otters in the canal‐river system. High trophic diversity, compared to other otter studies in temperate climatic conditions, indicates that otters facing unstable food conditions exhibit great flexibility in their diet, which may facilitate colonisation of anthropogenic, depauperate environments. Otter occurrence provides little opportunity for conflict with human economic interests in ecosystems that are highly managed for purposes other than fish production. Since anthropogenic habitats are typically poor in some resources, such as shelter structures, their suitability for otters can be enhanced by ensuring good connectivity with nearby less‐disturbed habitats, where the necessary resources can be supplemented.

Provisioning Floral Resources to Attract Aphidophagous Hoverflies (Diptera: Syrphidae) Useful for Pest Management in Central Spain

Noncrop plant communities present on the boundaries or within crop fields are essential for the maintenance of functional biodiversity, affecting beneficial insect numbers and ecological fitness. Habitat manipulation is an increasingly studied strategy aimed at enhancing natural enemies of agricultural pests by providing feeding and shelter resources. In this study, six plant species selected from preliminary work were tested for their potential attractiveness to four common aphidophagous hoverflies species. Potential attractiveness was evaluated through observation of hoverfly feeding visits to replicated flower plots distributed in a randomized design. The combination of the selected species covered a 2-mo full-bloom period. Sphaerophoria scripta L. and Sphaerophoria rueppellii (Wiedeman) were the dominant hoverflies present throughout the sampling period, whereas Eupeodes corollae (F.) and Episyrphus balteatus (DeGeer) visits were less abundant and appeared only in the early season. Potential attractiveness varied among plant species. Calendula arvensis L. and Coriandrum sativum L. were the most visited species. C. arvensis received a high number of visits throughout a long period, whereas the visits to Co. sativum were concentrated in a short blooming period. These results suggest that habitat management by using these plant species may increase the abundance of hoverflies and could improve the biological control of aphid pests typical of spring-summer crops in open Mediterranean environments.