Bird Tracks Research Articles

Early Cretaceous dinosaur, bird and turtle tracks from the Lanzhou-Minhe Basin, Gansu Province, Northwest China

The Early Cretaceous avian ichnofauna of Laurasia, particularly in East Asia, is remarkably abundant. The northwestern region of China is the most productive area for bird tracks. Recently, four avian-dominated track sites have been discovered in the Cretaceous Lanzhou-Minhe Basin of Gansu, where the shorebird track Koreanaornis, the ankylopollexian track Caririchinium and the turtle track Chelonipus occur. The Kongjiasi site yields a new type of the fluvio-lacustrine Chelonipus ichnocoenosis related to birds, which was previously defined to include only non-avian theropods and turtles. The site is associated with a waterfront foraging site of a Cretaceous shorebird which might be due to the invertebrate-rich substrate. The sole association of both bird and other theropod tracks with Chelonipus ichnocoenosis may indicate a difference in the appetite of avian and non-avian theropods for littoral foraging sites. And a review of the global turtle track-related ichnofauna and ichnocoenosis may offer new insights into the qualitative speculation of palaeobathymetry in riparian environments.

Wind gradient exploitation during foraging flights by black skimmers (Rynchops niger).

Birds commonly exploit environmental features such as columns of rising air and vertical windspeed gradients to lower the cost of flight. These environmental subsidies may be especially important for birds that forage via continuous flight, as seen in black skimmers. These birds forage through a unique behavior, called skimming, where they fly above the water surface with their mandible lowered into the water, catching fish on contact. Thus, their foraging flight incurs costs of moving through both air and water. Prior studies of black skimmer flight behavior have focused on reductions in flight cost due to ground effect, but ignored potential beneficial interactions with the surrounding air. We hypothesized a halfpipe skimming strategy for skimmers to reduce the foraging cost by taking advantage of the wind gradient, where the skimmers perform a wind gradient energy extraction maneuver at the end of a skimming bout through a foraging patch. Using video recordings, wind speed and wind direction measurements, we recorded 70 bird tracks over 4days at two field sites on the North Carolina coast. We found that while ascending, the skimmers flew more upwind and then flew more downwind when descending, a pattern consistent with harvesting energy from the wind gradient. The strength of the wind gradient and flight behavior of the skimmers indicate that the halfpipe skimming strategy could reduce foraging cost by up to 2.5%.

Drivers of flight altitude during nocturnal bird migration over the North Sea and implications for offshore wind energy

AbstractEach year, millions of birds migrate nocturnally over the North Sea basin, an area designated for significant offshore wind energy development. Wind turbines can harm aerial wildlife through collisions and barrier effects, especially when birds fly at low altitudes below the wind turbine rotor tip. We aim to quantify seasonal and nightly differences in flight altitudes of nocturnal bird migration over the North Sea and identify how weather influences low‐altitude flight to inform wind turbine curtailment procedures for reducing bird fatalities. We used bird tracking radars at Borssele and Luchterduinen offshore wind parks, 22 and 23 km from the western Dutch coast, to monitor altitude distributions during migration. We show that median flight altitude was higher in spring compared to autumn at Borssele (spring: 285.5 m, autumn: 169.2 m; p < .001, effect size [ES] = 0.0001) and Luchterduinen (spring: 133.8 m, autumn: 126.0 m; p < .001, ES = 0.002) and below wind turbine rotor tip in both seasons. On most nights in both seasons, the majority of migrants flew predominantly at low altitudes, except for intense migration nights in spring in Borssele where, on 87% of these nights, migration mainly occurred at high altitudes. The most important predictors of low‐altitude migration in both seasons were day of year and wind assistance. Birds chose altitudes with the most favorable wind conditions for migration in both seasons. The relationship between day of year and low‐altitude migration fraction suggests that different species migrate at different altitudes. In spring, birds were flying lower at the beginning and the end of the night, reflecting departures and arrivals of birds, while radar location in autumn was a good predictor of low‐altitude flights, indicating that different local migratory axes have distinct altitude distributions. Our findings suggest that mitigation measures offshore may be more effective during autumn than spring, especially on nights with more supportive wind conditions at altitudes below 300 m.

Mapping seabird vulnerability to offshore wind farms in Norwegian waters

IntroductionOffshore wind energy development (OWED) has been identified as a major contributor to the aspired growth in Norwegian renewable energy production. Spatially explicit vulnerability assessments are necessary to select sites that minimize the harm to biodiversity, including seabird populations. Distributional data of seabirds in remote areas are scarce, and to identify vulnerable areas, species, and seasons it is necessary to combine data sets and knowledge from different sources.MethodsIn this study, we combined seabird tracking data, data from dedicated coastal and seabird at-sea surveys, and presence-only data from citizen science databases to develop habitat suitability maps for 55 seabird species in four seasons throughout the Norwegian exclusive economic zone; in total 1 million km2 in the Northeast Atlantic. The habitat suitability maps were combined with species-specific vulnerability indicators to yield maps of seabird vulnerability to offshore wind farms (OWFs). The resulting map product can be used to identify the relative vulnerability of areas prospected for OWED with respect to seabird collision and habitat displacement. More detailed assessments can be done by splitting the spatial indicators into seasonal and species-specific components.Results and discussionAssociated with higher diversity of seabirds near the coast, the cumulative vulnerability indicator showed a strong declining gradient from the coast to offshore waters while the differences in vulnerability between ocean areas and seasons were negligible. Although the present map product represents the best currently available knowledge, the indicators are associated with complex uncertainties related to known and unknown sampling biases. The indicators should therefore be used cautiously, they should be updated regularly as more data become available, and we recommend that more detailed environmental impact assessments based on dedicated seabird surveys, tracking of birds from potentially affected populations and population viability analyses are conducted in areas ultimately selected for OWED.

Incomplete isolation in the nonbreeding areas of two genetically separated but sympatric short-tailed albatross populations

The short-tailed albatross Phoebastria albatrus, a globally Vulnerable species recovering from near-extinction, breeds mainly on 2 island groups in the north-western Pacific: Torishima and Senkaku Islands. Recently, it became clear that this is a species complex, composed of 2 populations (‘Torishima’ and ‘Senkaku’ types) that are distinct from both genetic and morphological perspectives, and which mate assortatively on Torishima. We tested the hypothesis of premating isolation as a possible mechanism for genetic differentiation and shifted breeding date in short-tailed albatrosses. Using light-based geolocation and molecular analysis, we examined whether adults from the 2 populations breeding on Torishima differed in their at-sea distribution during the nonbreeding period (June-September) and in their return dates. From 22 bird tracks collected from 12 birds over 4 yr, we identified 2 distinct nonbreeding areas: around the Aleutian Islands in the Bering Sea and near the Kuril Islands in the Okhotsk Sea. All 6 tracks of Torishima-type birds migrated directly to the Bering Sea in all years. In contrast, most of the Senkaku-type birds migrated along northeast Japan to the Okhotsk Sea (9 tracks), with the others moving to the Bering Sea (7 tracks). There was no clear difference in the dates of return to Torishima between the 2 bird types. Overall, no absolute pre-mating isolation in space or time was observed in short-tailed albatrosses, but we highlighted notable divergences in the nonbreeding distribution of both types. This result suggests that Torishima- and Senkaku-type populations should be treated as separate management units.

A standardized protocol for assessing the performance of automatic detection systems used in onshore wind power plants to reduce avian mortality

While wind power plants are an important contribution to the production of renewable energy to limit climate change, collision mortality from turbines is a danger for birds, including many protected species. To try to mitigate collision risks, automatic detection systems (ADSs) can be deployed on wind power plants; these work by detecting incoming birds using a detection/classification process and triggering a specific reaction (scaring off the bird or shutting down the turbine). Nonetheless, bird fatalities still occur at ADS-equipped wind power plants, which raises the question of the performance of these tools. To date, the lack of a transparent, peer-reviewed experimental process to compare the performance of types of ADS has meant there is no robust protocol to assess these systems.With the aim of filling this gap, we developed two standardized protocols that provide objective and unbiased assessments of the performance of different types of ADS, based on their probability of detecting/classifying birds at risk of collision. Both protocols rely on precise 3D tracking of wild birds by human observers using a laser rangefinder, and the comparison of these tracks with those detected and recorded by an ADS. The first protocol evaluates a system's general performance, generating comparable data for all types of ADS. In this protocol, detection/classification probability is estimated conditional on several abiotic and biotic environmental factors such as bird size, distance from the target, the flight angle and azimuth of the bird, as well as weather conditions. The second protocol aims to verify that the performance of an ADS installed on a given wind power plant complies with its regulatory requirements. In this protocol, detection/classification probability is specifically estimated for a given target species at a given regulatory detection distance. This protocol also estimates the proportion of time an ADS is functional on site over a year, and the proportion of reaction orders successfully operated by wind turbines. These protocols have been field-tested and made publicly available for use by government agencies and wind power plant operators.

WURRANDERRA’S SYMBOLS: AN EXPLORATION AND CONTEXTUALISATION OF THE THURK PETROGLYPH SITE (KINGSTON-ON-MURRAY) ON THE MURRAY RIVER, SOUTH AUSTRALIA

This article describes and contextualises the rock art at the Thurk Petroglyph Site on the Murray River in South Australia using multiple methods. The Thurk Aboriginal engravings comprise at least 524 motifs made up predominantly of geometric line elements as well as a small number of other ‘simple’ geometric motifs, two ‘bird tracks’, one figurative design (a ‘fish’) and a possible anthropomorphous figure. This paper provides the first synthesis of rock art sites/complexes and motifs from other sites on the Murray River as well as visual symbols recorded from senior Aboriginal ‘knowledge carriers’. These syntheses allow us to consider the relationship of Thurk to other cultural places and to highlight and honour the traditional knowledges and beliefs which underpin the rock art. Thurk’s placement within the riverscape, its unique geological canvas, lack of observable ‘domestic’ archaeological evidence combined with it being the likely upstream extent of Murray River rock art in South Australia contribute additional dimensions to its cultural significance. That Thurk’s rock art, and the broader site, have been desecrated by gratuitous graffiti, vandalism and infrastructure brings into sharp focus Australia’s poor record of heritage protection and provides a challenge to current and future generations of non-Aboriginal people to remedy this past.

A framework for post‐processing bird tracks from automated tracking radar systems

Abstract Radar is an effective tool for continuous monitoring and quantification of aerial bird movement and used to study migration and local flight behaviour. However, systems with automated tracking algorithms do not provide the level of processing sufficient to guarantee reliable data. Therefore, post‐processing such radar data is required but often non‐trivial, especially in challenging environments such as open sea. We present a post‐processing framework that implements knowledge of the radar system and bird biology to filter the data and retrieve reliable, high‐quality tracking data. The framework is split into three modules, each with a specific aim: (I) sub‐setting based on prior knowledge of the radar system and bird flight, (II) improving bird track quality and (III) detecting and removing spatio‐temporal sections of data that have a clear bias for false observations. The effectiveness of the framework is demonstrated with a case study comparing track densities inside and outside an offshore wind farm, and by applying the workflow to a dataset of visually validated radar tracks. Application of Module I resulted in a dataset of 520.894 bird tracks (19.5% of total data) within a 10.4 km2 area. Additionally, 18.734 tracks were corrected for geometric errors in Module II, and Module III identified 236 of 719 observation hours and an area of 1.55 km2 as unreliable for spatio‐temporal analysis. No difference in track densities was found between the area inside and outside the wind farm when using the post‐processed data, whereas using the unprocessed bird tracks, lower track densities were observed outside the wind farm. Of the visually validated radar tracks, the framework removed 85% of false positive bird tracks, while retaining 80% of true positive bird tracks. The framework provides a logical workflow to increase the reliability and quality of a bird radar dataset while being adaptable to the radar system and its surroundings. This is a first step towards standardising the post‐processing methodology for automated bird radar systems, which can facilitate comparative analyses of bird movement in space and time and improve the quality of ecological impact assessments.

The oldest fossil bird-like footprints from the upper Triassic of southern Africa.

Footprint morphology reflects the anatomy of the trackmaker's foot and is direct evidence for the animal's behaviour. Consequently, fossil tracks can be used to infer ancient diversity, ethology, and evolutionary trends. This is particularly useful for deep-time intervals during which the early history of an animal group is reliant upon limited fossil skeletal material. Fossil tracks of early birds and theropods, the co-existing dinosaurian ancestors of birds, co-occur in the rock record since the Early Cretaceous. However, the evolutionary transition from dinosaur to bird and the timing of the birds' origin are still contested. Skeletal remains of the basal-most birds Aurornis, Anchiornis, Archaeopteryx and Xiaotingia are Middle to Late Jurassic, while tracks with tentative bird affinities, attributed to dinosaurs, are known from as early as the Late Triassic. Here, we present numerous, well-provenanced, Late Triassic and Early Jurassic tridactyl tracks from southern Africa, with demonstrable bird-like affinities, predating basal bird body fossils by c. 60 million years.

Earliest known Gondwanan bird tracks: Wonthaggi Formation (Early Cretaceous), Victoria, Australia

The fossil record for Cretaceous birds in Australia has been limited to rare skeletal material, feathers, and two tracks, a paucity shared with other Gondwanan landmasses. Hence the recent discovery of 27 avian footprints and other traces in the Early Cretaceous (Barremian-Aptian, 128–120 Ma) Wonthaggi Formation of Victoria, Australia amends their previous rarity there, while also confirming the earliest known presence of birds in Australia and the rest of Gondwana. The avian identity of these tracks is verified by their tridactyl forms, thin digits relative to track lengths, wide divarication angles, and sharp claws; three tracks also have hallux imprints. Track forms and sizes indicate a variety of birds as tracemakers, with some among the largest reported from the Early Cretaceous. Although continuous trackways are absent, close spacing and similar alignments of tracks on some bedding planes suggest gregariousness. The occurrence of this avian trace-fossil assemblage in circumpolar fluvial-floodplain facies further implies seasonal behavior, with trackmakers likely leaving their traces on floodplain surfaces during post-thaw summers.

Acahualinca, Nicaragua, a scientifically significant site of ancient human footprints in the New World

Abstract Ancient human footprints have been known from Managua, Nicaragua, since the 1880s. The main footprint site, long preserved in the Acahualinca Tracks Museum ( Huellas de Acahualinca ), reveals hundreds of human footprints that represent a minimum of 12 clearly defined trackways and a trampled trail or path. Deer, opossum and bird tracks are also present at Acahualinca, and bison and tapir tracks have been documented from the nearby and stratigraphically equivalent El Recreo site. The age of the Acahualinca footprints is controversial, but the best current estimate is about 2–2.2 ka BP. The Acahualinca site is one of the most scientifically important human footprint sites known from the Holocene. It exhibits footprints that are very abundant, well-preserved, accessible for study and part of a large sample that demonstrates variation within a single population. The Acahualinca site has historical, cultural and archaeological importance in preserving at least two intervals of human occupation, that of the footprints and of the ceramics in much younger layers. Its significance to anthropology and palaeontology as a sub-fossil footprint locality is clear and the volcanological history of the area is intimately related to determining the age and the circumstances of footprint registration at Acahualinca. The Acahualinca footprints merit geoheritage status.

Dynamic Temperature Compensation of Pressure Sensors in Migratory Bird Biologging Applications

This article proposes an improved dynamic quantum particle swarm optimization (DQPSO) algorithm to optimize a radial basis function (RBF) neural network for temperature compensation of pressure sensors used in tracking and monitoring wild migratory birds. The algorithm incorporates a temperature-pressure fitting model that includes temperature rate of change and gradient reference terms. It also includes a loss function that considers fitting accuracy and complexity, thereby improving the robustness of the sensor for complex temperature variations. The calibration experiments revealed that after implementation, the average absolute error of the pressure sensor output during dynamic temperature changes was reduced from 145.3 Pa to 20.2 Pa. This reduction represents an 86% improvement over the commercial polynomial compensation method, and the DQPSO approach significantly outperformed traditional feedforward network models. Finally, the algorithm was deployed and verified in an embedded environment for low-power, high-precision, real-time pressure compensation during the tracking and monitoring of wild migratory birds.

A preliminary study of the winter roosting behaviour of four woodland passerines

ABSTRACT Capsule Radio-tracking of four woodland passerine species reveals variation in winter roost site selection within and between species. Aims To evaluate methods for studying winter roosting behaviour in woodland passerines and to collect preliminary data on intra- and inter-specific differences in roost site characteristics and spatial arrangement. Methods Ten woodland birds (three Eurasian Blackbirds Turdus merula, three Dunnocks Prunella modularis, two Great Tits Parus major and two European Robins Erithacus rubecula), were fitted with a tail-mounted Lotek PicoPip AG337 VHF radio tag (January to March 2022). Tagged birds were located by triangulation, and nightly winter roost locations identified and characterized. A geographic information system was used to quantify roost site fidelity, roosting height and types of habitats used. Results Manual tracking of birds with radio tags is a cost effective and appropriate method for studying passerine winter roosting behaviour. Sample sizes were too small to allow exploration of significant differences between sites, age and sex. European Robins showed the greatest site fidelity in relation to between-night roost positions, with Eurasian Blackbird, Great Tit and Dunnock being more variable in the sites chosen between nights. Eurasian Blackbird and Great Tit roost sites were generally higher above the ground (up to 6 m), compared to European Robins and Dunnocks (all sites less than 4 m above the ground). Eurasian Blackbirds varied the most in the number of habitats used for roost sites, and European Robins showed the least variation. Only three out of 11 habitat types (bramble Rubus sp, laurel Prunus sp. and Sycamore Acer pseudoplatanus with Ivy Hedera helix) were used by more than one species as a roosting habitat. Conclusion Further research should focus on: (1) habitat use in relation to relative availability; (2) increasing samples sizes to allow comparison of factors such as age, sex and sites; (3) the impact of supplementary feeding on roosting behaviour; (4) quantifying the thermal properties of roost sites.

A Gated-Recurrent-Unit-Based Interacting Multiple Model Method for Small Bird Tracking on Lidar System.

Lidar presents a promising solution for bird surveillance in airport environments. However, the low observation refresh rate of Lidar poses challenges for tracking bird targets. To address this problem, we propose a gated recurrent unit (GRU)-based interacting multiple model (IMM) approach for tracking bird targets at low sampling frequencies. The proposed method constructs various GRU-based motion models to extract different motion patterns and to give different predictions of target trajectory in place of traditional target moving models and uses an interacting multiple model mechanism to dynamically select the most suitable GRU-based motion model for trajectory prediction and tracking. In order to fuse the GRU-based motion model and IMM, the approximation state transfer matrix method is proposed to transform the prediction of GRU-based network into an explicit state transfer model, which enables the calculation of the models' probability. The simulation carried out on an open bird trajectory dataset proves that our method outperforms classical tracking methods at low refresh rates with at least 26% improvement in tracking error. The results show that the proposed method is effective for tracking small bird targets based on Lidar systems, as well as for other low-refresh-rate tracking systems.

How to improve the accuracy of height data from bird tracking devices? An assessment of high-frequency GPS tracking and barometric altimetry in field conditions

BackgroundIn the context of rapid development of wind energy infrastructure, information on the flight height of birds is vital to assess their collision risk with wind turbines. GPS tags potentially represent a powerful tool to collect flight height data, yet GPS positions are associated with substantial vertical error. Here, we assessed to what extent high-frequency GPS tracking with fix intervals of 2–3 s (GPS remaining turned on between fixes), or barometric altimetry using air pressure loggers integrated in GPS tags, improved the accuracy of height data compared to standard low-frequency GPS tracking (fix interval ≥ 5 min; GPS turned off between fixes).ResultsUsing data from 10 GPS tag models from three manufacturers in a field setting (194 tags deployed on free-living raptors), we estimated vertical accuracy based on periods when the birds were stationary on the ground (true height above ground was approximately zero), and the difference between GPS and barometric height in flight. In GPS height data, vertical accuracy was mainly driven by noise (little bias), while in barometric data, it was mostly affected by bias (little noise). In high-frequency GPS data, vertical accuracy was improved compared to low-frequency data in each tag model (mean absolute error (AE) reduced by 72% on average; range of mean AE 2–7 vs. 7–30 m). In barometric data, vertical accuracy did not differ between high- and low-frequency modes, with a bias of − 15 to − 5 m and mean AE of 7–15 m in stationary positions. However, the median difference between GPS and barometric data was smaller in flight positions than in stationary positions, suggesting that the bias in barometric height data was smaller in flight. Finally, simulations showed that the remaining vertical error in barometric and high-frequency GPS data had little effect on flight height distributions and the proportion of positions within the collision risk height range, as opposed to the extensive noise found in low-frequency GPS data in some tag models.ConclusionsBarometric altimetry may provide more accurate height data than standard low-frequency GPS tracking, but it involves the risk of a systematic error. Currently, high-frequency GPS tracking provides highest vertical accuracy and may thus substantially advance the study of wind turbine collision risk in birds.

Coastal raptors and raiders: New bird tracks in the Pleistocene of SW iberian Peninsula

Avian traces occurring in Pleistocene aeolianite and beach deposits are rare and relatively poorly known, despite being good paleoenvironmental indicators. Passeriform and raptorial birds are especially rare in the track fossil record. Exceptional tracksites were found in the Malhão formation, a Pleistocene coastal aeolianite unit from the SW mainland Portugal, with subunits in the interval ∼187 to ∼27 ka. Two new forms of avian traces were identified, Corvidichnus odemirensis and Buboichnus vicentinus - attributed to the locomotion of Western jackdaw and the locomotion and predation/feeding behaviour of a large Eagle-owl. The last trace fossil may correspond to the first evidence of a raptorial bird-prey interaction found in action in the fossil record. Typical shorebird tracks and trackways attributed to gulls (Laridae) and curlews, and others tentatively compared with Rallidae, such as Eurasian coot, are also discussed within the aeolianite ichnoassemblages. The tracks here described are the first avian ichnotaxa from the Pleistocene of Europe.

An Efficient Method for Monitoring Birds Based on Object Detection and Multi-Object Tracking Networks.

To protect birds, it is crucial to identify their species and determine their population across different regions. However, currently, bird monitoring methods mainly rely on manual techniques, such as point counts conducted by researchers and ornithologists in the field. This method can sometimes be inefficient, prone to errors, and have limitations, which may not always be conducive to bird conservation efforts. In this paper, we propose an efficient method for wetland bird monitoring based on object detection and multi-object tracking networks. First, we construct a manually annotated dataset for bird species detection, annotating the entire body and head of each bird separately, comprising 3737 bird images. We also built a new dataset containing 11,139 complete, individual bird images for the multi-object tracking task. Second, we perform comparative experiments using a state-of-the-art batch of object detection networks, and the results demonstrated that the YOLOv7 network, trained with a dataset labeling the entire body of the bird, was the most effective method. To enhance YOLOv7 performance, we added three GAM modules on the head side of the YOLOv7 to minimize information diffusion and amplify global interaction representations and utilized Alpha-IoU loss to achieve more accurate bounding box regression. The experimental results revealed that the improved method offers greater accuracy, with mAP@0.5 improving to 0.951 and mAP@0.5:0.95 improving to 0.815. Then, we send the detection information to DeepSORT for bird tracking and classification counting. Finally, we use the area counting method to count according to the species of birds to obtain information about flock distribution. The method described in this paper effectively addresses the monitoring challenges in bird conservation.

Guess who? Evaluating individual acoustic monitoring for males and females of the Tawny Pipit, a migratory passerine bird with a simple song

Individual acoustic monitoring (IAM), based on the analysis of vocal cues, is particularly suitable for the identification and tracking of birds with temporally stable song or call characteristics. Unlike mark-recapture methods, IAM does not require the physical manipulation of individuals, which can have long-lasting behavioural effects. So far, IAM has usually focused on males, as singing females tend to be overlooked in temperate zones. Here, we evaluated the suitability of IAM for both sexes in an isolated population of the Tawny Pipit (Anthus campestris, Motacillidae), a migratory Palearctic species critically endangered in Central Europe, for which female singing has been occasionally documented. We confirmed that songs of all 101 studied individuals, both males and females, were individually distinct. Most individuals used only a single song type in their repertoires, with only three males using two. Of 45 ringed males (that could be unambiguously recognized visually), only two changed their song structure to some extent, either within or between seasons. Multiple individuals often sang structurally similar song types, which nevertheless consistently differed in minor characteristics; such differences were detectable by visual inspection and also affected quantitative analyses of song similarity. Songs sung by females did not have any apparent sex-specific characteristics. Unlike previously suggested, females did not adapt their vocalization to their breeding partner, and we presume their song is also temporally stable. Our findings support IAM as a reliable approach for studying the behaviour and ecology of this passerine species with a small repertoire and simple songs.

Combining bird tracking data with high-resolution thermal mapping to identify microclimate refugia

Elevated temperatures can have a range of fitness impacts, including high metabolic cost of thermoregulation, hence access to microclimate refugia may buffer individuals against exposure to high temperatures. However, studies examining the use of microclimate refugia, remain scarce. We combined high resolution microclimate modelling with GPS tracking data as a novel approach to identify the use and availability of cooler microclimate refugia (sites > 0.5 °C cooler than the surrounding landscape) at the scales experienced by individual animals. 77 little bustards (Tetrax tetrax) were tracked between 2009 and 2019. The 92,685 GPS locations obtained and their surrounding 500 m areas were characterised with hourly temperature and habitat information at 30 m × 30 m and used to determine microclimate refugia availability and use. We found that the semi-natural grassland landscapes used by little bustards have limited availability of cooler microclimate areas—fewer than 30% of the locations. The use of cooler microclimate sites by little bustards increased at higher ambient temperatures, suggesting that individuals actively utilise microclimate refugia in extreme heat conditions. Microclimate refugia availability and use were greater in areas with heterogeneous vegetation cover, and in coastal areas. This study identified the landscape characteristics that provide microclimate opportunities and shelter from extreme heat conditions. Little bustards made greater use of microclimate refugia with increasing temperatures, particularly during the breeding season, when individuals are highly site faithful. This information can help identify areas where populations might be particularly exposed to climate extremes due to a lack of microclimate refugia, and which habitat management measures may buffer populations from expected increased exposure to temperature extremes.

Bird Tracks from the Cretaceous Sanbukdong Formation, Gunsan City, Jeollabuk-do, Korea

Bird Tracks from the Cretaceous Sanbukdong Formation, Gunsan City, Jeollabuk-do, Korea