Predation on Common Wall Lizards: Survival Probabilities of Melanic Individuals

For estimation of predation plasticine models of prey animals are often used, because the soft material preserves imprints left by predators. We assumed that melanic common wall lizards (Podarcis muralis) disappear by selective predation faster than cryptic individuals and habitat features have important role in this process. We studied the survival probabilities of cryptic and melanic colored plasticine common wall lizard models in habitats with different background coloration on selected places near the city of Pécs (south Hungary), where melanic common wall lizards had been observed earlier. Contrary to our expectations the daily survival rates of melanic plasticine common wall lizards were somewhat higher in all three locations (sandstone quarry, stone wall, coal pit) than those of the cryptic ones, but these differences were not significant. Predators were mostly mammals, which left more marks on plasticine models than birds, but we could not show a preference of the body parts of prey. We concluded that rare occurrence of melanic common wall lizards in habitats near the city of Pécs is not due to predation pressure.

Abundance and Diurnal Time Activity Budget of the Threatened Species White-Headed Ducks (Anatidae: Oxyura leucocephala) in an Unprotected Area, Boussedra Marsh, Northeast Algeria

The white-headed duck is a globally threatened species and its populations have become fragmented and undergone major decline in recent decades. Changes including long-term abundance (five times from 2005 to 2018) and diurnal activity budget (2010−2011 and 2017−2018) with respect to the effect of habitat features at Boussedra marsh (unprotected area) were compiled in order to fill some gaps in the status and trend of North African populations. The population size of the white-headed duck decreased over years from 2010 to 2018 by about 52.81%, and was positively associated with interior vegetation area, but not significantly with water surface area. Trends of population dynamics differed among seasons, and the number was higher in wintering than breeding season. Sleeping (44.93%, 23.74%) and feeding (59.09%, 27.43%) were the dominant diurnal activities at both the years of study, respectively. Boussedra marsh plays an important ecological role as a diurnal forging habitat and reproduction site for this threatened species and as a shelter for other waterfowl.

Altered fire regimes modify lizard communities in globally endangered Araucaria forests of the southern Andes

Wildfire regimes are being altered in ecosystems worldwide. The density of reptiles responds to fires and changes to habitat structure. Some of the most vulnerable ecosystems to human-increased fire frequency are old-growth Araucaria araucana forests of the southern Andes. We investigated the effects of wildfires on the density and richness of a lizard community in these ecosystems, considering fire frequency and elapsed time since last fire. During the 2018/2019 southern summer season, we conducted 71 distance sampling transects to detect lizards in Araucaria forests of Chile in four fire “treatments”: (1) unburned control, (2) long-term recovery, (3) short-term recovery, and (4) burned twice. We detected 713 lizards from 7 species. We found that the density and richness of lizards are impacted by wildfire frequency and time of recovery, mediated by the modification of habitat structure. The lizard community varied from a dominant arboreal species (L. pictus) in unburned and long-recovered stands, to a combination of ground-dwelling species (L. lemniscatus and L. araucaniensis) in areas affected by two fires. Araucaria forests provided key habitat features to forest reptiles after fires, but the persistence of these old-growth forests and associated biodiversity may be threatened given the increase in fire frequency.

Polar bear (Ursus maritimus) use of the Cape Bathurst polynya and flaw lead

The Cape Bathurst polynya and flaw lead (CBP) are major, predictable habitat features with ≤15% ice cover in an otherwise ice-covered Beaufort Sea, and thought to provide hunting opportunities for polar bears (Ursus maritimus Phipps, 1774). We assessed 78 adult (female; with and without cubs) and subadult (male and female) polar bears’ use of the CBP from October – June, 2007–2014. The CBP was up to 725 km wide in autumn, ice-covered in winter, and <306 km wide in spring. Seventy-nine percent (n = 62) of the bears used the CBP (≥1 location <2.4 km, or one 4 h step length, from the CBP). Use was higher for solitary adult females and subadult males, which travelled faster with low turning angles along wider sections than females with offspring and subadult females. Bears were closest to the CBP during the spring hyperphagia season. While a wider CBP did not prevent crossing, bears primarily crossed from the coast towards pack ice at locations 53% narrower than areas not crossed. Bears might avoid crossing when it would require a long-distance swim. The CBP affects polar bear ecology by providing hunting habitat and a corridor that could increase prey encounters but may affect movement.

Short-Term Effects of Low-Head Barrier Removals on Fish Communities and Habitats

Barrier removal is increasingly being seen as the optimal solution to restore lotic habitat and fish communities, however, evidence of its efficacy is often limited to single sites or catchments. This study used a before–after methodology to examine the short-term (average, 541 days) effects of low-head (0.1–2.9 m) barrier removal at 22 sites distributed across Denmark and northern England on fish density, community, and river habitat responses. Following barrier removal, changes in the aquatic habitat were observed, such that the area immediately upstream of the former barrier location became shallower, with larger substrate and faster flow conditions. The reinstatement of this habitat was especially valuable in Danish streams, where these habitat features are rare, due to the naturally low gradients. Across all 22 sites fish species richness and diversity was similar before and after removal of barriers, likely because of the short study timescale (1–2 years). Across all sites combined, there was an increase in total fish density following barrier removal. A large increase in salmonid (Salmo trutta and Salmo salar) densities following barrier removal occurred at 7 out of 12 Danish sites. No similar response in salmonid density was observed at any of the UK sites which were mostly characterized by high channel gradients and short ponded zones. Two UK barrier removal sites showed marked increases in density of non-salmonid fish species. This study suggests that the removal of low-head barriers can be an effective method of restoring lotic habitats, and can lead to positive changes in fish density in the former ponded zone. The short-term effect of small barrier removal on the fish community is more variable and its effectiveness is likely to be determined by wider riverine processes.

Scale and Landscape Features Matter for Understanding Waterbird Habitat Selection

Clarifying species-environment relationships is crucial for the development of efficient conservation and restoration strategies. However, this work is often complicated by a lack of detailed information on species distribution and habitat features and tends to ignore the impact of scale and landscape features. Here, we tracked 11 Oriental White Storks (Ciconia boyciana) with GPS loggers during their wintering period at Poyang Lake and divided the tracking data into two parts (foraging and roosting states) according to the distribution of activity over the course of a day. Then, a three-step multiscale and multistate approach was employed to model habitat selection characteristics: (1) first, we minimized the search range of the scale for these two states based on daily movement characteristics; (2) second, we identified the optimized scale of each candidate variable; and (3) third, we fit a multiscale, multivariable habitat selection model in relation to natural features, human disturbance and especially landscape composition and configuration. Our findings reveal that habitat selection of the storks varied with spatial scale and that these scaling relationships were not consistent across different habitat requirements (foraging or roosting) and environmental features. Landscape configuration was a more powerful predictor for storks’ foraging habitat selection, while roosting was more sensitive to landscape composition. Incorporating high-precision spatiotemporal satellite tracking data and landscape features derived from satellite images from the same periods into a multiscale habitat selection model can greatly improve the understanding of species-environmental relationships and guide efficient recovery planning and legislation.

Light Detection and Ranging (LiDAR) Assisted Detection of Rock Outcrops in Appalachian Hardwood Forests

The identification of small habitat features embedded within forest ecosystems is a challenge for many wildlife inventory and monitoring programs, especially for those involving rock outcrop specialist taxa. Rock outcrops are often difficult to remotely detect in dense Appalachian hardwood forests, as most outcrops remain hidden under the forest canopy and therefore invisible when relying on aerial orthoimagery to pinpoint habitat features. We investigated the ability for light detection and ranging (LiDAR) point cloud data to identify small rock outcrops during the environmental assessment phase of a proposed management project on the Jefferson National Forest in Virginia, USA. We specifically compared this approach to the visual identification of rock outcrops across the same area using aerial orthoimagery. Our LiDAR-based approach identified three times as many rock outcrop sites as aerial orthoimagery, resulting in the field-verification of four times as many previously-unknown populations of green salamanders Aneides aeneus, a rock outcrop specialist amphibian of high conservation concern, than would have been possible if relying on aerial orthoimagery alone to guide surveys. Our results indicate that LiDAR-based methods may provide an effective, efficient, and low-error approach that can remotely identify below-canopy rock outcrops embedded within Appalachian forests, especially when researchers lack pre-existing knowledge of local terrain and the location of habitat features.

Cultural conformity and persistence in Dickcissel song are higher in locations in which males show high site fidelity

Dickcissel (Spiza americana) males occupying territories in cropland sites produced songs that were less similar on average to other Dickcissel songs in their neighborhood than did Dickcissels living in grasslands, where conformity to the local vocal culture was higher. Further, Dickcissel vocal culture changed more quickly over time in cropland sites relative to grassland sites. These differences may have resulted from the lower site fidelity we observed in Dickcissel males in cropland sites relative to grassland sites. We expected this link with site fidelity because we hypothesized that conformity to local culture in Oscine songbirds and the persistence of culture over time and space are promoted by habitats that facilitate stable populations. In contrast, sites in which habitat features cause rapid population turnover provide more territory vacancies and so more opportunities for colonization. Colonization should drive cultural change, either through adult colonists importing foreign cultural variants or young colonists making errors as they learn the local song. This potential link between population turnover and cultural stability may apply to animal cultures more broadly and so may be a fruitful area for further research. Besides the link between site fidelity and cultural change over time, we also investigated the possibility that habitats with different levels of site fidelity might show differences in the spatial scale of song similarity. However, we found no evidence of such a difference. Finally, although our conclusions regarding conformity and change in vocal culture were based on many recorded songs, automated assessments of song similarity imprecisely estimated the overall degree of song similarity. Thus, we may have underestimated the strength of the effects of time and distance on song similarity.

Long-term monitoring reveals topographical features and vegetation explain winter habitat use of an arctic rodent

The quality of wintering habitats, such as depth of snow cover, plays a key role in sustaining population dynamics of arctic lemmings. However, few studies so far investigated habitat use during the arctic winter. Here, we used a unique long-term time series to test whether lemmings are associated with topographical and vegetational habitat features for their wintering sites. We examined yearly numbers and distribution of 22,769 winter nests of the collared lemming Dicrostonyx groenlandicus (Traill, 1823) from an ongoing long-term research on Traill Island, Northeast Greenland, collected between 1989 and 2019, and correlated this information with data on dominant vegetation types, elevation and slope. We found that the number of lemming nests was highest in areas with a high proportion of Dryas heath, but was also correlated with other vegetation types, suggestingsome flexibility in resource use of wintering lemmings. Furthermore, lemmings showed a higher use for sloped terrain, probably as it enhances the formation of deep snow drifts which increases the insulative characteristics of the snowpack and protection from predators. With global warming, prime lemming winter habitats may become scarce through alteration of snow physical properties, potentially resulting in negative consequence for the whole community of terrestrial vertebrates.

A local scale evaluation of spatial sampling bias in the Atlas of Australian Birds

ABSTRACTThe reliability of ‘citizen science’ datasets where volunteers are free to choose sampling locations is not clear. This study examined local (‘patch’) scale spatial sampling patterns in the Atlas of Australian Birds and then compared reporting rates, i.e. the proportion of sampling units in which a given species was present, from a sample of atlas points with those from a regular sample. Three sites that have been were surveyed sequentially between January–May 2017: Killawarra Forest, Victoria, Coolah Tops National Park and Pilliga Nature Reserve, New South Wales. Spatial bias in atlas sampling patterns was evident as clusters at tourist areas and special habitat features and linear patterns along roads and creek lines. Atlas samples overestimated reporting rates for species with spatial distributions that were concordant with those sampling patterns and vice versa. At least two-fold differences in atlas/regular sample reporting rate ratios were detected for between 13–15% of non-rare species (with reporting rates ≥ 0.08). Concerns are raised that spatial sampling bias is common in the atlas and affects a variety of species, that popular sites may not be representative of habitat patches and that a large proportion of surveys are being filtered out in data analyses.