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The conundrum of turtle and tortoise basking: A critical review

  •  17 May 2024

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Turtles and tortoises may bask out of water, at the water surface, or in deep water, during the day or at night, and with or without exposure to sunlight or another heat source. Basking's primary function is thermoregulatory warming, but evidence supports several other purposes. Unambiguous use of the term basking requires the specification of distinguishing criteria and the attachment of qualifiers to stipulate time of day, medium, and environmental exposure.

Open access

Mandibular morphology in four species of insectivorous bats: the impact of sexual dimorphism and geographical differentiation

  •  17 May 2024

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Insectivorous bats exhibit fascinating morphological adaptations linked to their diverse feeding habits. Our study, using 2D geometric morphometrics, investigated mandible variation among four species across Eurasia and North Africa. Sexual dimorphism in mandible size was observed in the common noctule and Daubenton's bat, with females being larger than males, and geographical factors such as latitude and longitude influenced the size and shape variations, respectively. A complex interplay of factors might be influencing this intriguing intraspecific morphological variation and more detailed ecological information is needed to assess this variation further.

Effects of growing season and individual growth rates on the occurrence of larval overwintering in Otton frog tadpoles

  •  15 May 2024

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This study investigated the effect of the growing season and individual growth rates on the occurrence of larval overwintering in Babina subaspera by laboratory-rearing experiments. Tadpoles with higher growth rates were more likely to metamorphose before winter, but the threshold growth rate was higher for tadpoles that hatched later in the season. The results suggested that slow-growing tadpoles with insufficient time until the onset of winter would gain higher fitness by metamorphosing after winter.

Open access

Cozy den or winter walk: the effects of climate and supplementary feeding on brown bear winter behavior

  •  11 May 2024

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Supplemental feeding sites in combination with predicted mild winters and prolonged natural food availability suggest that the use of hibernation as an energy-saving strategy to overcome severe environmental conditions may decrease in the future. Our data suggest that an abundance of human-provided food resources during winter may facilitate the emergence of different wintering strategies in brown bears, ranging from a single hibernation event up to five stationary periods, while some bears remained partly or completely active throughout the winter.

Open access

A new view of territoriality in large eagles: the territory pre‐exists regardless of their occupants

  •  6 May 2024

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Investigating the plasticity of territory boundaries, the shape of territories and how territories can be modified depending on their owners is important to deepen our knowledge of the behaviour of territorial species. We analysed the variation and tested the similarity of the distribution area of individuals from the same territory between 2015 and 2021, using data from 51 Bonelli's eagles (Aquila fasciata) from 22 different territories, tagged with GPS/GSM transmitters in eastern Spain. We also analysed the changes in territory size and shape following the replacement of territory owners either by a single individual or by the whole pair. Our results show that territories retain the same shape and extent regardless of the occupying members, and that their boundaries change little over time. Identifying and maintaining large eagle territories, regardless of their owners, is therefore key to ensuring the long-term recovery of these threatened species.

Ecological niche variation drives morphological differentiation in tropical stream‐dwelling newts from Indochina

  •  29 April 2024

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Morphological diversity within organisms can arise from factors other than genetic diversity alone, and local adaptations and combinations of various factors are also involved in shaping morphology. We investigated the relationship between morphological diversity and ecological niche divergence within two related tropical stream-dwelling newt species from Indochina: Paramesotriton deloustali and P. guangxiensis. We identified significant intra- and interspecific morphological and niche differentiation across five populations of the two newt species, suggesting that newt morphology is responsive to environmental factors. A significant negative relationship was observed only between ecological niche similarity and geographic distance among various combinations of factors, indicating that the distinct morphology of the study species mirrors ecological adaptation.

Hindlimb myology in two piscivorous raptorial birds: a quantitative comparison of the osprey and the white‐tailed sea eagle (Aves, Accipitriformes)

  •  28 April 2024

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The hindlimb musculature of Pandion haliaetus and Haliaeetus albicilla showed remarkable similarities, indicating a strong preservation of muscle traits essential for their raptorial abilities. Specifically, the flexor muscles —, flexor hallucis longus, tibialis cranialis, and flexor digitorum longus exhibited distinct architectural designs in both species, characterized by high PCSA (physiological cross sectional area) values and elongated fibers, crucial for gripping actions. However, the muscles responsible for controlling digits II, III, and IV displayed intermediate values for both fiber length and PCSA, but with variations observed between species, likely linked to differences in prey preferences.

Open access

New data and taxonomic changes influence our understanding of biogeographic patterns: A case study in Australian skinks

  •  26 April 2024

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Our study demonstrates that taxonomic changes and field observations in remote places can alter the biogeographic patterns evident within a group. Such changes can modify spatial patterns in alpha and beta diversity, and can have ramifications for conservation priorities that are based on small range sizes and areas of endemism.

Here comes the sun: Thermoregulatory behavior in ectotherms illuminated by light‐level geolocators

  •  22 April 2024

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Our study utilized commercially available light-level geolocating dataloggers to quantify the basking behavior of northern map turtles (Graptemys geographica) on the Kalamazoo River, Michigan, USA. We compared weekly differences in time spent aerial basking and light-level recorded between adult males (2nd and 3rd turtles from the left) and adult females (4th and 5th turtles from the left) by attaching radio transmitters and dataloggers to the rear margin of the carapace of the turtles. You can see the wire of the attached radio transmitter on the 4th turtle from the left.

Following urban predators – long‐term snow‐tracking data reveals changes in their abundance and habitat use

  •  22 April 2024

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We compared the occurrence of the red fox and the stone marten in Warsaw during three periods (1976–1978, 2005–2008, 2015–2021) using snow tracking. GLM models showed that the frequency of occurrence of tracks of these two species on transects increased over time and was explained by habitat type and distance from the city centre. The frequency of fox tracks was higher in more-natural habitats located far from the city centre, while the stone marten was recorded in a wider range of habitats from the first period and it colonised all habitat types in the subsequent periods. No relationship between the occurrence of the red fox and the stone marten was recorded.

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