Showing papers on "Flying squirrel published in 2018"

Oldest skeleton of a fossil flying squirrel casts new light on the phylogeny of the group

Abstract: Mammals can walk, hop, swim and fly; a few, like marsupial sugar gliders or colugos, can even glide. With 52 species scattered across the Northern hemisphere, flying squirrels are by far the most successful group that adopted this way of going airborne. To drift from tree to tree, these small animals pack their own ‘parachute’: a membrane draping between their lower limbs and the long cartilage rods that extend from their wrists. Tiny specialized wrist bones, which are unique to flying squirrels, help to support the cartilaginous extensions. The origin of flying squirrels is a point of contention: while most genetic studies point towards the group splitting from tree squirrels about 23 million years ago, the oldest remains – mostly cheek teeth – suggest the animals were already soaring through forests 36 million years ago. However, recent studies show that the dental features used to distinguish between gliding and non-gliding squirrels may actually be shared by the two groups. In 2002, the digging of a dump site in Barcelona unearthed a peculiar skeleton: first a tail and two thigh bones, big enough that the researchers thought it could be the fossil of a small primate. In fact, and much to the disappointment of paleoprimatologists, further excavating revealed that it was a rodent. As the specimen – nearly an entire skeleton – was being prepared, paleontologists insisted that all the ‘dirt’ attached to the bones had to be carefully screen-washed. From the mud emerged the minuscule specialized wrist bones: the primate-turned-rodent was in fact Miopetaurista neogrivensis, an extinct flying squirrel. Here, Casanovas-Vilar et al. describe the 11.6 million years old fossil, the oldest ever found. The wrist bones reveal that the animal belongs to the group of flying squirrels that have large sizes. Evolutionary analyses that combined molecular and paleontological data demonstrated that flying squirrels evolved from tree squirrels as far back as 31 to 25 million years ago, and possibly even earlier. In addition, the results show that Miopetaurista is closely related to Petaurista, a modern group of giant flying squirrels. In fact, their skeletons are so similar that the large species that currently inhabit the tropical and subtropical forests of Asia could be considered living fossils. Molecular and paleontological data are often at odds, but this fossil shows that they can be reconciled and combined to retrace history. Discovering older fossils, or even transitional forms, could help to retrace how flying squirrels took a leap from the rest of their evolutionary tree.

Predation risk landscape modifies flying and red squirrel nest site occupancy independently of habitat amount.

Abstract: Habitat choice often entails trade-offs between food availability and predation risk. Understanding the distribution of individuals in space thus requires that both habitat characteristics and predation risk are considered simultaneously. Here, we studied the nest box use of two arboreal squirrels who share preferred habitat with their main predators. Nocturnal Ural owls (Strix uralensis) decreased occurrence of night-active flying squirrels (Pteromys volans) and diurnal goshawks (Accipiter gentilis) that of day-active red squirrels (Sciurus vulgaris). Unexpectedly, the amount of preferred habitat had no effect on nest box use, but, surprisingly, both squirrel species seemed to benefit from close proximity to agricultural fields and red squirrels to urban areas. We found no evidence of trade-off between settling in a high-quality habitat and avoiding predators. However, the amount of poor-quality young pine forests was lower in occupied sites where goshawks were present, possibly indicating habitat specific predation on red squirrels. The results suggest that erecting nest boxes for Ural owls should be avoided in the vicinity of flying squirrel territories in order to conserve the near threatened flying squirrels. Our results also suggest that flying squirrels do not always need continuous old forests, and hence the currently insufficient conservation practices could be improved with reasonable increases in the areas left untouched around their nests. The results of this study demonstrate the importance of taking into account both habitat requirements and predation risk as well as their interactive effects when modeling the occupancy of threatened animal species and planning their conservation.

Effects of Temperature and Day Length on Daily Movements and Home Range of Glaucomys volans (Southern Flying Squirrel) in the Northeastern United States

Abstract: To maximize energy gained and minimize energy expended, animals should forage in a manner that gives them the largest benefit at the lowest cost. Species living in seasonal environments in the northeastern US, such as the Glaucomys volans (Southern Flying Squirrel), need to overcome high energetic demands associated with thermoregulation and food availability. In this study, we measured nightly travelled distance and home range of Southern Flying Squirrel to understand how they adapt to changes in temperature and day length. Our results showed that Southern Flying Squirrel travelled longer distances and expanded their home range in warmer temperatures and longer day-lengths. Our study contributes to our understanding of how animals adapt to constantly changing environmental conditions in the northeastern United States.

Phylogenetic position of the Siberian flying squirrel Pteromys volans based on complete mitochondrial genome sequences.

Abstract: The mitogenome of the Siberian flying squirrel Pteromys volans is a circular molecule of 16,514 bp, consisting of a control region and a conserved set of 37 genes containing 13 protein-coding genes...

Corticosteroid-binding globulin levels in North American sciurids: implications for the flying squirrel stress axis

Abstract: Corticosteroid-binding globulin (CBG) helps to regulate tissue bioavailability of circulating glucocorticoids (GCs), and in most vertebrates, ≥ 80-90% of GCs bind to this protein. New World flying squirrels have higher plasma total cortisol levels (the primary corticosteroid in sciurids) than most vertebrates. Recent research suggests that flying squirrels have either low amounts of CBG or CBG molecules that have a low binding affinity for cortisol, since this taxon appears to exhibit very low proportions of cortisol bound to CBG. To test whether CBG levels have been adjusted over evolutionary time, we assessed the levels of this protein in the plasma of northern (Glaucomys sabrinus Shaw, 1801) and southern (G. volans L., 1758) flying squirrels using immunoblotting, and compared the relative levels among three phylogenetically related species of sciurids. We also compared the pattern of CBG levels with cortisol levels for the same individuals. Flying squirrels had higher cortisol levels than the other spe...

Occurrence of the red giant flying squirrel (petaurista petaurista: Sciuridae) in Bangladesh

Abstract: This report confirms the presence of the red giant flying squirrel Petaurista petaurista from the Idgarh Reserve Forest in Cox’s Bazar (North) Forest Division in the southern part of Bangladesh. The chestnut-red dorsal body colour, white ventral surface, large and flesh-coloured nostrils, and gray long tail with blackish tip confirm the observed species as a red giant flying squirrel. Long-term monitoring, habitat protection and its ecology need to be studied for initiating further steps to conserve it in Bangladesh.