Summer diving and haul‐out behavior of leopard seals (Hydrurga leptonyx) near mesopredator breeding colonies at Livingston Island,Antarctic Peninsula

Leopard seals are conspicuous apex predators in Antarctic coastal ecosystems, yet their foraging ecology is poorly understood. Historically, the ecology of diving vertebrates has been studied using high‐resolution time‐depth records; however, to date such data have not been available for leopard seals. Twenty‐one time‐depth recorders were deployed on seasonally resident adult females in January and February between 2008 and 2014. The average deployment length was 13.65 ± 11.45 d and 40,308 postfilter dives were recorded on 229 foraging trips. Dive durations averaged 2.20 ± 1.23 min. Dives were shallow with 90.1% measuring 30 m or less, and a mean maximum dive depth of 16.60 ± 10.99 m. Four dive types were classified using a k‐means cluster analysis and compared with corresponding animal‐borne video data. Dive activity (number of dives/hour) was concentrated at night, including crepuscular periods. Haul‐out probabilities were highest near midday and were positively correlated with available daylight. Visual observations and comparisons of diving activity between and within years suggest individual‐based differences of foraging effort by time of day. Finally, dive and video data indicate that in addition to at‐surface hunting, benthic searching and facultative scavenging are important foraging strategies for leopard seals near coastal mesopredator breeding colonies.     

研究: 暗示性动作诱发的空间注意转移

暗示性动作是指个体在观看静止躯体图片时知觉到动作信息.本研究采用无预测性和反向预测性的中央线索提示范式,考察了暗示性动作和无动作线索诱发的观察者空间注意转移及两类线索诱发注意转移的方式.实验1和2采用无预测性范式,发现暗示性的扔动作能够诱发观察者的空间注意转移(实验1),且这种注意转移并不是单侧目标突现所导致的(实验2).实验3采用反向预测范式,发现暗示性动作诱发空间注意转移可能是以一种自主控制的方式进行的.此外,实验还发现仅仅观察他人的躯干朝向(站立)不足以诱发观察者注意转移.本研究进一步丰富了"注意朝向检测器"假说,暗示性动作作为一种整体性躯体线索,可能和其他局部生物线索所诱发的注意效应机制存在差异.     

Sheep deficient in vitamin E preferentially select for a feed with a higher concentration of vitamin E

Given the capacity of ruminants to modify diet selection based on metabolic needs, we hypothesised that, when given a choice, lambs experiencing a vitamin E deficiency would consume more of a vitamin E-enriched feed than lambs not deficient in vitamin E. Fifty-six Dohne Merino lambs were divided into two groups and fed either a vitamin E-deficient diet over 40 days to induce low plasma vitamin E or a vitamin E-enriched diet to induce high plasma vitamin E. The lambs were then offered a choice of vitamin E-enriched and vitamin E-deficient pellets. For half of the animals, the enriched diet was paired with strawberry flavour and the deficient diet was paired with orange flavour, while the reverse pairings were offered to the others. Lamb preference for the diets was measured daily for the following 15 days. There was a three-way interaction between the high and low vitamin E treatment groups×vitamin E content and type of flavour in the feed×time (days). The lambs preferred pellets flavoured with strawberry but this preference changed to orange flavour in vitamin E-deficient lambs if the orange flavour was paired with high vitamin E. Lambs without a deficiency continued to prefer strawberry-flavoured pellets, regardless of the vitamin E concentrations in the pellets. It is possible that self-learning contributed to the low vitamin E group of lambs changing preference to orange flavour in order to consume more vitamin E, presumably to remediate the deficiency.     

Locomotory abilities and habitat of the Cretaceous bird Gansus yumenensis inferred from limb length proportions

The relative length proportions of the three bony elements of the pelvic (femur, tibiotarsus and tarsometatarsus) and pectoral (humerus, ulna and manus) limbs of the early Cretaceous bird Gansus yumenensis, a well‐represented basal ornithuromorph from China, are investigated and compared to those of extant taxa. Ternary plots show that the pectoral limb length proportions of Gansus are most similar to Apodiformes (swifts and hummingbirds), which plot away from all other extant birds. In contrast, the pelvic limb length proportions of Gansus fall within the extant bird cluster and show similarities with the neornithine families Podicipedidae (grebes), Diomedeidae (albatross) and Phalacrocoracidae (cormorants). Although it does have some of the pelvic limb features of grebes and cormorants, the femur of Gansus is more gracile and is thus more consistent with an albatross‐like shallow‐diving mode of life than a strong foot‐propelled diving movement pattern. The position of Gansus in pectoral limb ternary morphospace is largely due to its elongated manus. In contrast to apodiformes, where the humerus and ulna are short and robust, an adaptation, which provides a stiff wing for their demanding fast agile and hovering flight (respectively), the wing‐bones of Gansus are slender, indicating a less vigorous flapping flight style. The suite of characters exhibited by Gansus mean it is difficult to completely interpret its likely ecology. Nevertheless, our analyses suggest that it is probable that this bird was both volant and capable of diving to some degree using either foot‐propelled or, perhaps, both its wings and its feet for underwater locomotion.     

Trial Implantation of Heart Rate Data Loggers in Pinnipeds

ABSTRACT Pinnipeds are major consumers in marine ecosystems, and understanding their energy budgets is essential to determining their role in food webs, particularly where there is competition with fisheries. Food consumption and energy expenditure have been evaluated in pinnipeds using different methods, but the use of heart rate to estimate energy expenditure is potentially a very powerful tool suited to the life history of these animals. We tested a procedure for the subcutaneous implantation of heart rate data loggers to determine whether heart rate could be recorded for ≥1 year in free-ranging pinnipeds, as it has been in birds. We implanted 3 captive California sea lions (Zalophus californianus) and 3 captive northern elephant seals (Mirounga angustirostris) with heart rate data loggers and monitored their recovery and behavior in a controlled environment. In both species, the implantation site allowed for excellent detection of the electrocardiogram, and we observed heart rate signatures characteristic of behaviors such as resting and diving. Although all 3 sea lions recovered well from the implantation surgery, all 3 elephant seals showed a substantial inflammatory response for unknown reasons, and we removed the implanted data loggers. Subcutaneous implantation of data loggers is a powerful technique to study physiology, energetics, and behavior in California sea lions, but more work is required to realize the potential of this technique in northern elephant seals.     

Flipper Bands Modify the Short-Term Diving Behavior of Little Penguins

ABSTRACT Flipper banding has long been the primary method to identify individual penguins, despite studies indicating that it may be detrimental to breeding success and survival. Our objectives were to measure the effects that flipper bands may have on diving performance of little penguins to determine whether the bands may be detrimental. We studied short- and long-term direct effects of flipper banding on diving behavior of free-ranging little penguins (Eudyptula minor) by comparing diving behavior before and after banding and by comparing diving performance of unbanded birds to those that had carried flipper bands for several years, respectively. Recently banded birds displayed increases in multiple variables following banding. Long-term banded penguins did not exhibit differences to their unbanded counterparts in most variables examined. Our findings are useful to those considering or reviewing the use of bands in penguin study and management.     

PHYLOGENY AND FORELIMB DISPARITY IN WATERBIRDS

Previous work has shown that the relative proportions of wing components (i.e., humerus, ulna, carpometacarpus) in birds are related to function and ecology, but these have rarely been investigated in a phylogenetic context. Waterbirds including “Pelecaniformes,” Ciconiiformes, Procellariiformes, Sphenisciformes, and Gaviiformes form a highly supported clade and developed a great diversity of wing forms and foraging ecologies. In this study, forelimb disparity in the waterbird clade was assessed in a phylogenetic context. Phylogenetic signal was assessed via Pagel's lambda, Blomberg's K, and permutation tests. We find that different waterbird clades are clearly separated based on forelimb component proportions, which are significantly correlated with phylogeny but not with flight style. Most of the traditional contents of “Pelecaniformes” (e.g., pelicans, cormorants, and boobies) cluster with Ciconiiformes (herons and storks) and occupy a reduced morphospace. These taxa are closely related phylogenetically but exhibit a wide range of ecologies and flight styles. Procellariiformes (e.g., petrels, albatross, and shearwaters) occupy a wide range of morphospace, characterized primarily by variation in the relative length of carpometacarpus and ulna. Gaviiformes (loons) surprisingly occupy a wing morphospace closest to diving petrels and penguins. Whether this result may reflect wing proportions plesiomorphic for the waterbird clade or a functional signal is unclear. A Bayesian approach detecting significant rate shifts across phylogeny recovered two such shifts. At the base of the two sister clades Sphenisciformes + Procellariiformes, a shift to an increase evolutionary rate of change is inferred for the ulna and carpometacarpus. Thus, changes in wing shape begin prior to the loss of flight in the wing‐propelled diving clade. Several shifts to slower rate of change are recovered within stem penguins.     

Influence of structure on the tissue dynamics of the human soleus muscle observed in MRI studies during isometric contractions

This article investigates how the internal structure of muscle and its relationship with tendon and even skeletal structures influence the translation of muscle fiber contractions into movement of a limb. Reconstructions of the anatomy of the human soleus muscle from the Visible Human Dataset (available from the National Library of Medicine), magnetic resonance images (MRI), and cadaver studies revealed a complex 3D connective tissue structure populated with pennate muscle fibers. The posterior aponeurosis and the median septum of the soleus form the insertion of the muscle and are continuous with the Achilles tendon. The distal extremities of the pennate muscle fibers attach to these structures. The anterior aponeurosis is located intramuscularly, between the posterior aponeurosis and the median septum. It forms the origin of the muscle and contacts the proximal extremities of the soleus muscle fibers. MRI measurements of in vivo tissue velocities during isometric contractions (20% and 40% maximum voluntary contractions) revealed a similarly complex 3D distribution of tissue movements. The distribution of velocities was similar to the distribution of major connective tissue structures within the muscle. During an isometric contraction, muscle fiber contractions move the median septum and posterior aponeurosis proximally, relative to the anterior aponeurosis. The pennate arrangement of muscle fibers probably amplifies muscle fiber length changes but not sufficiently to account for the twofold difference in muscle fiber length changes relative to excursion of the calcaneus. The discrepancy may be accounted for by an additional gain mechanism operating directly on the Achilles tendon by constraining the posterior movement of the tendon, which would otherwise occur due to the increasingly posterior location of the calcaneus in plantarflexeion.     

Acute effects of eccentric work on a bicycle ergometer

Dynamics of the delayed-onset muscle soreness after the exercise on a bicycle ergometer with floating seat under predominantly concentric and eccentric conditions was evaluated using three different tests. Depending on the used test, the maximum delayed-onset muscle soreness was recorded on days 1 to 3 after the exercise without significant differences between the groups performing concentric and eccentric work. A trend of a slower development of both the delayed onset of muscle soreness and the corresponding recovery was recorded by the test with a passive pressure on the working muscle group (knee joint extensor muscles). A positive correlation between the delayed-onset muscle soreness and the relative work intensity was found; the relative intensity was assessed according to the decrease in strength during the recovery period. No correlation between the delayed-onset muscle soreness and exercise duration was detected.