ESTIMATING PUP PRODUCTION OF HARP SEALS, PAGOPHILUS GROENLANDICUS, IN THE NORTHWEST ATLANTIC

Photographic and visual aerial surveys to determine current pup production of Northwest Atlantic harp seals were conducted off Newfoundland and in the Gulf of St. Lawrence during March 1999-Photographic surveys were conducted on all whelping concentrations between 14 and 24 March, whereas a visual survey was made of the southern Gulf concentrations on 14 March. Pup production was estimated to be 739,100 (SE = 96,300, CV = 13.0%) at the Front, 82,600 (SE = 22,500, CV = 27.2%) in the northern Gulf, and 176,200 (SE = 25,400, CV = 14.4%) in the southern Gulf (Magdalen Island) for a total of 997,900 (SE = 102,100, 10.2%). Changes in aerial survey estimates indicate that pup production has increased since 1994. A new method to correct for the temporal change in the proportion of pups present on the ice was examined by fitting the percentage of pups observed in three age-dependent stages to a Normal distribution. The results were compared to those obtained from a more complex model used previously. The Simple model produced slightly higher, and hence more conservative, estimates of the proportion of births that had occurred before the time of the survey than the Complex model. When using the Simple model fewer assumptions regarding the start date of pupping and the proportion of older pups remaining on the ice were required, the herd had to be followed for a shorter period, and a more convenient means of calculating confidence limits was available.     

Male‐specific alterations in structure of isolation call sequences of mouse pups with 16p11.2 deletion

16p11.2 deletion is one of the most common gene copy variations that increases the susceptibility to autism and other neurodevelopmental disorders. This syndrome leads to developmental delays, including speech impairment and delays in expressive language and communication skills. To study developmental impairment of vocal communication associated with 16p11.2 deletion syndrome, we used the 16p11.2del mouse model and performed an analysis of pup isolation calls (PICs). The earliest PICs at postnatal day 5 from 16p11.2del pups were found altered in a male‐specific fashion relative to wild‐type (WT) pups. Analysis of sequences of ultrasonic vocalizations (USVs) emitted by pups using mutual information between syllables at different positions in the USV spectrograms showed that dependencies exist between syllables in WT mice of both sexes. The order of syllables was not random; syllables were emitted in an ordered fashion. The structure observed in the WT pups was identified and the pattern of syllable sequences was considered typical for the mouse line. However, typical patterns were totally absent in the 16p11.2del male pups, showing on average random syllable sequences, while the 16p11.2del female pups had dependencies similar to the WT pups. Thus, we found that PICs were reduced in number in male 16p11.2 pups and their vocalizations lack the syllable sequence order emitted by WT males and females and 16p11.2 females. Therefore, our study is the first to reveal sex‐specific perinatal communication impairment in a mouse model of 16p11.2 deletion and applies a novel, more granular method of analysing the structure of USVs.     

Developmental emergence of fear/threat learning: neurobiology,associations and timing

Pavlovian fear or threat conditioning, where a neutral stimulus takes on aversive properties through pairing with an aversive stimulus, has been an important tool for exploring the neurobiology of learning. In the past decades, this neurobehavioral approach has been expanded to include the developing infant. Indeed, protracted postnatal brain development permits the exploration of how incorporating the amygdala, prefrontal cortex and hippocampus into this learning system impacts the acquisition and expression of aversive conditioning. Here, we review the developmental trajectory of these key brain areas involved in aversive conditioning and relate it to pups' transition to independence through weaning. Overall, the data suggests that adult‐like features of threat learning emerge as the relevant brain areas become incorporated into this learning. Specifically, the developmental emergence of the amygdala permits cue learning and the emergence of the hippocampus permits context learning. We also describe unique features of learning in early life that block threat learning and enhance interaction with the mother or exploration of the environment. Finally, we describe the development of a sense of time within this learning and its involvement in creating associations. Together these data suggest that the development of threat learning is a useful tool for dissecting adult‐like functioning of brain circuits, as well as providing unique insights into ecologically relevant developmental changes.     

Evidence for non-genomic transmission of ecological information via maternal behavior in female rats

Maternal behavior is flexible and programs offspring development. Using a novel manipulation, we demonstrate that rat maternal behavior is sensitive to ecologically relevant stimuli. Long-Evans hooded rat dams (F0) and pups were exposed to a predator condition (cat odor) or a control condition (no odor) for 1 h on the day of parturition. Predator-exposed F0 dams displayed significantly more maternal behavior (licking/grooming, arched-back nursing) relative to control-exposed dams across five subsequent observation days. Female offspring (F1) were raised to adulthood, bred and maternal behavior was observed. F1 dams reared by a predator-exposed F0 dam displayed significantly higher maternal behavior relative to F1 dams reared by a control-exposed F0 dam across 5 days of observation. Increased levels of maternal behavior in predator-reared (PR) F1 dams were evident even in F1 females that had been cross-fostered (CF) from a control-exposed F0 dam, suggesting a non-genomic transmission of increased levels of maternal behavior. Lactating PR F1 dams had significantly elevated estrogen receptor alpha and beta mRNA in the medial preoptic area relative to control-reared (CR) F1 dams. Furthermore, among CR F1 dams, there was no significant difference between those dams that had been CF from predator-exposed F0 dams and those that had been sham CF. These results support the hypothesis that flexible rat maternal behavior can shape offspring development according to current environmental conditions. The results also suggest that estrogen signaling may be part of an epigenetic mechanism by which changes in maternal behavior are passed from F0 to F1 dams.     

Individual variation in pup vocalizations and absence of behavioral signs of maternal vocal recognition in Weddell seals (Leptonychotes weddellii)

Individually stereotyped vocalizations often play an important role in relocation of offspring in gregarious breeders. In phocids, mothers often alternate between foraging at sea and attending their pup. Pup calls are individually distinctive in various phocid species. However, experimental evidence for maternal recognition is rare. In this study, we recorded Weddell seal (Leptonychotes weddellii) pup vocalizations at two whelping patches in Atka Bay, Antarctica, and explored individual vocal variation based on eight vocal parameters. Overall, 58% of calls were correctly classified according to individual. For males (n= 12) and females (n= 9), respectively, nine and seven individuals were correctly identified based on vocal parameters. To investigate whether mothers respond differently to calls of familiar vs. unfamiliar pups, we conducted playback experiments with 21 mothers. Maternal responses did not differ between playbacks of own, familiar, and unfamiliar pup calls. We suggest that Weddell seal pup calls may need to contain only a critical amount of individually distinct information because mothers and pups use a combination of sensory modalities for identification. However, it cannot be excluded that pup developmental factors and differing environmental factors between colonies affect pup acoustic behavior and the role of acoustic cues in the relocation process.     

COUNTING STELLER SEA LION PUPS IN ALASKA: AN EVALUATION OF MEDIUMFORMAT, COLOR AERIAL PHOTOGRAPHY

Estimates of Steller sea lion ( Eumetopias jubatus ) pup production are valuable for estimating population trend and size. Currently in Alaska, pups are counted by visiting rookeries, driving older animals into the water, then walking through the rookeries and counting the pups, a highly disruptive procedure. At smaller rookeries, with good vantage points, pups are occasionally counted from the periphery of rookeries without disturbing the sea lions. We evaluated counts made from medium-format, color, aerial photographs as an alternative to drive counts and peripheral counts. Neither the peripheral counts nor the aerial photographic counts disturbed animals on the rokeries. There were strong 1:1 linear relationships between photographic counts and drive counts ( r ²= 0.966, P < 0.001) and between photographic counts and peripheral counts ( r ²= 0.999, P < 0.001). Precision was similar for all three methods of counting. We suggest that medium-format, color, aerial photographs is appropriate for routine surveys of Steller sea lion pups in Alaska because it is not disruptive to the hauled-out sea lions and provides comparable estimates with similar precision to drive and peripheral counts. Large areas canbe rapidly surveyed during periods of good weather with a minimum of manpower.     

Den shifting by wolves in semi-wild landscapes in the Deccan Plateau, Maharashtra, India

Reproductive success is crucial for the survival and persistence of any species. The Deccan Biogeographic Zone of India is the stronghold of a population of the Indian wolf Canis lupus pallipes . Gaining a better understanding of the den-use pattern of wolves in different areas in this zone is thus vital for their conservation and management. The wolves excavated multiple dens in our study sites and kept shifting their litters among them. Major disturbance factors around denning sites were active stone quarries, traffic, crop harvesting and livestock movement. One wolf pack used 14 dens in four breeding seasons. Discriminant function analysis indicated that den shifting by wolves was not entirely governed by disturbance levels at den sites. Increasing age of pups was one of the main factors associated with den shifting rather than the magnitude of disturbance ( χ ²=34.26, d.f.=12, P <0.001). Tolerance to disturbance around dens during the early stages of pup development was negatively correlated ( r =−0.519, P <0.05) with availability of water and age of pups ( r =−0.613, P <0.01). Excavation of multiple dens by wolves was apparently related to den shifting, which seemingly is a survival strategy of wolves in these semi-wild human-dominated landscapes in the Deccan Biogeographic Zone. Principal components analysis indicated that during the initial stages of pup development, nature of the land, den orientation and distance of the den from roads were important cues in addition to age category of pups for den shifting. The analysis also suggested that factors such as distance of the new den where pups are to be transferred, distance from water source and availability of fox Vulpes bengalensis holes for den use were also important.     

DISTRIBUTION AND POPULATION SIZE OF THE SOUTHERN SEA LION (OTARIA FLAVESCENS) IN CENTRAL AND SOUTHERN CHUBUT,PATAGONIA, ARGENTINA

Population size and distribution of Otaria flavescens in central and southern Chubut, Patagonia were determined by aerial censuses conducted during the breeding season in 1989 and 1995 and outside the season. Pup numbers were corrected by means of a linear regression between pup and adult male (AM) numbers obtained from terrestrial censuses carried out in 1994 and 1996. During the 1989 breeding season, 10,557 sea lions occurred at 29 locations; 2,800 (26.3%) were pups. During the 1995 breeding season, 14,887 animals were censused at 32 sites; 3,311 (22.2%) were pups. The corrected pup number increased to 4,852, indicating that around 32% is lost when counting from photographs. The corrected total number increased to 16,483; this fell to less than one half between breeding seasons (November 1990 and 1995). The 1995 breeding season census represents the highest number since 1972 (8,800) and the widest historical dispersion (37 sites year round contrasting with 13 in the late 1940s and 1972). However, the present number is about one half of the 33,000 censused about 50 yr ago. Using a correction factor developed for the north Paragonian population (1.8 × censused number) the present population size in the area can be estimated at around 29,669 individuals.     

The role of olfactory cues in mother–pup,groupmate, and sex recognition of lesser flat‐headed bats,Tylonycteris pachypus

Tylonycteris pachypus is a gregarious bat species with tens of individuals in a colony. The mechanisms by which mother bats recognize their pups and adult bats recognize each other are not clear. We hypothesized that such recognition is achieved by chemical discrimination and performed experiments to test the hypothesis. Results showed that mother bats were much more attracted to the scent from their own pups. For adult bats, females were attracted to the scent from both male and female groupmates but had a higher preference to the scent from female than from male groupmates. Male bats were much more attracted to the scent from male groupmates while showed no preference to the scent from female groupmates. Within a group, both female and male bats had no difference in preference to the scent from the same or opposite sex. These results suggest that mother–pup and groupmate recognition of T. pachypus can be achieved by olfactory cues.     

Brain serotonin determines maternal behavior and offspring survival

Maternal care is an indispensable component of offspring survival and development in all mammals and necessary for reproductive success. Although brain areas regulating maternal behaviors are innervated by serotonergic afferents, very little is known about the role of this neurotransmitter in these behaviors. To evaluate the contribution of serotonin to maternal care, we used mice with a null mutation in the gene for tryptophan hydroxylase‐2 (TPH2), which results in a genetic depletion of brain serotonin, and tested them in a wide range of maternal behavior paradigms. We found that litters born to and reared by TPH2^?/? mothers showed decreased survival, lower weaning weights and increased cannibalization. In addition, TPH2^?/? mothers performed poorly in pup retrieval, huddling, nest construction and high‐arched back nursing. Aggression in TPH2^?/? dams was not triggered by lactation and was steadily high. Survival and weaning weight deficits of TPH2^?/? pups were rescued by cross‐fostering and in litters of mixed genotype (TPH2^?/? and TPH2^?/+). However, the maternal behaviors of TPH2^?/? dams did not improve when rearing either TPH2^+/+ pups or mixed‐genotype litters. In addition, TPH2^?/? pups significantly worsened the behavior of TPH2^+/+ dams with respect to cannibalism, weaning weight and latency to attack. Olfactory and auditory functions of TPH2^?/? females or anxiety‐like behaviors did not account for these maternal alterations as they were equal to their TPH2^+/+ counterparts. These findings illustrate a profound influence of brain serotonin on virtually all elements of maternal behavior and establish that TPH2^?/? pups can engender maladaptive mothering in dams of both genotypes.