REDUCED POPULATION GROWTH OF GRAY SEALS AT SABLE ISLAND: EVIDENCE FROM PUP PRODUCTION AND AGE OF PRIMIPARITY

Pup production on Sable Island, Nova Scotia, has been increasing exponentially since the early 1960s and by 1997 Sable Island was the largest gray seal colony worldwide. Using an aerial photographic survey, as in previous years, we estimated pup production in January 2004 to determine if this exponential rate of increase had continued. A total of 33,268 pups was counted on the color positives. When corrected for the proportion pups missed on the imagery (1.106 for the 12th; 1.527 on the 13th), the proportion of pups that died prior to the survey (0.031), and the proportion of pups born before the survey (east colony 0.966, west colony 0.962), estimated total pup production was 41,500 with SE = 4,381. The 2004 estimate indicates that pup production on Sable Island has continued to increase, but suggests that the rate of increase ( r ) may have declined (0.070 compared to previous 0.128). Females from the 1998–2000 cohorts were about 16 times less likely to give birth for the first time at age 4 yr and more than twice as likely at age 6 yr compared to those in the mid-late 1980s. The new estimate of pup production and observed changes in age of primiparity provide the first indication of changes in vital rates of this population. However, additional estimates of pup production and vital rates are needed to confirm this conclusion and to investigate the underlying mechanisms.     

Factors influencing and consequences of breeding dispersal and habitat choice in female grey seals (<Emphasis Type="Italic">Halichoerus grypus</Emphasis>) on Sable Island,Nova Scotia

Selection of breeding location can influence reproductive success and fitness. Breeding dispersal links habitat use and reproduction. This study investigated factors affecting breeding dispersal and its reproductive consequences in grey seals (Halichoerus grypus) on Sable Island, Nova Scotia. Breeding dispersal distance was determined in 692 individually marked, known-age female grey seals observed from 2004 to 2014. We used generalized linear mixed-effects models to test hypotheses concerning environmental and demographic factors influencing breeding dispersal distance and the consequences of dispersal distance on offspring weaning mass. Grey seal females rarely exhibited fidelity to previous breeding sites. Median dispersal distance between years was 5.1 km. Only 2.9% of females returned to a previous breeding site. Breeding dispersal distance was affected by parity and density, but effects were small and are presumably of no biological significance. Variation in dispersal distance among adult females was large. Dispersal distance had no significant influence on offspring weaning mass; however, as previously found, pup sex and maternal age did. Although breeding location was not important, heavier pups were born in habitats with no tidal or storm-surge influence indicating that breeding habitat type did influence offspring size at weaning. The lack of site fidelity in grey seals on Sable Island is associated with an unpredictable and changing landscape (sand dunes) that could make it difficult for females to locate previous breeding locations. Although breeding location within habitat type had small consequences on offspring weaning mass, we detected no evidence that breeding site selection within the habitat had consequences to females.     

Male mating success in an aquatically mating pinniped, the harbour seal (Phoca vitulina), assessed by microsatellite DNA markers

Similar to many other pinniped species, harbour seals ( Phoca vitulina ) mate exclusively at sea. Here we present the first attempt to measure male mating success in an aquatically mating pinniped. Male mating success was estimated by paternity analysis in two cohorts of pups born at Sable Island, Nova Scotia, Canada, using microsatellite DNA markers. The genotypes of 275 pups born in 1994 and 1995 were compared to those of 90 candidate males at six microsatellite loci using a likelihood approach to resolve paternity. Paternity could be assigned for two, 22, 40 and 85 pups at confidence levels of 95, 80, 65 and 50%, respectively. Most successful males were assigned the paternity of a single offspring, suggesting a low variance in male mating success relative to most pinniped species. The proportion of paternal half sibs within cohorts and between maternally related sibs estimated by maximum likelihood were not significantly different from zero. It is thus unlikely that most offspring were sired by a small number of highly successful unsampled males, and that female harbour seals do not usually exhibit fidelity to the same male in sequential breeding seasons. A low level of polygyny in Sable Island harbour seals is consistent with predictions based on their breeding ecology, as females are highly mobile and widely dispersed in the aquatic mating environment at Sable Island.     

Migratory movements and wintering areas of Leach's Storm‐Petrels tracked using geolocators

Accumulating evidence suggests that Atlantic populations of Leach's Storm‐Petrels (Oceanodroma leucorhoa) are experiencing significant declines. To better understand possible causes of these declines, we used geolocators to document movements of these small (～50‐g) pelagic seabirds during migration and the non‐breeding period. During 2012 and 2013, movement tracks were obtained from two birds that traveled in a clock‐wise direction from two breeding colonies in eastern Canada (Bon Portage Island, Nova Scotia, and Gull Island, Newfoundland) to winter in tropical waters. The bird from Bon Portage Island started its migration towards Cape Verde in October, arrived at its wintering area off the coast of eastern Brazil in January, and started migration back to Nova Scotia in April. The bird from Gull Island staged off Newfoundland in November and then again off Cape Verde in January before its geolocator stopped working. Movements of Leach's Storm‐Petrels in our study and those of several other procellariiforms during the non‐breeding period are likely facilitated by the prevailing easterly trade winds and the Antilles and Gulf Stream currents. Although staging and wintering areas used by Leach's Storm‐Petrels in our study were characterized by low productivity, the West Africa and northeastern Brazilian waters are actively used by fisheries and discards can attract Leach's Storm‐Petrels. Our results provide an initial step towards understanding movements of Leach's Storm‐Petrels during the non‐breeding period, but further tracking is required to confirm generality of their migratory routes, staging areas, and wintering ranges.     

Pup Shoving by Adult Naked Mole-Rats

Adult naked mole‐rats (Heterocephalus glaber) characteristically perform an unusual behavior toward young: they shove small pups frequently and vigorously around the nest. We studied 15 litters in five captive colonies to quantify which adults shove pups, changes in shoving frequencies as pups develop, how external disturbances affect pup‐shoving frequencies, and behavior of juveniles that were not shoved as pups. In all litters and colonies the breeding female shoved pups significantly more often than any other individual. Breeding females also shoved adult colony mates, but at far lower rates than they shoved pups. Breeding males shoved pups about half as often as did breeding females. Together, the parents shoved pups ten times more often than did nonbreeders. Frequencies of pup shoving peaked when pups were 3–4 wk old, roughly coincident with weaning. When colonies were disturbed experimentally, frequencies of pup shoving increased dramatically, whereas rates at which nonbreeding adults were shoved decreased sharply. We separated four newly‐weaned litters and raised half the pups apart from their colony. When these litters were reunited 4–9 wk later, the unshoved (experimental) pups were the same size as the frequently shoved (control) pups, but the unshoved pups were significantly less likely to flee from a disturbance. Shoving of small pups encourages them to flee from danger, and also may enforce weaning.     

PUP PRODUCTION AND POPULATION TRENDS OF THE AUSTRALIAN FUR SEAL (ARCTOCEPHALUS PUSILLUS DORIFERUS)

We estimated the number of live Australian fur seal pups using capture-markresights, direct ground counts, or aerial photography at all breeding sites following the pupping season of November-December 2002. Pups were recorded at 17 locations; nine previously known colony sites, one newly recognized colony and seven haul-out sites where pups are occasionally born. In order of size, the colonies were Lady Julia Percy Island (5,899 pups), Seal Rocks (4,882), The Skerries (2,486), Judgment Rocks (2,427), Kanowna Island (2,301), Moriarty Rocks (1,007), Reid Rocks (384), West Moncoeur Island (257), and Tenth Island (124). The newly recognized site was Rag Island, in the Cliffy Group, where we recorded 30 pups. We also recorded pups at the following haul-out sites: Cape Bridge-water (7 pups), Bull Rock (7), Wright Rock (5), Twin Islet (1), The Friars (1), He des Phoques (1), and Montague Island (1). In total, we estimate there were 19,819 (SE = 163) live pups at the time of the counts. We discuss trends in pup numbers and derive current population estimates for the Australian fur seal.     

Behavioral signature of intraspecific competition and density dependence in colony‐breeding marine predators

In populations of colony‐breeding marine animals, foraging around colonies can lead to intraspecific competition. This competition affects individual foraging behavior and can cause density‐dependent population growth. Where behavioral data are available, it may be possible to infer the mechanism of intraspecific competition. If these mechanics are understood, they can be used to predict the population‐level functional response resulting from the competition. Using satellite relocation and dive data, we studied the use of space and foraging behavior of juvenile and adult gray seals (Halichoerus grypus) from a large (over 200,000) and growing population breeding at Sable Island, Nova Scotia (44.0 ^oN 60.0 ^oW). These data were first analyzed using a behaviorally switching state‐space model to infer foraging areas followed by randomization analysis of foraging region overlap of competing age classes. Patterns of habitat use and behavioral time budgets indicate that young‐of‐year juveniles (YOY) were likely displaced from foraging areas near (<10 km) the breeding colony by adult females. This displacement was most pronounced in the summer. Additionally, our data suggest that YOY are less capable divers than adults and this limits the habitat available to them. However, other segregating mechanisms cannot be ruled out, and we discuss several alternate hypotheses. Mark–resight data indicate juveniles born between 1998 and 2002 have much reduced survivorship compared with cohorts born in the late 1980s, while adult survivorship has remained steady. Combined with behavioral observations, our data suggest YOY are losing an intraspecific competition between adults and juveniles, resulting in the currently observed decelerating logistic population growth. Competition theory predicts that intraspecific competition resulting in a clear losing competitor should cause compensatory population regulation. This functional response produces a smooth logistic growth curve as carrying capacity is approached, and is consistent with census data collected from this population over the past 50 years. The competitive mechanism causing compensatory regulation likely stems from the capital‐breeding life‐history strategy employed by gray seals. This strategy decouples reproductive success from resources available around breeding colonies and prevents females from competing with each other while young are dependent.     

Diets of northern fulmar (<Emphasis Type="Italic">Fulmarus glacialis</Emphasis>) chicks in the northwest Atlantic Ocean

Northern fulmars (Fulmarus glacialis) have recently expanded their breeding range in the northwest Atlantic Ocean. We studied their diet in their largest colony in the northwest Atlantic on Funk Island, eastern Canada, by collecting dietary samples from chicks during 1999 and 2000. Fish, primarily capelin (Mallotus villosus), and offal from commercial fisheries were the most common foods in the diets of fulmar chicks. Crustaceans were also common prey fed to the chicks. Squids (Gonatus fabricii) were an important food in 2000. Chick diets varied considerably between the 2 years of the study. The diets of northern fulmar chicks on Funk Island were opportunistic and similar to those of chicks at other colonies in the eastern and northern North Atlantic Ocean. Compared to other regions in the North Atlantic Ocean, the diet of birds on Funk Island seems to be most similar to those from Iceland, and least resemble those from Shetland. Long-term studies of the feeding ecology on northern fulmars may be helpful in discerning factors influencing changes in the species distribution and abundance.     

Causes of mortality in South American fur seal pups (Arctophoca australis gracilis) at Guafo Island,southern Chile (2004–2008)

As part of population dynamics studies of the South American fur seal (Arctophoca australis gracilis) rookery at Punta Weather in Guafo Island (43°36'S, 74°43’W), the causes and extent of pup mortality were monitored. During four breeding seasons, daily counts of live and dead pups were carried out to determine pup production and pup mortality. Dead pups were retrieved from the rookery to perform necropsies. The mean pup production was 1,735.5 ± 336 pups and the mean pup mortality up to 12 wk old was 6.0%± 2.6%. The major causes of death were enteritis with microscopic lesions of bacteremia (28.4%), starvation (23.5%), drowning (21%), trauma (19.8%), and stillbirths (2.5%). Enteritis with microscopic lesions of bacteremia, and starvation had higher incidence during January (beginning and middle of the breeding season) while most trauma and drowning occurred during February (end of the breeding season). In the 2006–2007 breeding season there was an increase in mortality due to starvation and trauma. Most pup deaths at Guafo Island are generated by extrinsic factors; therefore, additional studies that assess the impact of environmental changes and fishing activities, are needed in order to determine the exact causes of the decline of this species along Chilean coasts.     

Distribution, abundance and breeding cycle of the Australian sea lion Neophoca cinerea (Mammalia: Pinnipedia)

Surveys of the Australian sea lion Neophoca cinerea were conducted throughout its range in Western and South Australia between December 1987 and February 1992. Almost every island was visited between Houtman Abrolhos and The Pages ( n = 255), many of them more than once.
Sea lions breed on at least 50 islands, 27 in Western Australia and 23 in South Australia. Of the 50 breeding sites, 31 have not been reported previously. A further 19 islands may also support breeding colonies. A total of 1,941 pups was counted and pup production was estimated at 2,432. Only five colonies produced more than 100 pups each and they accounted for almost half of the pup production. Most of these colonies are near Kangaroo Island, South Australia. A breeding cycle of 17–18 months has been reported for N. cinerea at Kangaroo Island and on the west coast of Western Australia; this was also noted at another 11 islands where repeated visits coincided with breeding. No evidence was found for breeding seasons shorter or longer than 17–18 months. The breeding season was not synchronized between islands, as it is in other pinnipeds. A predictive model is developed to estimate the population size from pup production figures. It indicates that pup numbers should be multiplied by between 3.81 and 4.81 to estimate the total population size just before the pupping season begins. This leads to estimates of 9,300–11,700 for the total population, considerably greater than earlier estimates.
Causes of the unique reproductive cycle of N. cinerea are unknown, but we hypothesize that it results from living in a temperate climate in some of the most biologically depauperate waters of the world. It is also clear that day length and water temperature cannot act as exogenous cues for implantation of the blastocyst; the physiological events of gestation must, rather, be cued endogenously.     

Distribution, pup production and mortality of New Zealand sea lion

Surveys were undertaken at Campbell Island / Motu Ihupuku during January and February 2008, to determine the distribution and pup production of New Zealand sea lions (NZ sea lion; Phocarctos hookeri). In addition, necropsies were performed at the main breeding site of Davis Point to determine the principal causes of early mortality for NZ sea lion pups. In total, 397 pups were tagged and 186 untagged pups were found dead, giving a minimum pup production of 583 pups and a one month of age mortality estimate of 40%. This represents a higher pup production than previous estimates from Campbell Island (although survey techniques are not comparable), and equates to 21% of the total pup production for NZ sea lions in the 2007/08 season. Early pup mortality was high (40%) at Campbell Island, with trauma, starvation, and drowning in rock pools and peat mires the major causes of death. Pups were concentrated in two colonial breeding sites: Davis Point on the north shore of Perseverance Harbour (76%) and a newly recorded breeding site (Paradise Point) on the southern shore of Perseverance Harbour (21%). Non-colonial breeding or single pups occurred around the southern parts of the island from sea level to 400 m; however, these only contributed 3% of the known pup production.     

Consequences of foraging trip duration on provisioning behaviour and fledging condition of common murres Uria aalgae

We examine the provisioning constraints of a pursuit‐diving seabird in a cold ocean regime by comparing the behaviour of common murres Uria aalge rearing chicks at two colonies in the Northwest Atlantic during 1998‐2000. Funk Island is the largest (340,000–400,000 breeding pairs) and most offshore (60 km) colony of common murres in eastern Canada. Seventy‐five percent of the Northwest Atlantic population of common murres breeds on this island. Great Island is one island within the Witless Bay Ecological Reserve, which is the second largest breeding aggregation (100 000 breeding pairs) and is located near‐shore (2 km). The primary forage fish species in Newfoundland waters is capelin Mallotus villosus, which spawns on or near coastal beaches during summer. Therefore, the two study colonies differ in their distance to food resources and colony size. It is within this natural context that we compare: (1) prey types and frequency of delivery (amount of prey), (2) parental time budgets, and (3) the mass and condition (mass/wing length) of fledglings at both colonies. Similarly sized female capelin (100–150 mm) were delivered to chicks at both colonies. Foraging time per day per parent, a proxy of foraging effort, was similar at both colonies (Great Island: 5.1 h; Funk Island: 5.5 h), as was the percentage of time spent with mates (Great Island: 12.3%; Funk Island: 10.9%). Foraging trips, however, were longer at Funk Island (4.1 h) than at Great Island (2.9 h). This resulted in lower feeding rates of chicks (0.17 feeds per h) and poorer condition of fledglings (2.9 g/mm) at Funk Island compared to those at Great Island (0.22 feeds per h; 3.9 g/mm). We hypothesize that provisioning efforts are constrained at Funk Island by (1) distant food resources and increased competitor density, resulting in longer foraging trip durations and (2) the time spent paired with mates at the colony, which may reflect a minimum time required to maintain breeding sites due to higher breeding densities at Funk Island compared to Great Island. Demographic consequences of this poor fledgling condition at Funk Island are unknown, but fledglings may sufficiently accelerate growth at sea due to their closer proximity to an important nursery area. If fledgling survival is compromised, however, the lower potential for growth at Funk Island will impact the entire Northwest Atlantic population of common murres.     

Trends in abundance of rocky intertidal seaweeds and filter feeders across gradients of elevation,wave exposure,and ice scour in eastern Canada

On NW Atlantic rocky shores, the main basal organisms in intertidal communities are seaweeds (Ascophyllum nodosum, Fucus spp. and Chondrus crispus) and filter feeders (barnacles, Semibalanus balanoides, and mussels, Mytilus spp.). Their ecology has been extensively studied in New England (United States), but knowledge gaps exist for northern shores, which are subjected to stronger environmental stress. Therefore, we studied the above organisms on Canadian shores. We quantified the summer abundance of these seaweeds and filter feeders across full vertical (intertidal elevation) and horizontal (wave exposure and winter ice scour) environmental gradients on the Gulf of St. Lawrence and open Atlantic coasts of Nova Scotia. At the regional scale along the open Atlantic coast, seaweeds showed similar abundances in Nova Scotia than values reported for New England. However, both filter feeders were considerably less abundant in Nova Scotia. At the local scale in Nova Scotia, intense winter ice scour (which only occurs on the Gulf of St. Lawrence coast) was associated with a very low abundance of all species except barnacles. Spatial trends in Nova Scotia were similar to patterns known for certain species elsewhere, such as A. nodosum being almost restricted to sheltered habitats, regardless of elevation, and C. crispus being almost restricted to low elevations, regardless of exposure. Other trends were, however, characteristic of Nova Scotia, such as C. crispus being frequent at low elevations in exposed habitats, unlike in New England, where mussels often predominate there because of competitive advantages. In Nova Scotia, mussels were always restricted to cracks and crevices, unlike in New England, where they form extensive intertidal beds on exposed shores. The direct effects of increased environmental stress and indirect effects through altered interspecific interactions might explain the regional differences in local species distribution, which will require experimental validation. Handling editor: K. Martens     

Female distribution, genetic relatedness, and fostering behaviour in harbour seals, Phoca vitulina

Although harbour seals may not recognize their relatives, relatives could be chosen preferentially for fostering (i.e. kin selection) if harbour seals display natal philopatry coupled with breeding site fidelity, and thus kin are clustered within the colony. We used behavioural and genetic data to investigate population structure within the Sable Island breeding colony and to test whether harbour seals tend to foster related pups. Adult females on Sable Island showed a high level of breeding-colony site fidelity but low levels of within-colony site fidelity both within and between years. Similarly, although lactating females showed a clumped distribution, group composition was highly variable, suggesting that this study colony was not composed of groups of related animals. DNA fingerprint data supported the hypothesis that female distribution within the colony was not correlated with genetic relatedness. Furthermore, the mean DNA band sharing among foster dyads did not differ significantly from that for unrelated animals. These results indicate that among harbour seals, related pups are not usually chosen preferentially for fostering and hence, kin selection is not likely to be influencing the occurrence of this behaviour. Copyright 1999 The Association for the Study of Animal Behaviour.     

Genetic diversity in a feral horse population from Sable Island, Canada

The present-day Sable Island horse population, inhabiting an island off the eastern coast of Canada, is believed to have originated mainly from horses confiscated from the early French settlers in Nova Scotia in the latter half of the 18th century. In 1960, the Sable Island horses were given legal protected status and no human interference has since been allowed. The objective of this study was to characterize the current genetic diversity in Sable Island horses in comparison to 15 other horse breeds commonly found in Canada and 5 Spanish breeds. A total of 145 alleles from 12 microsatellite loci were detected in 1093 horses and 40 donkeys. The average number of alleles per locus ranged from 4.67 in the Sable Island horse population to 8.25 in Appaloosas, whereas the mean observed heterozygosity ranged from 0.626 in the Sable Island population to 0.787 in Asturcons. Various genetic distance estimates and clustering methods did not permit to support that the Sable Island horses originated from shipwrecked Spanish horses, according to a popular anecdote, but closely resemble light draft and multipurpose breeds commonly found in eastern Canada. Based on the Weitzman approach, the loss of the Sable Island horse population to the overall diversity in Canada is comparable or higher than any other horse breed. The Sable Island horse population has diverged enough from other breeds to deserve special attention by conservation interest groups.     

The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes

• 1 The New Zealand (NZ) sea lion Phocarctos hookeri is NZ's only endemic pinniped and is listed as ‘nationally critical’. The species breeds in the NZ sub‐Antarctic: 71% of the population at the Auckland Islands (2010 pup production: 1814 ± 39) and the remaining 29% on Campbell Island (726 pups in 2010).
• 2 Pup production at the Auckland Islands has declined by 40% since 1998 (1998: 3021 pups produced): only 1501 pups were born in 2009. This decline is directly linked to philopatric females not returning to breeding areas. While the Auckland Island population has declined, the Campbell Island population appears to be increasing slowly.
• 3 Potential reasons for the decline in the Auckland Island population, but not in the Campbell Island population, include non‐anthropogenic factors: (i) disease epizootics, (ii) predation, (iii) permanent dispersal or migration, (iv) environmental change; and anthropogenic impacts: (v) population ‘overshoot’, (vi) genetic effects, (vii) effects of contaminants, (viii) indirect effects of fisheries (i.e. resource competition) and (ix) direct effects of fisheries (i.e. by‐catch deaths). Of the nine potential reasons examined here, six can be discounted (ii–vii). Bacterial epizootics (i) occur in the NZ sea lion population, but their impact has predominantly increased pup mortality, which is unlikely to cause the severe decline observed, as pup mortality throughout the species is naturally high and variable.
• 4 The most plausible hypotheses, based on available evidence, are that the observed decline, in particular, the decreasing number of breeding females in the Auckland Island population, is caused by (viii) fisheries‐induced resource competition and (ix) fisheries‐related by‐catch. By‐catch is the main known anthropogenic cause of mortality in the species. Competition with fisheries resulting in resource competition, nutrient stress and decreased reproductive ability in NZ sea lions should be a priority area for future research.

     

Estimating Population Growth and Recruitment Rates Across the Range of American Common Eiders

Sound management of bird populations rests upon an adequate understanding of their population dynamics. Our study evaluated recruitment and population growth rates of 14 American common eider (Somateria mollissima dresseri) colonies from Labrador, Nova Scotia, Quebec, Canada, and Maine, USA, during various periods between 1970 and 2019. We used Pradel mark-recapture models to estimate colony-specific growth rates and the relative contributions of survival and recruitment on growth. We also validated this approach using annual nest counts (~8,000 pairs) conducted between 2003 and 2019 during down harvest operations in 3 colonies located in the Saint Lawrence estuary in Quebec. There was generally a good agreement between estimates derived using the 2 approaches. We considered that capture-recapture data were suitable to estimate population trends of common eiders in other colonies, especially for colonies where accurate nest monitoring is impaired by dense vegetation. The breeding abundance declined at major colonies in Maine and Nova Scotia and increased or was stable in Quebec and Labrador. Female survival contributed the most to population growth, but variation in recruitment among colonies was more important than variation in survival to explain population growth. Management measures should thus strive to maximize local recruitment in colonies with declining populations. The assumption that apparent survival probabilities were homogeneous throughout an individual capture history was violated at several colonies in Quebec and Labrador. Using recaptures and band recoveries, we showed that the lower apparent survival for newly marked individuals compared to females that had been recaptured at least once was caused by a difference in site fidelity rather than true survival. But <1% of recaptured females dispersed to another colony for breeding, indicating that the lower site fidelity could be related to heterogeneity in capture probability among individuals. © 2021 The Wildlife Society.     

The relative influence of age and weight on the reproductive behaviour of male grey seals Halichoerus grypus

The breeding behaviour of male grey seals Halichoerus grypus of known age and weight was studied on Sable Island, Nova Scotia. Branded males ranged in age from 8 to 16 years and although there was a positive relationship between age and weight, there was a large overlap between age classes. In general, there was an increase in length of tenure and rates of copulation with increasing male age but this was less marked among males between the ages of 13 and 16 years. Compared to older ones, males of 8 and 12 years were observed at more sites, travelled more extensively around the breeding colony, were transient more frequently and were unable to lie as close to females. There was no correlation between male body weight and either length of tenure or rates of copulation when males of age 8 (the smallest males) were excluded from the analysis. Most agonistic behaviour was made by larger, older males towards smaller, younger ones and appeared to be responsible for the short length of tenure and low reproductive rates of young bulls.     

The rate of fertilization in male mating tactics of the polygynous grey seal

Studies using molecular markers have shown that some grey seal males may be gaining success through exhibiting alternative mating tactics. We estimated the probability of fertilization success of grey seal males exhibiting the primary tactic of female defence and one alternative tactic of mating with departing females on Sable Island, Nova Scotia, Canada, during the breeding seasons of 1997-2002. Although the fertilization rate of the primary tactic (27-43%) was greater than that of the alternative tactic (10-12%), these low rates indicate the potential fitness value of alternative mating tactics in this size-dimorphic pinniped species.     

Foraging locations of female New Zealand sea lions (

Figure of Eight Island is located in the southern end of the Auckland Islands and hosts the smallest breeding colony of New Zealand (NZ) sea lions (Phocarctos hookeri). Between 1995/96 and 2005/06, pup production in this colony decreased by 57% (from 144 to 62 pups). In contrast, there was a 30% decrease in pup production in the largest colony in the north-east of the Auckland Islands over the same period. NZ sea lions in the Auckland Islands area are subject to by-catch deaths and resource competition from subantarctic trawl fisheries. The present study investigated where four lactating females from Figure of Eight Island foraged during the austral summer of 2007/08 and compared their foraging areas with female NZ sea lions from the northern Auckland Islands breeding locations (Enderby and Dundas islands) and with fisheries activities. Females foraged south of Adams Island (the southernmost Auckland Island), predominantly at the edge of the Auckland Islands shelf, but those from Figure of Eight Island made shorter foraging trips within more concentrated areas than females from Enderby or Dundas islands. The 59 female NZ sea lions satellite-tracked to date from Figure of Eight, Enderby and Dundas islands foraged over the entire area of the Auckland Islands shelf and many (including three of the four females from Figure of Eight Island) had extensive overlap with subantarctic trawl fisheries. Further research is needed to determine whether the foraging behaviour of females from Figure of Eight Island is linked to their greater decline in pup production.