Variation in the Secondary Sex-Ratio of the Grey Seal Halichoerus grypus (Fab.) during the Breeding Season

Nature ◽  
1961 ◽  
Vol 190 (4772) ◽  
pp. 281-281 ◽  
Author(s):  
J. C. COULSON ◽  
GRACE HICKLING
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Secondary Sex Ratio

Diving behaviour during the breeding season in the terrestrially breeding male grey seal: implications for alternative mating tactics

2003 ◽  
Vol 81 (6) ◽  
pp. 1025-1033 ◽  
Author(s):  
Damian C Lidgard ◽  
Daryl J Boness ◽  
W Don Bowen ◽  
Jim I McMillan
Keyword(s):  
Nova Scotia ◽  
Reproductive Success ◽  
Breeding Season ◽  
Foraging Behaviour ◽  
Diving Behaviour ◽  
Halichoerus Grypus ◽  
Phenotypic Traits ◽  
Alternative Mating Tactics ◽  
Grey Seal ◽  
Mating Tactics

We examined the diving behaviour of breeding male grey seals (Halichoerus grypus) at Sable Island, Nova Scotia, from 1997 to 2001. The proportion of time spent at sea varied between 0 and 78% (N = 30). Males engaged in deep (43.4 ± 3.3 m (mean ± SE), N = 27) diving, and these dives were clustered into bouts, which mostly occurred during long trips (62.2 ± 14.7 h). We suggest that males spent time foraging during deep dives. Shallow diving (5.9 ± 0.1 m, N = 27) accounted for 40.8% of dives, which were also clustered into bouts that mostly occurred during short trips (2.1 ± 0.37 h). We suggest that shallow diving comprised a suite of behaviours, but included little foraging behaviour. Phenotypic traits had little influence on diving behaviour. Further work is required to understand the extent to which foraging behaviour enhances reproductive success, and whether shallow diving is a component of the mating tactics of male grey seals at Sable Island.

Individually distinctive pup vocalizations fail to prevent allo-suckling in grey seals

1999 ◽  
Vol 77 (5) ◽  
pp. 716-723 ◽  
Author(s):  
Susanne McCulloch ◽  
Patrick P Pomeroy ◽  
Peter JB Slater
Keyword(s):  
Breeding Season ◽  
Individual Recognition ◽  
Mutual Recognition ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Playback Experiments ◽  
Auditory Cues ◽  
Distinctive Features ◽  
Vocal Recognition

In crowded aggregations that occur in breeding colonies, female pinnipeds commonly become separated from their pups and may use spatial, olfactory, or auditory cues to locate them. A system of mutual recognition based on vocalizations is known for otariids. Female phocids are known to use location and olfaction to help identify pups, but evidence for vocal recognition is weak. During the 1997 breeding season on the Isle of May, Scotland, vocalizations were recorded from grey seal, Halichoerus grypus, pups; playback experiments were carried out; and nursing of nonfilial pups was observed. Pup vocalizations were found to be both stereotyped and individually distinctive, features normally associated with a system of individual recognition. However, playback experiments revealed that mothers did not respond more to vocalizations of their own pups than to those of nonfilial pups. Furthermore, seventeen cases of allo-suckling were observed during 68 h of observation on the colony. High densities of animals and frequent separations present challenges to identification of pups by their mothers.

Utilizing next-generation sequencing to identify prey DNA in western North Atlantic grey seal Halichoerus grypus diet

2020 ◽  
Vol 655 ◽  
pp. 227-240
Author(s):  
KR Flanders ◽  
ZH Olson ◽  
KA Ono
Keyword(s):  
Next Generation Sequencing ◽  
Feeding Habits ◽  
Atlantic Menhaden ◽  
Halichoerus Grypus ◽  
Frequency Of Occurrence ◽  
Grey Seal ◽  
Next Generation ◽  
Significant Difference ◽  
Generation Sequencing ◽  
Seal Diet

Increasing grey seal Halichoerus grypus abundance in coastal New England is leading to social, political, economic, and ecological controversies. Central to these issues is the foraging ecology and diet composition of the seals. We studied grey seal feeding habits through next-generation sequencing of prey DNA using 16S amplicons from seal scat (n = 74) collected from a breeding colony on Monomoy Island in Massachusetts, USA, and report frequency of occurrence and relative read abundance. We also assigned seal sex to scat samples using a revised PCR assay. In contrast to current understanding of grey seal diet from hard parts and fatty acid analysis, we found no significant difference between male and female diet measured by alpha and beta diversity. Overall, we detected 24 prey groups, 18 of which resolved to species. Sand lance Ammodytes spp. were the most frequently consumed prey group, with a frequency of occurrence (FO) of 97.3%, consistent with previous studies, but Atlantic menhaden Brevoortia tyrannus, the second most frequently consumed species (FO = 60.8%), has not previously been documented in US grey seal diet. Our results suggest that a metabarcoding approach to seal food habits can yield important new ecological insights, but that traditional hard parts analysis does not underestimate consumption of Atlantic cod Gadus morhua (FO = 6.7%, Gadidae spp.) and salmon Salmo salar (FO = 0%), 2 particularly valuable species of concern.

scholarly journals Maternal exposure to airborne polychlorinated biphenyls (PCBs) and risk of adverse birth outcomes

2021 ◽  
Author(s):  
Ane Bungum Kofoed ◽  
Laura Deen ◽  
Karin Sørig Hougaard ◽  
Kajsa Ugelvig Petersen ◽  
Harald William Meyer ◽  
...  
Keyword(s):  
Birth Weight ◽  
Preterm Birth ◽  
Sex Ratio ◽  
Polychlorinated Biphenyls ◽  
Birth Outcomes ◽  
Gestational Age ◽  
Small For Gestational Age ◽  
Maternal Exposure ◽  
Adverse Birth Outcomes ◽  
Secondary Sex Ratio

AbstractHuman health effects of airborne lower-chlorinated polychlorinated biphenyls (LC-PCBs) are largely unexplored. Since PCBs may cross the placenta, maternal exposure could potentially have negative consequences for fetal development. We aimed to determine if exposure to airborne PCB during pregnancy was associated with adverse birth outcomes. In this cohort study, exposed women had lived in PCB contaminated apartments at least one year during the 3.6 years before conception or the entire first trimester of pregnancy. The women and their children were followed for birth outcomes in Danish health registers. Logistic regression was performed to estimate odds ratios (OR) for changes in secondary sex ratio, preterm birth, major congenital malformations, cryptorchidism, and being born small for gestational age. We performed linear regression to estimate difference in birth weight among children of exposed and unexposed mothers. All models were adjusted for maternal age, educational level, ethnicity, and calendar time. We identified 885 exposed pregnancies and 3327 unexposed pregnancies. Relative to unexposed women, exposed women had OR 0.97 (95% CI 0.82, 1.15) for secondary sex ratio, OR 1.13 (95% CI 0.76, 1.67) for preterm birth, OR 1.28 (95% CI 0.81, 2.01) for having a child with major malformations, OR 1.73 (95% CI 1.01, 2.95) for cryptorchidism and OR 1.23 (95% CI 0.88, 1.72) for giving birth to a child born small for gestational age. The difference in birth weight for children of exposed compared to unexposed women was − 32 g (95% CI—79, 14). We observed an increased risk of cryptorchidism among boys after maternal airborne LC-PCB exposure, but due to the proxy measure of exposure, inability to perform dose–response analyses, and the lack of comparable literature, larger cohort studies with direct measures of exposure are needed to investigate the safety of airborne LC-PCB exposure during pregnancy

Biology of the Feral Cat, Felis Catus (L.), On Macquarie Island.

1985 ◽  
Vol 12 (3) ◽  
pp. 425 ◽  
Author(s):  
NP Brothers ◽  
IJ Skira ◽  
GR Copson
Keyword(s):  
Sex Ratio ◽  
Breeding Season ◽  
Felis Catus ◽  
Feral Cat ◽  
Feral Cats ◽  
Macquarie Island ◽  
Pregnant Females

246 feral cats were shot on Macquarie Island, Australia, between Dec. 1976 and Feb. 1981. The sex ratio ( males : females ) was 1:0.8. The percentages of animals with tabby, orange and black coats were 74, 26 and 2 resp. [sic]. Of the 64 orange cats, 56 were males . The breeding season was Oct.-Mar., with a peak in Nov.-Dec. The number of embryos in the 14 pregnant females averaged 4.7 (range = 1-9). The size of the 23 litters that were observed averaged 3 (range = 1-8). Kitten survival to 6 months of age was estimated to be <43%.

Predation by Sharks on the Grey Seal (Halichoerus grypus) in Eastern Canada

1983 ◽  
Vol 40 (3) ◽  
pp. 267-271 ◽  
Author(s):  
Paul Brodie ◽  
Brian Beck
Keyword(s):  
Key Words ◽  
Population Size ◽  
Halichoerus Grypus ◽  
Longline Fishery ◽  
Grey Seal ◽  
Eastern Canada ◽  
The Past ◽  
Harbour Seals ◽  
Commercially Important ◽  
Important Fish

The increase in population size of the grey seal (Halichoerus grypus) off eastern Canada over the past 20 yr may be attributed to a decrease in shark stocks, their supposed predators. Reduction of the shark population is presumed to have resulted from a directed longline fishery and, of greater significance, from a change in the fishery for swordfish (Xiphias gladius) from selective harpooning to pelagic longlining, which has produced a large bycatch of sharks. The resulting enhanced survival of grey seals is reflected in greater infestation of commercially important fish species by the codworm (Phocanema decipiens).Key words: grey seals, harbour seals, sharks, swordfish, codworm, predation, fisheries

Does preconception stress alter the secondary sex ratio?

2011 ◽  
Vol 96 (3) ◽  
pp. S154
Author(s):  
R.J. Chason ◽  
R. Sundaram ◽  
G.M. Buck Louis ◽  
J.H. Segars ◽  
C. Pyper
Keyword(s):  
Sex Ratio ◽  
Secondary Sex Ratio
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