Diving behaviour of lactating harbour seals and their pups during maternal foraging trips

1999 ◽  
Vol 77 (6) ◽  
pp. 978-988 ◽  
Author(s):  
W D Bowen ◽  
D J Boness ◽  
S J Iverson
Keyword(s):  
Nova Scotia ◽  
Post Partum ◽  
Dive Duration ◽  
Phoca Vitulina ◽  
Diving Behaviour ◽  
Early Lactation ◽  
Adult Females ◽  
Harbour Seals ◽  
Lactating Females

Female harbour seals (Phoca vitulina) undertake foraging trips during mid to late lactation. We show that they are accompanied by their pup during many of these foraging trips. Time-depth recorder data were obtained from 20 lactating females and 14 of their pups in 1995 and 1996 at Sable Island, Nova Scotia. Overall, females spent 55.4 ± 4.68% (mean ± SE) of their time at sea compared with 39.8 ± 2.29% for pups. Like those of their mothers, pups' dives occurred in clusters or bouts: 71.4 ± 4.4 dives, 2.5 ± 0.15 h in duration. Bouts of diving by females and pups began 0-3 days post partum. Mean dive duration of pups increased from about 1 to 1.5 min over the course of lactation, but was still shorter than that of adult females (1.5-2.25 min). Both females and pups appeared to dive within their theoretical aerobic dive limits (TADL) of 8.9 and 2.6-3.1 min, respectively. Up to 3.6% of dives by some pups may have exceeded their TADL. Pups appeared to compensate for their lesser diving ability by making more and shorter dives per bout than females, particularly during early lactation.

Testing predictions of optimal diving theory using animal-borne video from harbour seals (Phoca vitulina concolor)

2014 ◽  
Vol 92 (4) ◽  
pp. 309-318 ◽  
Author(s):  
Susan G. Heaslip ◽  
W. Don Bowen ◽  
Sara J. Iverson
Keyword(s):  
Nova Scotia ◽  
Temporal Pattern ◽  
Dive Depth ◽  
Dive Duration ◽  
Phoca Vitulina ◽  
Encounter Rate ◽  
Harbour Seals ◽  
Wide Range ◽  
Oxygen Stores ◽  
Free Ranging

Optimal diving theory predicts that animals make decisions that maximize their foraging profitability subject to the constraint of oxygen stores. We examined the temporal pattern of prey encounters within a dive from concurrently collected dive data and animal-borne video from a free-ranging pinniped to test predictions of optimal diving theory. Crittercams were deployed on 32 adult male harbour seals (Phoca vitulina concolor De Kay, 1842) at Sable Island, Nova Scotia, Canada, for 3 days each. Deployments resulted in approximately 3 h of video per seal and a total of 2275 capture attempts for 1474 prey encounter events recorded. We found support for seven of the nine selected predictions of optimal diving theory. As predicted, prey encounters increased with bottom duration; dive duration increased with dive depth; and travel duration, bottom duration, and percent bottom duration decreased over a wide range of travel durations. Descent duration did increase with dive depth, and seals terminated dives earlier when no prey were encountered and when prey were encountered later in a dive. Contrary to prediction, bottom duration did not increase and then decrease for short travel durations and dives were not terminated earlier when travel durations were short and prey encounter rate was low.

Observations on a Colony of Whelping Harbour Seals, Phoca vitulina concolor, on Sable Island, Nova Scotia

1971 ◽  
Vol 28 (5) ◽  
pp. 755-759 ◽  
Author(s):  
Jean Boulva
Keyword(s):  
Nova Scotia ◽  
Phoca Vitulina ◽  
Harbour Seals ◽  
Seal Population ◽  
Males And Females

Three censuses indicated that approximately 1220 harbour seals were at Sable Island at the beginning of whelping in 1970. About 270 pups were born, representing 18% of the total seal population after whelping. Maximum whelping occurred during the last week of May. Males represented 52% of the 118 pups examined. At least 12% of the pups died in the 1st month of life. Pups born with lanugo represented 16% of all pups born. Males and females averaged 80 cm long and 11 kg in weight at birth; 3 weeks later, the males averaged 91 cm and 24 kg and the females 86 cm and 20 kg.

Thyroid hormone dynamics during the nursing period in harbour seals, Phoca vitulina

1998 ◽  
Vol 76 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Martin Haulena ◽  
David J Aubin ◽  
Padraig J Duignan
Keyword(s):  
Thyroid Hormones ◽  
Post Partum ◽  
Phoca Vitulina ◽  
Postnatal Period ◽  
Lactation Period ◽  
Harbour Seals ◽  
Total Thyroxine ◽  
Phocid Seals ◽  
Free Ranging ◽  
Circulating Levels

The postnatal period in phocid seals is metabolically demanding, requiring mobilization of maternal energy stores, which are then transferred via the milk for subsequent deposition in the pup. Thyroid hormones may be important modulators of these processes, and so we monitored circulating levels of free and total thyroxine (T4), triiodothyronine (T3), and reverse T3 (rT3) in 13 free-ranging female harbour seals (Phoca vitulina) and their pups for up to 25 days post partum. Early total and free T4 levels, percentage of free T4, total and free T3 levels, rT3 levels, and rT3:T3 ratios were significantly higher in pups than in mothers. Total and free T4 levels, percentage of free T4, free T3 and rT3, levels, and rT3:T3 ratios in pups decreased significantly over the lactation period, while maternal total and free T4 levels increased significantly. Our findings highlight the dynamic nature of thyroid hormones and their involvement in regulating metabolism throughout this important period. This is the first report examining free T3 and rT3 levels in phocid seals.

Maternal effects on offspring growth rate and weaning mass in harbour seals

2001 ◽  
Vol 79 (6) ◽  
pp. 1088-1101 ◽  
Author(s):  
W Don Bowen ◽  
Sara L Ellis ◽  
Sara J Iverson ◽  
Daryl J Boness
Keyword(s):  
Growth Rate ◽  
Nova Scotia ◽  
Path Analysis ◽  
Maternal Effects ◽  
Maternal Age ◽  
Mass Gain ◽  
Phoca Vitulina ◽  
Young Females ◽  
Harbour Seals ◽  
Offspring Growth

We studied maternal effects on offspring traits during lactation in harbour seals (Phoca vitulina) on Sable Island, Nova Scotia, from 1988 to 1996. Duration of lactation was correlated with rate of pup mass gain (r = %#150;0.34, n = 116) and weaning mass (r = 0.29, n = 154). Pups that grew faster had shorter nursing periods, whereas those that attained higher weaning masses nursed for a greater number of days. Pup sex did not affect patterns of maternal effects. The pups of young females (4%#150;6 years old) gained mass at a constant but lower rate (0.56 kg/d) than the pups of older females through midlactation (0.74%#150;0.78 kg/d; n = 75). In older females, rates of pup mass gain decelerated between mid and late lactation. Although maternal age did not directly affect weaning mass of pups, path analysis showed that maternal age acted on weaning mass through intermediary traits. Lighter females gave birth to smaller and slower growing pups, but invested relatively more than heavier females (n = 153). Effects of maternal postpartum mass on weaning mass (n = 100) were weaker in harbour seals than in phocids that fast during lactation, but apparently stronger than in otariids that forage during lactation, suggesting that the strength of maternal effects is influenced by lactation strategy.

Description of the Pregnancies, Labours, and Pre- and Post-Partum Events of Two Harbour Seals (Phoca vitulina) in a Zoological Environment

2006 ◽  
Vol 32 (2) ◽  
pp. 145-151 ◽  
Author(s):  
Marie-Anne Blanchet ◽  
Genevieve Desportes ◽  
Tiffany Nance ◽  
Cecilia Vanman
Keyword(s):  
Post Partum ◽  
Phoca Vitulina ◽  
Harbour Seals

The effect of maternal age and other factors on birth mass in the harbour seal

1994 ◽  
Vol 72 (1) ◽  
pp. 8-14 ◽  
Author(s):  
W. D. Bowen ◽  
O. T. Oftedal ◽  
D. J. Boness ◽  
S. J. Iverson
Keyword(s):  
Nova Scotia ◽  
Developmental Stage ◽  
Body Mass ◽  
Maternal Age ◽  
Phoca Vitulina ◽  
Harbour Seal ◽  
Birth Date ◽  
Young Mothers ◽  
Maternal Body ◽  
Harbour Seals

We studied the effects of maternal age, maternal body mass at parturition, year of birth, birth date, pup sex, and developmental stage (as indicated by the presence of a foetal pelage called lanugo) on the birth mass of harbour seals (Phoca vitulina) on Sable Island, Nova Scotia, Canada. Between 1987 and 1992, mass was obtained on 330 newborns and 259 of their mothers. Birth mass was significantly correlated with maternal mass (r = 0.42 for male pups; r = 0.32 for female pups). Among pups that had shed their lanugo, males were significantly heavier at birth (11.4 ± 0.09 kg, n = 107) than females (10.9 ± 0.09, n = 99). Birth mass increased significantly with maternal age (n = 71, range 4–12 years) even after the effects of maternal mass and pup sex were statistically removed. Mean birth mass varied significantly among years, from 10.5 to 11.5 kg. Newborns averaged 12.8% of maternal mass at parturition (84.8 ± 0.49 kg). Most (84%) pups had shed their lanugo before birth. Pups born with extensive lanugo were born earlier in the season and weighed about 20% less than pups born without lanugo. These data suggest that pups born with lanugo may be less developed than pups that had shed their foetal coat. Young mothers (4 and 5 years old) produced most of the underweight, lanugo-covered pups.

Pharmacological blockade of the dive response: effects on heart rate and diving behaviour in the harbour seal (Phoca vitulina)

2002 ◽  
Vol 205 (23) ◽  
pp. 3757-3765 ◽  
Author(s):  
Nicole M. Elliott ◽  
Russel D. Andrews ◽  
David R. Jones
Keyword(s):  
Heart Rate ◽  
Cardiovascular Responses ◽  
Video Camera ◽  
Phoca Vitulina ◽  
Diving Behaviour ◽  
Harbour Seals ◽  
Oxygen Stores ◽  
Adrenergic Blocker ◽  
Pharmacological Blockade ◽  
Dive Response

SUMMARYWhile diving, harbour seals (Phoca vitulina) manage their oxygen stores through cardiovascular adjustments, including bradycardia, a concurrent reduction in cardiac output, and peripheral vasoconstriction. At the surface,post-dive tachycardia facilitates rapid reloading of oxygen stores. Although harbour seals can tolerate >20 min of submergence, the majority of their natural dives are only 2-6 min and are usually followed by surface intervals that are <1 min, so they spend approximately 80% of their time submerged. Given that harbour seals meet their ecological needs through repetitive short aerobic dives, we were interested in the functional role, if any, of the dive response during these short dives. During voluntary diving in an 11 m deep tank, the cardiovascular responses to submergence of five harbour seals were manipulated using specific pharmacological antagonists, and the effects on diving behaviour were observed. Effects of pharmacological blockade on heart rate were also examined to assess the autonomic control of heart rate during voluntary diving. Heart rate was recorded using subcutaneous electrodes and data loggers, while diving behaviour was monitored using a video camera. The muscarinic blocker methoctramine blocked diving bradycardia, theα-adrenergic blocker prazosin blocked diving vasoconstriction, and theβ-adrenergic blocker metoprolol blocked post-dive tachycardia. Heart-rate analysis indicated that diving bradycardia is primarily modulated by the vagus, while post-dive tachycardia results from parasympathetic withdrawal as well as increased sympathetic stimulation of the heart. None of the pharmacological blockers had any effect on average dive or surface interval duration. Seals maintained a high percentage of time spent diving in all treatments. Thus, harbour seals do not appear to need the dive response during short dives in order to maintain an efficient dive strategy.

Diving behaviour of sub-adult harbour seals (Phoca vitulina) at Prins Karls Forland, Svalbard

Polar Biology ◽  
2002 ◽  
Vol 25 (3) ◽  
pp. 230-234 ◽  
Author(s):  
Bjørn A. Krafft ◽  
Christian Lydersen ◽  
Ian Gjertz ◽  
Kit M. Kovacs
Keyword(s):  
Phoca Vitulina ◽  
Diving Behaviour ◽  
Harbour Seals
Sign in / Sign up

Export Citation Format

Share Document