Time budget and diving behaviour of chick-rearing Crozet shags

2005 ◽  
Vol 83 (7) ◽  
pp. 971-982 ◽  
Author(s):  
Y Tremblay ◽  
T R Cook ◽  
Y Cherel

Blue-eyed shags are known to be capable of the deepest dives in the cormorant family. Yet, the way these birds balance their energy and time budgets remains enigmatic. Using ventrally attached time–depth recorders on chick-rearing Crozet shags (Phalacrocorax melanogenis Blyth, 1860), we simultaneously described their time budget and diving behaviour. Crozet shags are diurnal, benthic foragers (mean foraging range 1.7 km) that spend 37% of the daytime at sea. While at sea, they spend 49% of their time on the water, 44% diving, and 7% flying, and consume mainly benthic nototheniid fish. Larger fish (>20 g) were caught at shallower depths during shorter trips. They made, on average, 4.4 trips/day, each including 2.5 diving periods of 14 dives. On average, Crozet shags dove to 28 m (max. 145 m) for 2 min 2 s (max. 6 min 11 s). Descent and ascent rates became less variable at a depth of 40 m, possibly owing to a change in bird relative buoyancy at that depth. Ten percent of dives exceeded the estimated behavioural aerobic dive limit (4 min) and diving depths showed a bimodal distribution at <5 and ~18 m for dives lasting ~1 min. This dive duration corresponded to dives with higher dive duration/postdive interval ratios. The Crozet shags managed their dive cycle to fully exploit their breathing capacities, thus optimizing foraging performance.

1995 ◽  
Vol 73 (11) ◽  
pp. 1975-1982 ◽  
Author(s):  
Rodolfo Werner ◽  
Claudio Campagna

The diving behaviour of six lactating female southern sea lions (Otaria flavescens) was recorded during 52.4 animal-days at sea. Information was obtained from 18 057 dives. Females spent 52.7 ± 6.2% of the time at sea diving. Median and maximum dive depths ranged from 19 to 62 and from 97 to 175 m, respectively. Dives were short, with median and maximum durations ranging from 2.1 to 3.2 and from 4.4 to 7.7 min, respectively. Dives deeper than 10 m represented 56 – 89% of total dives and involved 93 – 97% of total diving time. Mean dive depth and duration of dives greater than 10 m were 61 m and 3 min, respectively. Most of these dives (69%) had a flat-bottomed U-shaped profile, bottom time constituting about half of the dive duration. Shallow dives, with a modal depth of 2 m, were short (median duration 0.1 –0.8 min), with virtually no time spent at the bottom of the dive. During trips to sea, which ranged from less than 1 day to more than 4 days, females dove continuously. Mean dive frequency was between 11 and 19 per hour. Surface intervals were short (median 0.9–1.2 min) and there was no apparent diel variation in dive depth or frequency. The estimated aerobic dive limit of the females was exceeded on only a few dives (0.7 – 6.2%). Transit to potential foraging areas took 0.2–8.3 h.


2011 ◽  
Vol 57 (3) ◽  
pp. 223-246 ◽  
Author(s):  
Solomon A. Tadesse ◽  
Burt P. Kotler

Nubian ibex (Capra nubiana) prefer steep terrain in their landscape to reduce risks of predation and human nuisance disturbances. They also use vigilance and time allocation to manage risk of predation. We studied time budgets and habitat selection of Nubian ibex to: (1) identify the habitat variables to which Nubian ibex were behaviorally responsive; (2) investigate how time budget responses of Nubian ibex were related to season, slope condition, group size, and sex-age structure; and (3) develop behavioral-based models that account for the variations in the behaviors of Nubian ibex across the landscape and seasons.To quantify time budgets, we took regular field observations on focal individuals of Nubian ibex classified according to their habitat, group size, sex, and age. For each focal observation, we quantified environmental variables that were thought to influence the behavioral responses of ibex. Then, we developed behavioral models by correlating the proportion of behaviors measured in focal animal observations to the influential environmental variables. The behaviors of Nubian ibex significantly varied with sex and age structure, season, habitat type, and slope conditions. Adult females are more vigilant than adult male ibex, especially in the spring. This correlates with breeding and nursing activities. Based on the characteristics of the habitat, ibex behave to minimize risks of predation and human nuisance disturbances while maximizing their food intake.


1992 ◽  
Vol 165 (1) ◽  
pp. 181-194 ◽  
Author(s):  
M. A. Castellini ◽  
G. L. Kooyman ◽  
P. J. Ponganis

The metabolic rates of freely diving Weddell seals were measured using modern methods of on-line computer analysis coupled to oxygen consumption instrumentation. Oxygen consumption values were collected during sleep, resting periods while awake and during diving periods with the seals breathing at the surface of the water in an experimental sea-ice hole in Antarctica. Oxygen consumption during diving was not elevated over resting values but was statistically about 1.5 times greater than sleeping values. The metabolic rate of diving declined with increasing dive duration, but there was no significant difference between resting rates and rates in dives lasting up to 82 min. Swimming speed, measured with a microprocessor velocity recorder, was constant in each animal. Calculations of the aerobic dive limit of these seals were made from the oxygen consumption values and demonstrated that most dives were within this theoretical limit. The results indicate that the cost of diving is remarkably low in Weddell seals relative to other diving mammals and birds.


2018 ◽  
Vol 11 (2) ◽  
pp. 67-73
Author(s):  
Brad T. McLeod ◽  
Gary Ritchison

Breeding is energetically costly and, if energy-limited, birds may alter their time budgets, spending less time engaged in some activities and more time in others. Investigators who have provided breeding birds with supplemental food have noted changes in time budgets, but the extent and types of changes have been found to vary among species. Our objective was to determine how food supplementation might influence the time budgets and paternity status of male Indigo Buntings (Passerina cyanea). We studied Indigo Buntings from 8 May to 15 August 2009 in Madison County, Kentucky. Territories of male Indigo Buntings (n=30) were randomly assigned as either food supplemented (n=8) or controls (n=22). During time-budget observations, all behaviours were noted. To determine paternity status, blood samples were collected from adults and nestlings at 16 nests. Males with feeders in their territories spent significantly less time foraging and more time vocalising (chip notes) than males without feeders. Time spent singing and mate guarding by treatment and control males did not differ. Differences in the proportion of extra-pair young did not differ between nests in territories with and without supplemental food. Our results suggest that, when provided with supplemental food, male Indigo Buntings spend less time foraging and more time engaged in other activities. However, neither the presence of supplemental food nor differences in the behaviour of males in food-supplemented versus non-supplemented territories affected rates of extra-pair paternity.


2002 ◽  
Vol 80 (9) ◽  
pp. 1643-1648 ◽  
Author(s):  
Joseph J Nocera ◽  
Neil M Burgess

Many species of diving birds adjust their foraging behaviour in response to variation in their environment. The Common Loon (Gavia immer) is a visually oriented predator sensitive to environmental variation, yet little is known about the flexibility of its diving behaviour. We tested the hypothesis that loons adjust their diving schedules by increasing or decreasing the dive duration during foraging bouts to accommodate environmental variation during the breeding season. The dive duration and dive-pause components of the loon dive cycle did not vary among lakes with different lake chemistry, lake morphometry, mercury levels in their blood, or fish abundance. We observed some variation among loons in different stages of breeding in mean dive-pause intervals. The dive-pause component of the diving cycle of Common Loons does not seem to be related to the amount of time spent underwater. To our knowledge, this is the first report of such a nonlinear relationship in diving birds. We propose that loons vary the components of their diving behaviour independently and seem to alter their diving time budgets regardless of the external stimuli we addressed. This unresponsive diving schedule may make loons susceptible to catastrophic changes in prey densities within their foraging areas, as they are obliged to forage on one, or very few, lakes. Conversely, loons may only forage in lakes with fish abundance above a certain minimum threshold and preferentially avoid lakes with reduced prey abundance.


1997 ◽  
Vol 75 (10) ◽  
pp. 1628-1635 ◽  
Author(s):  
Steeve D. Côté ◽  
James A. Schaefer ◽  
François Messier

Synchrony of activities and time budgets of age–sex classes of muskoxen (Ovibos moschatus) was studied on Victoria Island in the Canadian High Arctic during late winter (April – late May), spring (late May – early June) and summer (mid-June – July). As revealed by the kappa (κ) coefficient of agreement, herd members exhibited significant synchrony in 79 of 82 groups. The degree of synchrony was not related to group size in mixed herds but decreased with group size in bachelor herds. Diversity in age–sex classes, group type (mixed versus bachelor), and season did not affect synchrony. However, synchrony was less among adult males than among other age–sex classes. Muskoxen were more synchronised at the start of activity bouts than at the end. As revealed by principal components analysis, calves tended to spend more time lying and standing and less time feeding than other age–sex classes. In addition, males in bachelor groups tended to feed more and rest less than males in mixed herds. Duration of active and lying bouts was not affected by age–sex class. Length of active bouts did not change with season, but lying bouts decreased in length significantly from late winter to spring and from spring to summer. We suggest that synchrony of activities maintains group cohesion but constrains the time budget of some group members, especially adult males.


1997 ◽  
Vol 200 (4) ◽  
pp. 661-675 ◽  
Author(s):  
R M Bevan ◽  
I L Boyd ◽  
P J Butler ◽  
K Reid ◽  
A J Woakes ◽  
...  

The South Georgian shag (Phalacrocorax georgianus) shows a remarkable diving ability comparable to that of penguins, yet nothing is known of the physiology of these birds. In this study, heart rates and abdominal temperatures were recorded continuously in four free-ranging South Georgian shags using an implanted data-logger. A time&shy;depth recorder was also attached to the back of the implanted birds to record their diving behaviour. The diving behaviour of the birds was essentially similar to that reported in other studies, with maximum dive durations for individual birds ranging between 140 and 287 s, and maximum depths between 35 and 101 m. The birds, while at the nest, had a heart rate of 104.0&plusmn;13.1 beats min-1 (mean &plusmn; s.e.m.) and an abdominal temperature of 39.1&plusmn;0.2 &deg;C. During flights of 221&plusmn;29 s, heart rate and abdominal temperature rose to 309.5&plusmn;18.0 beats min-1 and 40.1&plusmn;0.3 &deg;C, respectively. The mean heart rate during diving, at 103.7&plusmn;13.7 beats min-1, was not significantly different from the resting values, but the minimum heart rate during a dive was significantly lower at 64.8&plusmn;5.8 beats min-1. The minimum heart rate during a dive was negatively correlated with both dive duration and dive depth. Abdominal temperature fell progressively during a diving bout, with a mean temperature at the end of a bout of 35.1&plusmn;1.7 &deg;C. The minimum heart rate during diving is at a sub-resting level, which suggests that the South Georgian shag responds to submersion with the 'classic' dive response of bradycardia and the associated peripheral vasoconstriction and utilisation of anaerobic metabolism. However, the reduction in abdominal temperature may reflect a reduction in the overall metabolic rate of the animal such that the bird can remain aerobic while submerged.


1986 ◽  
Vol 126 (1) ◽  
pp. 341-359 ◽  
Author(s):  
R. Stephenson ◽  
P. J. Butler ◽  
A. J. Woakes

Diving behaviour and heart rate were monitored in tufted ducks diving under circumstances which simulated various environmental conditions such as feeding under ice in winter. When distance to food was increased on a covered outdoor pond, dive duration increased proportionately, but it was calculated that time available for feeding was reduced during the longer-distance ‘extended’ dives. There was a gradual reduction in heart rate to 77.3 +/− 13.8 beats min-1, which is significantly lower than the resting value of 121.1 +/− 14.1 beats min-1, during the course of extended dives, suggesting that the ducks could gradually switch over to a ‘classical’ oxygen-conserving response during these prolonged voluntary dives. The duration of the pre-dive preparatory period was positively correlated with dive distance. When the ducks were briefly unable to resurface during an otherwise normal feeding dive in an indoor tank, a situation which may occur if they become disoriented under ice, there was an immediate switch to a full bradycardia. Reduction in heart rate during these ‘enclosed’ dives occurred only when the ducks were apparently aware of the situation and the rate of onset of bradycardia was very similar to that previously observed during involuntary submersion of tufted ducks. Minimum heart rate was the same at 46 beats min-1 after 15 s of enclosed dives and after 30 s of involuntary submersions, despite the differences in levels of activity in the two situations.


2002 ◽  
Vol 205 (24) ◽  
pp. 3769-3774 ◽  
Author(s):  
R. P. van Dam ◽  
P. J. Ponganis ◽  
K. V. Ponganis ◽  
D. H. Levenson ◽  
G. Marshall

SUMMARYDuring diving, intermittent swim stroke patterns, ranging from burst/coast locomotion to prolonged gliding, represent potential energy conservation mechanisms that could extend the duration of aerobic metabolism and, hence,increase the aerobic dive limit (ADL, dive duration associated with onset of lactate accumulation). A 5.6 min ADL for emperor penguins had been previously determined with lactate measurements after dives of &lt;50 m depth. In order to assess locomotory patterns during such dives, longitudinal acceleration was measured with an attached accelerometer in 44 dives of seven adult birds diving from an isolated dive hole in the sea ice of McMurdo Sound, Antarctica. Detection of wing strokes in processed accelerometer data was verified in selected birds with analysis of simultaneous Crittercam underwater video footage. Mean dive duration of birds equipped with the accelerometer and a time-depth recorder (TDR) was 5.7±2.2 min; 48% of these dives were greater than the measured 5.6 min ADL (ADLM). Highest stroke frequencies (0.92±0.31 Hz, N=981) occurred during the initial descent to 12 m depth. Swimming effort was reduced to a mean stroke frequency&lt;0.70 Hz during other phases of the dive (while traveling below 12 m depth,during foraging ascents/descents to and from the sub-ice surface, and during final ascents to exit). The longest stroke interval (8.6 s) occurred during a feeding excursion to the undersurface of the ice. In dives&gt;ADLM, mean stroke frequency during travel segments was significantly less than that in dives &lt;ADLM(P&lt;0.05). Mean stroke frequency of the entire dive correlated inversely (P&lt;0.05) with diving duration (r=-0.67) and with mean dive depth (r=-0.43). Emperor penguins did not exhibit any significant (&gt;10 s) periods of prolonged gliding during these shallow(&lt;60 m) foraging dives. However, a stroke/glide pattern was evident with more than 50% of strokes associated with a stroke interval &gt;1.6 s, and with lower stroke frequency associated with increased dive duration.


2016 ◽  
Vol 86 (1) ◽  
pp. 55 ◽  
Author(s):  
Elafri Ali ◽  
Halassi Ismahan ◽  
Houhamdi Moussa

We carried out a quantitative description of the use of a Mediterranean wetland (Tonga, North-east Algeria) by 22 waterbirds species (11 residents and 11 Palaearctic migrants) during late summer-wintering period, also analyzing their species-specific diurnal time budgets and the main related features of the landscape. The analyses of similarity in time budgets across birds (Hierarchal Cluster Analysis) showed four clusters of species associated with four major activities: day time mostly feeding (11 species), sleeping (6), swimming (3) and resting (2). Residents (Herons and Rails) showed a higher feeding time when compared to migrants (diving ducks, Gulls and Cormorants). From late summer to winter the time budget activity change in migrants; in contrast residents behave uniformly among daytime and at the course of the season. The use of this natural wetland in a complementary way by a high number of waterbirds (residents and migrants), is principally promoted by the existing of numerous habitat types. We found that 3 main ecological units, open water body, mudflats, and flooded meadows were the most utilized as foraging habitats among grebes, rails, ducks, gulls, and herons. In contrast, floating-leafed vegetation, and tall emergent vegetation were the commonest habitat categories used in resting activities especially by cormorants and herons. Data on behaviour requirements of these waterbirds can be used for conservation and correct management of this and other Mediterranean coastal wetlands.


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