scholarly journals Effect of Food Availability on Arrival and Departure Decisions of Harlequin Ducks at Diurnal Feeding Grounds

The Condor ◽  
2001 ◽  
Vol 103 (4) ◽  
pp. 870-874 ◽  
Author(s):  
Michael S. Rodway ◽  
Fred Cooke
Keyword(s):  
Food Availability ◽  
Food Supplementation ◽  
Natural Food ◽  
Clupea Pallasi ◽  
Histrionicus Histrionicus ◽  
Before And After ◽  
Harlequin Ducks ◽  
Near Shore ◽  
Effect Of Food ◽  
Departure Decisions

Abstract We investigated three types of decisions made by Harlequin Ducks (Histrionicus histrionicus) in moving between nearshore feeding and offshore resting areas: when to move, whether to move synchronously, and whether to form dense flocks on the roosting grounds. We used the spawning of Pacific herring (Clupea pallasi) as a natural food-supplementation experiment. Birds arrived at nearshore feeding areas a few minutes later and departed almost an hour earlier relative to sunrise and sunset when spawn was available than before and after. Cloud cover and high winds resulted in earlier departures, especially during spawning. Arriving, departing, and offshore groups consisted most frequently of two ducks, and birds showed little tendency to synchronize movements or to form dense flocks when resting. Results indicate that Harlequin Ducks avoid crepuscular and nocturnal periods near shore when not constrained by food availability and the length of daylight in which to feed. Efecto de la Disponibilidad de Alimento en las Decisiones de Arribo y Partida de Histrionicus histrionicus en Áreas de Alimentación Diurna Resumen. Investigamos tres tipos de decisiones hechas por Histrionicus histrionicus (Pato Arlequín) al moverse entre áreas de alimentación cercanas a la costa y áreas de reposo mar adentro: cuándo moverse, si se mueven de modo sincrónico, y si forman bandadas densas en las áreas de reposo. Utilizamos el desove del arenque del Pacífico (Clupea pallasi) como un experimento de suplemento de alimento natural. En relación al amanecer y anochecer, las aves llegaron a las áreas de alimentación cercanas a la costa unos minutos después y se fueron casi una hora más temprano cuando los huevos de peces estuvieron disponibles que cuando no lo estuvieron, ya sea antes o después. Cobertura de nubes y fuertes vientos trajeron aparejadas partidas más tempranas, especialmente durante la etapa de desove. Los grupos que llegaban, partían y los que se encontraban mar adentro estuvieron en su mayoría conformados por dos patos, y las aves en general no tendieron a sincronizar sus movimientos o a formar grupos densos durante el reposo. Los resultados indican que H. histrionicus evita permanecer cerca de la costa durante períodos crepusculares y nocturnos cuando no se haya limitado por la disponibilidad de alimentos y por la cantidad de horas de luz para alimentarse.

Food shortage for breeding Black-billed Magpies (Pica pica): an experiment using supplemental food

1987 ◽  
Vol 65 (5) ◽  
pp. 1270-1274 ◽  
Author(s):  
Wesley M. Hochachka ◽  
David A. Boag
Keyword(s):  
Breeding Population ◽  
Egg Laying ◽  
Food Shortage ◽  
Laying Date ◽  
Food Supplementation ◽  
Natural Food ◽  
Supplemental Feeding ◽  
Pica Pica ◽  
Supplemental Food ◽  
Before And After

Supplemental food was provided to a breeding population of Black-billed Magpies (Pica pica), starting before and after eggs were laid, to determine if and when natural food was limited. The production of fledgling magpies was increased only when supplemental feeding was begun before laying. Laying date was also advanced when supplemental feeding began before laying, but clutch and egg size were not significantly changed. Because the two feeding treatments were conducted in different years, we cannot conclude whether natural food was limiting before or after egg laying. However, out data suggest that the former may have been the case. An improved design for food supplementation experiments, which can be used to determine the time of food shortage, is suggested.

Differential sex-related winter energetics in free-ranging snowshoe hares (Lepus americanus)

2016 ◽  
Vol 94 (2) ◽  
pp. 115-121 ◽  
Author(s):  
E. Ellsworth ◽  
M.R. Boudreau ◽  
K. Nagy ◽  
J.L. Rachlow ◽  
D.L. Murray
Keyword(s):  
Energy Expenditure ◽  
Food Availability ◽  
Lepus Americanus ◽  
Energetic Cost ◽  
Food Supplementation ◽  
Natural Food ◽  
Daily Energy Expenditure ◽  
Snowshoe Hares ◽  
Daily Energy ◽  
Free Ranging

Animals spend considerable time and energy acquiring food to meet their metabolic requirements, but if energetic or fitness costs are substantive, such as during winter, then some individuals may limit daily energy expenditure by reducing foraging duration. To date, the prevalence and magnitude of such compensatory foraging responses are poorly known. We examined energy balance compensation in free-ranging snowshoe hares (Lepus americanus Erxleben, 1777) via a food supplementation experiment to determine whether individuals reduced their daily energy expenditure (DEE) and activity periods in response to increased food availability. Overall, food supplementation had no effect on diel activity patterns, although males had higher DEE compared with females. During early and mid-winter, hares did not alter their activity periods in response to food supplementation, but during late winter, when natural food availability declined, food-supplemented females (but not males) were ∼11% less active compared with controls. Natural food likely was sufficient and could have been acquired at relatively low energetic cost, but because males likely have higher DEE due to mating behavior whereas females may limit their activity (and thus DEE) to reduce predation risk, we conclude that gender-specific life-history demands can over-ride predicted responses to supplemental food when baseline food abundance is adequate.

scholarly journals Vigilance Behavior in the Harlequin Duck (Histrionicus Histrionicus) During the Preincubation Period in Labrador: Are Males Vigilant for Self or Social Partner?

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 241-252
Author(s):  
Kelly A. Squires ◽  
Kathy Martin ◽  
R. Ian Goudie
Keyword(s):  
Social Partner ◽  
Sexually Dimorphic ◽  
Fertile Period ◽  
Female Partners ◽  
Histrionicus Histrionicus ◽  
Harlequin Ducks ◽  
Female Survival ◽  
Near Shore ◽  
Self Protection ◽  
Dimorphic Species

Abstract Males of several avian species are more vigilant than their female partners, particularly during the preincubation period. Male vigilance may function as a deterrent of extrapair copulation attempts (EPCs) or to ensure male survival, because males of sexually dimorphic species may be more conspicuous to predators than females. However, vigilant males may act as antipredator sentinels to enhance female survivorship, which may also allow females to feed and rest more efficiently, thereby enhancing their ability to form clutches. We attempted to distinguish between the “male benefits” and “female benefits” hypotheses by studying the behavior of unpaired males and paired Harlequin Ducks (Histrionicus histrionicus) during the preincubation period. Paired males were, on average, four times more vigilant than unpaired males and their mates, which suggests that elevated levels of vigilance by paired males does not function primarily for self-protection against predators. Males were not more vigilant during the female’s fertile period, contrary to the “paternity assurance” hypothesis. Male vigilance during feeding bouts was highest when pairs fed alone near shore—a condition in which feeding was likely more “risky.” Male vigilance was positively correlated with female feeding when females fed near shore, but not at other times. During resting bouts, males were vigilant 14 ± 0.01% of the time in all conditions. We suggest that male vigilance may be important to enhance female survival, especially when females feed under risky conditions. Comportement de Vigilance chez Histrionicus histrionicus durant la Période de Pré- incubation au Labrador: Les Mâles Sont-ils Vigilants pour Eux-mêmes ou pour leur Partenaire Social?

Food supplementation and abundance estimation in the white-footed mouse

2006 ◽  
Vol 84 (8) ◽  
pp. 1210-1215 ◽  
Author(s):  
Pei-Jen L. Shaner
Keyword(s):  
Population Dynamics ◽  
Food Availability ◽  
Robust Design ◽  
Meta Analysis ◽  
Design Model ◽  
Food Supplementation ◽  
Abundance Estimates ◽  
Abundance Indices ◽  
Consumer Population ◽  
White Footed Mouse

Food availability often drives consumer population dynamics. However, food availability may also influence capture probability, which if not accounted for may create bias in estimating consumer abundance and confound the effects of food availability on consumer population dynamics. This study compared two commonly used abundance indices (minimum number alive (MNA) and number of animals captured per night per grid) with an abundance estimator based on robust design model as applied to the white-footed mouse ( Peromyscus leucopus (Rafinesque, 1818)) in food supplementation experiments. MNA consistently generated abundance estimates similar to the robust design model, regardless of food supplementation. The number of animals captured per night per grid, however, consistently generated lower abundance estimates compared with MNA and the robust design model. Nevertheless, the correlations between abundance estimates from MNA, number of animals captured, and robust design model were not influenced by food supplementation. This study demonstrated that food supplementation is not likely to create bias among these different measures of abundance. Therefore, there is a great potential for conducting meta-analysis of food supplementation effect on consumer population dynamics (particularly in small mammals) across studies using different abundance indices and estimators.

Daily changes in food availability, but not long-term unpredictability, determine daily torpor-bout occurrences and frequency in stripe-faced dunnarts (Sminthopsis macroura)

2015 ◽  
Vol 63 (1) ◽  
pp. 12 ◽  
Author(s):  
Alexandra M. Leslie ◽  
Mathew Stewart ◽  
Elizabeth Price ◽  
Adam J. Munn
Keyword(s):  
Food Availability ◽  
Control Period ◽  
Daily Torpor ◽  
Torpor Bout ◽  
Effect Of Food ◽  
Rapid Adjustment ◽  
Sminthopsis Macroura ◽  
Ad Libitum ◽  
Ad Libitum Intake ◽  
Ad Libitum Feeding

Daily torpor, a short-term reduction in body temperature and metabolism, is an energy-saving strategy that has been interpreted as an adaptation to unpredictable resource availability. However, the effect of food-supply variability on torpor, separately from consistent food restriction, remains largely unexamined. In this study, we investigated the effect of unpredictable food availability on torpor in stripe-faced dunnarts (Sminthopsis macroura). After a control period of ad libitum feeding, dunnarts were offered 65% of their average daily ad libitum intake over 31 days, either as a constant restriction (i.e. as equal amount of food offered each day) or as an unpredictable schedule of feed offered, varied daily as 0%, 30%, 60%, 100% or 130% of ad libitum. Both feeding groups had increased torpor-bout occurrences (as a proportion of all dunnarts on a given day) and torpor-bout frequency (average number of bouts each day) when on a restricted diet compared with ad libitum feeding, but torpor frequency did not differ between the consistently restricted and unpredictably restricted groups. Most importantly, torpor occurrence and daily bout frequency by the unpredictably restricted group appeared to change in direct association with the amount of food offered on each day; torpor frequency was higher on days of low food availability. Our data do not support the interpretation that torpor is a response to unpredictable food availability per se, but rather that torpor allowed a rapid adjustment of energy expenditure to manage daily fluctuations in food availability.

Sign in / Sign up

Export Citation Format

Share Document