Optimal annual routines: behaviour in the context of physiology and ecology

McNamara, John M.; Houston, Alasdair I.

doi:10.1098/rstb.2007.2141

Cited by 174 publications

(152 citation statements)

References 129 publications

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“…The baseline case of this version (table 1) is identical to the baseline energy-constraint case except that (i) background mortality is reduced, (ii) foraging incurs a predation risk, and (iii) foraging is more stochastic ( ). We introduce more stochasticity because, in K p 40 contrast to the energy-constraint case, we want the birds to be able to control their probability of starvation (see McNamara and Houston 1987;Houston and McNamara 1993). By comparing predictions of the two versions, we are able to understand what effects are primarily a consequence of energy constraints and what additional effects are the result of a trade-off between mortality (starvation and predation) and reproduction.…”

Section: Results From the Predation-risk Versionmentioning

confidence: 99%

“…The evolution of metabolic rate will depend on the negative effects of energy expenditure. As McNamara and Houston (2008) point out, hard work (i.e., a high rate of energy expenditure) has a variety of negative effects that act on different timescales. In this article, we have included a state variable that represents relatively short-term effects.…”

Section: Discussionmentioning

confidence: 99%

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A Theoretical Investigation of the Effect of Latitude on Avian Life Histories

McNamara¹,

Barta²,

Wikelski³

et al. 2008

The American Naturalist

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Online enhancements: appendixes.abstract: Tropical birds lay smaller clutches than birds breeding in temperate regions and care for their young for longer. We develop a model in which birds choose when and how often to breed and their clutch size, depending on their foraging ability and the food availability. The food supply is density dependent. Seasonal environments necessarily have a high food peak in summer; in winter, food levels drop below those characteristic of constant environments. A bird that cannot balance its energy needs during a week dies of starvation. If adult predation is negligible, birds in low seasonal environments are constrained by low food during breeding seasons, whereas birds in high seasonal environments die during the winter. Low food seasonality selects for small clutch sizes, long parental care times, greater age at first breeding, and high juvenile survival. The inclusion of adult predation has no major effect on any life-history variables. However, increased nest predation reduces clutch size. The same trends with seasonality are also found in a version of the model that includes a condition variable. Our results show that seasonal changes in food supply are sufficient to explain the observed trends in clutch size, care times, and age at first breeding.

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Section: Results From the Predation-risk Versionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A Theoretical Investigation of the Effect of Latitude on Avian Life Histories

McNamara¹,

Barta²,

Wikelski³

et al. 2008

The American Naturalist

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“…Similarly, Heath et al (2007) demonstrated that diving models based on rate maximization (Kramer 1988;Houston & Carbone 1992) were inadequate to explain diving patterns of foraging eider ducks, probably owing to longer term processes such as digestion. Behavioural routines can be influenced by a variety of physiological and ecological processes with different timescales, resulting in dynamics that may not be easily explained without formal analysis and precluding their study in isolation (McNamara et al 1987;McNamara & Houston 2008).…”

Section: Introductionmentioning

confidence: 99%

Interactions between rate processes with different timescales explain counterintuitive foraging patterns of arctic wintering eiders

2010

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To maximize fitness, animals must respond to a variety of processes that operate at different rates or timescales. Appropriate decisions could therefore involve complex interactions among these processes. For example, eiders wintering in the arctic sea ice must consider locomotion and physiology of diving for benthic invertebrates, digestive processing rate and a nonlinear decrease in profitability of diving as currents increase over the tidal cycle. Using a multi-scale dynamic modelling approach and continuous field observations of individuals, we demonstrate that the strategy that maximizes long-term energy gain involves resting during the most profitable foraging period (slack currents). These counterintuitive foraging patterns are an adaptive trade-off between multiple overlapping rate processes and cannot be explained by classical rate-maximizing optimization theory, which only considers a single timescale and predicts a constant rate of foraging. By reducing foraging and instead digesting during slack currents, eiders structure their activity in order to maximize long-term energetic gain over an entire tide cycle. This study reveals how counterintuitive patterns and a complex functional response can result from a simple trade-off among several overlapping rate processes, emphasizing the necessity of a multi-scale approach for understanding adaptive routines in the wild and evaluating mechanisms in ecological time series.

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“…They are also influenced by environment, which usually varies on multiple time scales, including daily, sea-sonally, annually, inter-annually and across decades. Where seasonal variation in food resources is high and predictable, animals should change their foraging strategies over the course of the year, and seasonal foraging strategies should be nested in a larger overarching annual strategy or routine (McNamara & Houston 2008).…”

Section: Introductionmentioning

confidence: 99%

Development of foraging strategies with age in a long-lived marine predator

Breed¹,

Bowen²,

Leonard³

2011

Mar. Ecol. Prog. Ser.

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The development of foraging strategies as animals mature depends upon experience, stage-specific physiology, the onset of reproductive maturity and the reproductive costs incurred by each sex. To understand the ontogeny of foraging behaviour, we compared movement behaviour of 24 young-of-year (YOY) juveniles (12 male, 12 female) with 6 subadult (4 male, 2 female) and 81 adult (43 male, 38 female) grey seals Halichoerus grypus. We used a behaviour discriminating state-space model followed by a series of mixed-effects models to examine trip structure and habitat use in these age classes. In foraging trips, tortuosity and speed of outbound travel were not different in YOY, subadults and adults, suggesting that YOY navigate as well as older animals. On average, however, YOY trips lasted 1.2 to 3.5 d longer and required up to twice as much transit time to reach foraging areas that were 1.5 to 3 times farther from haul-out sites than those of subadults and adults. This suggests an overall apparent higher foraging effort for YOY. Differences, however, were highly seasonally dependent. In all groups, apparent foraging effort decreased in the summer and increased in the winter, which is consistent with seasonal changes in prey distribution and energy content. Adult foraging patterns showed complex seasonal patterns influenced by both reproductive cycles and seasonal environmental variation, whereas annual foraging patterns of YOY and subadults, neither of which invest in reproduction, were simpler and appeared more closely tied to seasonal changes in prey availability and condition. Although foraging in the same habitats, male and female YOY showed small but significant differences in movement behaviour and trip structure. These differences are unlikely to be due to size difference, which is minimal at this age, and suggest that sex-related differences in foraging develop early before sexual size dimorphism is significantly expressed.

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Optimal annual routines: behaviour in the context of physiology and ecology

Cited by 174 publications

References 129 publications

A Theoretical Investigation of the Effect of Latitude on Avian Life Histories

A Theoretical Investigation of the Effect of Latitude on Avian Life Histories

Interactions between rate processes with different timescales explain counterintuitive foraging patterns of arctic wintering eiders

Development of foraging strategies with age in a long-lived marine predator

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