The effect of predator presence on body mass in captive greenfinches

Lilliendahl, Kristján

doi:10.1006/anbe.1996.0279

Cited by 91 publications

(78 citation statements)

References 23 publications

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“…Fransson & Weber 1997) and others during their wintering period (e.g. Lilliendahl 1997): this may have great e¡ects on their priorities in the allocation of their time and resources. This experiment suggested that di¡erences can exist within a species at di¡ering times of year.…”

Section: Discussionmentioning

confidence: 99%

Separating the effects of predation risk and interrupted foraging upon mass changes in the blue titParus caeruleus

Rands

Cuthill

2001

Proc. R. Soc. Lond. B

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The optimal amount of reserves that a small bird should carry depends upon a number of factors, including the availability of food and environmental predation risk levels. Theory predicts that, if predation risk increases, then a bird should maintain a lower level of reserves. Previous experiments have given mixed results: some have shown reduced reserves and some, increased reserves. However, the birds in these studies may have been interpreting a staged predation event as a period when they were unable to feed rather than a change in predation risk: theory predicts that, if the food supply within the environment is variable, then reserves should be increased. In the present study, we presented blue tits (Parus caeruleus) with a potential predator and compared this response (which could have been potentially confounded by perceived interruption e¡ects) with a response to an actual interruption in the environment during both long and short daytime lengths. During long (but not short) days, the birds responded in line with theoretical predictions by increasing their reserves in response to interruption and reducing them in response to predation. These results are examined in the light of other experimental manipulations and we discuss how well experimental tests have tested the predictions made by theoretical models.

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Section: Discussionmentioning

confidence: 99%

Separating the effects of predation risk and interrupted foraging upon mass changes in the blue titParus caeruleus

Rands

Cuthill

2001

Proc. R. Soc. Lond. B

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“…Empirical data on escape and flight behaviour has often supported these assumptions (Metcalfe and Ure, 1995;Kullberg et al, 1996;Lees et al, 2014;Van Den Hout et al, 2010;Nudds and Bryant, 2002;Lind et al, 1999); however, results that contradict these assumptions have also been reported (Kullberg, 1998;van der Veen and Lindström, 2000;Jones et al, 2009;Macleod, 2006;Dierschke, 2003). Empirical studies of changes in fat storage under changes in predation pressure largely support the idea that fat storage is reduced when predation pressure (or perceived predation pressure) increases (Gosler et al, 1995;Cresswell, 1998;Rogers, 2015;Pascual and Carlos Senar, 2015;Zimmer et al, 2011;MacLeod et al, 2007;Cimprich and Moore, 2006;Macleod et al, 2005a,b;Ydenberg et al, 2004;Pérez-Tris et al, 2004;Piersma et al, 2003;Gentle and Gosler, 2001;van der Veen, 1999;Carrascal and Polo, 1999;Fransson and Weber, 1997;Pravosudov and Grubb, 1998;Rogers, 1987;Witter et al, 1994; but see Lilliendahl 1997Lilliendahl , 1998. However, studies of birds killed by predators do not indicate that fatter birds are killed more frequently (Sullivan, 1989;Whitfield et al, 1999;Møller and Erritzøe, 2000;Genovart et al, 2010); indeed, some studies suggest that leaner birds are more prone to predation risk (Dierschke, 2003...…”

Section: Set-point Theorymentioning

confidence: 95%

The evolution of body fatness: trading off disease and predation risk

Speakman

2018

Journal of Experimental Biology

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Human obesity has a large genetic component, yet has many serious negative consequences. How this state of affairs has evolved has generated wide debate. The thrifty gene hypothesis was the first attempt to explain obesity as a consequence of adaptive responses to an ancient environment that in modern society become disadvantageous. The idea is that genes (or more precisely, alleles) predisposing to obesity may have been selected for by repeated exposure to famines. However, this idea has many flaws: for instance, selection of the supposed magnitude over the duration of human evolution would fix any thrifty alleles (famines kill the old and young, not the obese) and there is no evidence that hunter-gatherer populations become obese between famines. An alternative idea (called thrifty late) is that selection in famines has only happened since the agricultural revolution. However, this is inconsistent with the absence of strong signatures of selection at single nucleotide polymorphisms linked to obesity. In parallel to discussions about the origin of obesity, there has been much debate regarding the regulation of body weight. There are three basic models: the setpoint, settling point and dual-intervention point models. Selection might act against low and high levels of adiposity because food unpredictability and the risk of starvation selects against low adiposity whereas the risk of predation selects against high adiposity. Although evidence for the latter is quite strong, evidence for the former is relatively weak. The release from predation ∼2-million years ago is suggested to have led to the upper intervention point drifting in evolutionary time, leading to the modern distribution of obesity: the drifty gene hypothesis. Recent critiques of the dual-intervention point/ drifty gene idea are flawed and inconsistent with known aspects of energy balance physiology. Here, I present a new formulation of the dual-intervention point model. This model includes the novel suggestion that food unpredictability and starvation are insignificant factors driving fat storage, and that the main force driving up fat storage is the risk of disease and the need to survive periods of pathogen-induced anorexia. This model shows why two independent intervention points are more likely to evolve than a single set point. The molecular basis of the lower intervention point is likely based around the leptin pathway signalling. Determining the molecular basis of the upper intervention point is a crucial key target for future obesity research. A potential definitive test to separate the different models is also described.

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“…It remains unclear if lighter birds are more vulnerable to the predators as a function of their reduced vigilance owing to their need for increased food intake (cf. Gosler et al 1995;Lilliendahl 1997;Fransson and Weber 1997) and slower response times to predators (Jones et al 2009). Even though Barbary Falcons have not been reported to scavenge or feed on carrion, it is possible that some of the lightest birds died prior to being collected by the falcons.…”

Section: Discussionmentioning

confidence: 99%

“…The body mass gained or maintained is considered to be the result of the trade-off between the risks of starvation and being unable to continue or complete the migration, and predation (e.g., Gosler et al 1995;Lilliendahl 1997;Fransson and Weber 1997;Swaddle and Lockwood 1998;Burns 2003). Theoretically, heavier birds should be less adept at escaping predators (Hedenström 1992); and experimental evidence has shown that flight performance is impaired in heavier birds (e.g., Witter et al 1994;Kullberg et al 1996;Lind et al 1999).…”

Section: Introductionmentioning

confidence: 99%

“…Witter and Cuthill (1993) suggested that increased predation may not only be due to increased body mass, but also due to increased foraging rates resulting in reduced vigilance, thus increasing vulnerability to predation. Evidence from field studies shows that prey species have lower body mass during periods of high predation (Gosler et al 1995) or in response to a perceived predation risk (Lilliendahl 1997;Fransson and Weber 1997). On the other hand, experimental study by Jones et al (2009) suggests that heavier birds allocate more attention to antipredator behaviour by modifying interscan intervals, resulting in faster response times to a predator.…”

Section: Introductionmentioning

confidence: 99%

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Predation of migratory Little Stint (Calidris minuta) by Barbary Falcon (Falco pelegrinoides) is dependent on body mass and duration of stopover time

Yosef

Gołdyn

Zduniak

2010

J Ethol

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Shorebird (Charadriiformes) migration phenology is critically synchronised with prey availability at traditional staging sites that allows the birds to stage and complete the migrations. These stopovers, usually in large concentrations, make the migrants vulnerable to local predators. The body mass gained or maintained is considered to be the result of the trade-off between the risks of starvation and predation. Theoretically, heavier birds should be less adept at escaping predators, and experimental evidence showed that flight performance is impaired in heavier birds. During three migration seasons we searched pellets and prey remains taken by a pair of Barbary Falcons (Falco pelegrinoides). We discovered that many pellets contained rings from the ringing program in Eilat, Israel, and the overwhelming majority belonged to Little Stints (Calidris minuta). We checked if the body mass and length of the stopover as expressed by ringing status of the Little Stints in a particular migration season was related to the risk of predation by Barbary Falcons. We found the chance that a heavier bird would be predated was lower than that of a lighter individual, and that Stints retrapped during the same migration season were significantly more endangered by predation than those recorded only once.

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The effect of predator presence on body mass in captive greenfinches

Cited by 91 publications

References 23 publications

Separating the effects of predation risk and interrupted foraging upon mass changes in the blue titParus caeruleus

Separating the effects of predation risk and interrupted foraging upon mass changes in the blue titParus caeruleus

The evolution of body fatness: trading off disease and predation risk

Predation of migratory Little Stint (Calidris minuta) by Barbary Falcon (Falco pelegrinoides) is dependent on body mass and duration of stopover time

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