Foraging Blue Tits<i>Parus caeruleus</i>may trade-off calorific value of food items and distance from cover

Allen, A.J.; Harper, David G.

doi:10.1080/00063650009461178

Cited by 4 publications

(5 citation statements)

References 10 publications

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“…Thus, by changing their foraging substrate to intermediate vegetation in invaded forests, blue tits can benefit from these greater supplies to feed their nestlings. By altering food density and quality, studies into the optimal foraging strategies of passerines have demonstrated the existence of a trade-off between the risk of predation and foraging far from cover (Schneider 1984;Slotow and Paxinos 1997) and that a reduction in the quality of nutrients available in foraging sites under better cover results in an increased use of more exposed sites (Allen and Harper 2000). Thus, in invaded areas, the increased predation risk for parents coming down from their preferred strata of the canopy to the shrubs may be counterbalanced by the benefits they gain in providing for their offspring.…”

Section: Discussionmentioning

confidence: 99%

Is the blue tit falling into an ecological trap in Argentine ant invaded forests?

et al. 2013

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Because insectivorous birds must evaluate resources for reproduction before settling into a breeding habitat, they can fall into an ecological trap if informative cues about habitat suitability become dissociated from their actual yield. Given their potential to affect ecological networks, invasive ant species are potential candidates for triggering such ecological traps. We combined observational and experimental approaches to examine whether the variation in food supply for nestlings resulting from the invasion of the Argentine ant, Linepithema humile, had any influence on the breeding ecology of the blue tit, Cyanistes caeruleus, an insectivorous foliage-gleaner. We investigated the effects of the ant invasion on breeding performance (nesting success, clutch size, brood size and breeding success) and offspring quality (body size and condition, developmental stability and plumage colour) in replicated Mediterranean forest areas over a period of 3 years. There was no evidence that the reduction in caterpillar availability resulting from the invasion had a concurrent negative effect on the blue tit's ability to successfully rear nestlings in optimal conditions, at least as measured here. Although the raw figures suggest an increased level of nutritional stress in blue tits breeding in invaded forests, the data analyses showed no significant alterations in terms of productivity or offspring fitness. The reproductive performance of the blue tit has been shown to be remarkably resilient to the Argentine ant-mediated food shortage, either because the prey reduction following the invasion did not reach a critical threshold or because of compensatory activity by the progenitors. We cannot conclusively reject an ecological trap triggered by the ant invasion on blue tits, since neither fledgling recruitment nor the prospective survival of parents were assessed. Even though we could not confirm short-term consequences of the Argentine ant invasion on blue tit reproductive fitness, the long-term bottom-up effects of the invasion remain unknown and should not be ruled out.

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Section: Discussionmentioning

confidence: 99%

Is the blue tit falling into an ecological trap in Argentine ant invaded forests?

et al. 2013

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“…Model predictions are accessible to study with wild individuals foraging at feeders, and could even be explored using common garden feeders (e.g. [ 27 , 28 ]) provided a suitable technique for avoiding pseudoreplication is used. The predictions made here about behaviour in response to differing distances between the refuge and foraging site are particularly open to experimental manipulation, and broadly match existing empirical evidence (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Despite the potential ease of observing travel to a close foraging site, and the number of studies exploring this form of foraging behaviour (e.g. [11][12][13][14][15][16][17][27][28][29][40][41][42][43]), there is little empirical information about this behaviour, and that which exists (e.g. [41], which shows that several species of bird travelled directly between refuge and foraging site without stopping) is anecdotal.…”

Section: Discussionmentioning

confidence: 99%

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Leaving safety to visit a feeding site: is it optimal to hesitate while exposed?

Rands

2017

R. Soc. open sci.

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Animals living in complex environments experience differing risks of predation depending upon their location within the landscape. An animal could reduce the risk it experiences by remaining in a refuge site, but it may need to emerge from its refuge and enter more dangerous sites for feeding and other activities. Here, I consider the actions of an animal choosing to travel a short distance between a safe refuge and a dangerous foraging site, such as a bird leaving cover to visit a feeder. Although much work has been conducted examining the choice between a refuge and a foraging site when faced with a trade-off between starvation and predation risk, the work presented here is the first to consider the travel behaviour between these locations. Using state-dependent stochastic dynamic programming, I illustrate that there are several forms of optimal behaviour that can emerge. In some situations, the animal should choose to travel without stopping between sites, but in other cases, it is optimal for the animal to travel hesitantly towards the food, and to stop its travel at a point before it reaches the refuge. I discuss how this hesitant ‘dawdling’ behaviour may be optimal, and suggest further work to test these predictions.

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“…Glossy Black‐cockatoos may be at increased risk of predation when feeding in open sites (Allen & Harper 2000), and may limit the time they spend feeding in these habitats to reduce this risk. Raptors are the most identifiable threat to foraging Glossy Black‐cockatoos (Garnett et al .…”

Section: Discussionmentioning

confidence: 99%

Habitat selection at multiple spatial scales by foraging Glossy Black‐cockatoos

Cameron¹,

Cunningham²

2006

Austral Ecology

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Habitat selection among vertebrates entails decision making at a number of spatial scales. An understanding of factors influencing decisions at each of these scales is required for the effective management of wildlife populations. This study investigates the foraging ecology of a population of Glossy Black-cockatoos in central New South Wales. We took advantage of the characteristic feeding sign produced by Glossy Black-cockatoos to examine factors influencing habitat selection at multiple spatial scales. Birds preferred to forage at sites where food was abundant and avoided open sites where the predation risk may be greater. Their two food species, Allocasuarina diminuta and Allocasuarina gymnanthera, differed in profitability (kernel intake rate as measured by the ratio of seed weight to total seed and cone weight), as did trees within a species. Both species were utilized extensively, although foraging intensity was greater at sites where the more profitable species was present. In order to maximize their food intake, birds selected individual trees on the basis of cone abundance and profitability. Cones produced in the previous year were preferred.

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Foraging Blue TitsParus caeruleusmay trade-off calorific value of food items and distance from cover

Cited by 4 publications

References 10 publications

Is the blue tit falling into an ecological trap in Argentine ant invaded forests?

Is the blue tit falling into an ecological trap in Argentine ant invaded forests?

Leaving safety to visit a feeding site: is it optimal to hesitate while exposed?

Habitat selection at multiple spatial scales by foraging Glossy Black‐cockatoos

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