Foraging strategies and prey encounter rate of free-ranging Little Penguins

2006 ◽  
Vol 149 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Yan Ropert-Coudert ◽  
Akiko Kato ◽  
Rory P. Wilson ◽  
Belinda Cannell
Keyword(s):  
Foraging Strategies ◽  
Encounter Rate ◽  
Free Ranging

Influence of trawling on the behaviour and spatial distribution of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in Moreton Bay, Australia

2003 ◽  
Vol 81 (12) ◽  
pp. 1947-1955 ◽  
Author(s):  
B Louise Chilvers ◽  
Peter J Corkeron ◽  
Marji L Puotinen
Keyword(s):  
Spatial Distribution ◽  
Bottlenose Dolphins ◽  
Geographical Information ◽  
Foraging Strategies ◽  
Tursiops Aduncus ◽  
Moreton Bay ◽  
Spatial Use ◽  
Free Ranging ◽  
Marine Wildlife ◽  
Southeast Queensland

Sympatric communities of inshore Indo-Pacific bottlenose dolphins (Tursiops aduncus) have previously been identified within Moreton Bay, southeast Queensland, Australia. The two communities overlap in distribution, yet are almost completely socially segregated and forage in distinctly different ways. The correlation between this social segregation, the different foraging strategies, and a human activity (trawling) has previously been demonstrated. This paper investigates the possible effects of trawling on the behaviour and spatial distribution of these two communities. A geographical information system is used to determine the spatial use of each community. The behavioural budgets of both communities showed significantly higher levels of foraging behaviours than reported for most other bottlenose dolphin communities. The spatial use of both communities changed seasonally. These results provide further detail on how human activities may indirectly influence the behaviour and spatial use of free-ranging marine wildlife.

scholarly journals The multidimensional nutritional niche of fungus-cultivar provisioning in free-ranging colonies of a neotropical leafcutter ant

2021 ◽  
Author(s):  
Antonin J.J. Crumière ◽  
Aidan James ◽  
Pol Lannes ◽  
Sophie Mallett ◽  
Anders Michelsen ◽  
...  
Keyword(s):  
Large Scale ◽  
Foraging Strategies ◽  
Generalist Herbivore ◽  
Leafcutter Ants ◽  
Microbial Symbiont ◽  
Foraging Niche ◽  
Generalist Insect ◽  
Atta Colombica ◽  
Free Ranging

AbstractThe foraging trails of Atta leafcutter colonies are among the most iconic scenes in Neotropical ecosystems, with thousands of ants carrying freshly cut plant fragments back to their nests where they are used to provision a fungal food crop. We tested a hypothesis that the fungal cultivar’s multidimensional requirements for macronutrients (protein and carbohydrates) and minerals (Al, Ca, Cu, Fe, K, Mg, Mn, Na, P and Zn) govern the foraging breadth of Atta colombica leafcutter ants in a Panamanian rainforest. Analyses of freshly cut plant fragments carried by leafcutter foragers showed that the combination of fruits, flowers, and leaves provide for a broad realized nutritional niche that can maximize cultivar’s performance. And, while the leaves that comprised the most harvested resource also delivered an intake target containing protein in excess of the amounts that can maximize cultivar growth, in vitro experiments showed that the minerals P, Al, and Fe can enhance the cultivar’s tolerance to protein-biased substrates, and potentially expand the ants’ foraging niche. Yet, the cultivar also exhibits narrow margins between mineral limitation and toxicity that may render plant fragments with seemingly optimal blends of macronutrients unsuitable for provisioning. Our approach highlights that optimal foraging is inherently multidimensional and links the foraging behavior of a generalist insect herbivore to the fundamental nutritional niche of its microbial symbiont.Significance StatementColonies of Atta colombica leafcutter ants can contain millions of specialized workers exhibiting large-scale generalist herbivory. Yet, this generalist foraging niche also depends on the poorly understood physiological needs of the ants’ domesticated fungal cultivar. We show the cultivar’s fundamental nutritional niche is broad for carbohydrates but narrower for protein and a suite of minerals, but that the cultivar’s sensitivity to excess protein is also mediated by Al, Fe, and P. More generally, this study decouples the multidimensional foraging strategies that enable a generalist herbivore to navigate a complex nutritional landscape and mix many imbalanced foods to achieve balanced cultivar provisioning.

scholarly journals Recently-adopted foraging strategies constrain early chick development in a coastal breeding gull

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7250 ◽  
Author(s):  
Alejandro Sotillo ◽  
Jan M. Baert ◽  
Wendt Müller ◽  
Eric W.M. Stienen ◽  
Amadeu M.V.M. Soares ◽  
...  
Keyword(s):  
Urban Environments ◽  
Food Sources ◽  
Foraging Strategies ◽  
Feeding Strategies ◽  
Food Quantity ◽  
Larus Fuscus ◽  
Chick Development ◽  
Foraging Niche ◽  
Anthropogenic Food Sources ◽  
Free Ranging

Human-mediated food sources offer possibilities for novel foraging strategies by opportunistic species. Yet, relative costs and benefits of alternative foraging strategies vary with the abundance, accessibility, predictability and nutritional value of anthropogenic food sources. The extent to which such strategies may ultimately alter fitness, can have important consequences for long-term population dynamics. Here, we studied the relationships between parental diet and early development in free-ranging, cross-fostered chicks and in captive-held, hand-raised chicks of Lesser Black-backed Gulls (Larus fuscus) breeding along the Belgian coast. This traditionally marine and intertidal foraging species is now increasingly taking advantage of human activities by foraging on terrestrial food sources in agricultural and urban environments. In accordance with such behavior, the proportion of terrestrial food in the diet of free-ranging chicks ranged between 4% and 80%, and consistent stable isotope signatures between age classes indicated that this variation was mainly due to between-parent variation in feeding strategies. A stronger terrestrial food signature in free-ranging chicks corresponded with slower chick development. However, no consistent differences in chick development were found when contrasting terrestrial and marine diets were provided ad libitum to hand-raised chicks. Results of this study hence suggest that terrestrial diets may lower reproductive success due to limitations in food quantity, rather than quality. Recent foraging niche expansion toward terrestrial resources may thus constitute a suboptimal alternative strategy to marine foraging for breeding Lesser Black-backed Gulls during the chick-rearing period.

Foraging strategies of sympatric lagomorphs: implications for differential success in fragmented landscapes

2000 ◽  
Vol 78 (12) ◽  
pp. 2134-2141 ◽  
Author(s):  
Douglas F Smith ◽  
John A Litvaitis
Keyword(s):  
New England ◽  
Foraging Strategies ◽  
Fragmented Landscape ◽  
Sylvilagus Floridanus ◽  
High Quality ◽  
Fragmented Landscapes ◽  
Sylvilagus Transitionalis ◽  
Quality Food ◽  
Close Proximity ◽  
Free Ranging

In recent decades, the distribution of New England cottontails (Sylvilagus transitionalis) has declined substantially in response to forest maturation and fragmentation. Populations of eastern cottontails (Sylvilagus floridanus) have expanded into the range of S. transitionalis, since they are apparently less affected by the consequences of habitat modifications. We suspected that S. floridanus was able to exploit small patches of habitat where S. transitionalis was vulnerable to intense predation and we evaluated this explanation using large enclosures within which we manipulated the quality and distribution of food in relation to escape cover. In trials with low-quality food in cover and high-quality food in open areas, S. transitionalis sacrificed food quality for safety by remaining in close proximity to cover. Sylvilagus floridanus avoided low-quality food in cover and foraged at sites containing high-quality food away from cover. When food was removed from cover, S. transitionalis was reluctant to forage in the open and lost a greater proportion of body mass and succumbed to higher rates of predation than did S. floridanus. We applied these results to patterns of foraging by free-ranging rabbits in a fragmented landscape and estimated that S. transitionalis could successfully exploit only 32% of the available habitat without experiencing elevated rates of predation, whereas S. floridanus could exploit 99% of the habitat. Thus, the consequences of habitat fragmentation (especially higher predation risk) may not be as detrimental to S. floridanus, and this species will likely persist, whereas populations of S. transitionalis will continue to decline.

Testing predictions of optimal diving theory using animal-borne video from harbour seals (Phoca vitulina concolor)

2014 ◽  
Vol 92 (4) ◽  
pp. 309-318 ◽  
Author(s):  
Susan G. Heaslip ◽  
W. Don Bowen ◽  
Sara J. Iverson
Keyword(s):  
Nova Scotia ◽  
Temporal Pattern ◽  
Dive Depth ◽  
Dive Duration ◽  
Phoca Vitulina ◽  
Encounter Rate ◽  
Harbour Seals ◽  
Wide Range ◽  
Oxygen Stores ◽  
Free Ranging

Optimal diving theory predicts that animals make decisions that maximize their foraging profitability subject to the constraint of oxygen stores. We examined the temporal pattern of prey encounters within a dive from concurrently collected dive data and animal-borne video from a free-ranging pinniped to test predictions of optimal diving theory. Crittercams were deployed on 32 adult male harbour seals (Phoca vitulina concolor De Kay, 1842) at Sable Island, Nova Scotia, Canada, for 3 days each. Deployments resulted in approximately 3 h of video per seal and a total of 2275 capture attempts for 1474 prey encounter events recorded. We found support for seven of the nine selected predictions of optimal diving theory. As predicted, prey encounters increased with bottom duration; dive duration increased with dive depth; and travel duration, bottom duration, and percent bottom duration decreased over a wide range of travel durations. Descent duration did increase with dive depth, and seals terminated dives earlier when no prey were encountered and when prey were encountered later in a dive. Contrary to prediction, bottom duration did not increase and then decrease for short travel durations and dives were not terminated earlier when travel durations were short and prey encounter rate was low.

Weddell seal foraging dives: comparison of free-ranging and isolated-hole paradigms

2014 ◽  
Vol 27 (1) ◽  
pp. 57-68 ◽  
Author(s):  
K.M. Madden ◽  
L.A. Fuiman ◽  
T.M. Williams ◽  
R.W. Davis
Keyword(s):  
Foraging Behaviour ◽  
Three Dimensional ◽  
Foraging Strategy ◽  
Weddell Seal ◽  
Foraging Strategies ◽  
Weddell Seals ◽  
Complex Interactions ◽  
Behaviour Changes ◽  
Free Ranging ◽  
Multiple Holes

AbstractWeddell seals are polar predators that must partition their time between many behaviours, including hunting prey at depth and breathing at the surface. Although they have been well studied, little is known about how foraging behaviour changes when access to breathing holes is restricted, such as in the isolated-hole paradigm. The current study took advantage of previously gathered data for seals diving at an isolated hole to compare with foraging behaviour of free-ranging seals that had access to multiple holes. We examined dive structure, hunting tactics, and allocation of time, locomotor activity and energy based on three-dimensional dive profiles and video imagery of prey encounters for two free-ranging and six isolated-hole seals. Midsummer foraging dives of free-ranging seals were remarkably similar to those of seals diving at an isolated hole, but there were differences in two behavioural states and the frequency of several behavioural transitions. Results indicate that seals employ an energetically more conservative foraging strategy when access to breathing holes is limited and prey are less abundant. These results highlight the importance of understanding the complex interactions between breathing hole access, prey abundance and other factors that may result in different Weddell seal foraging strategies under changing future conditions.

scholarly journals South for the winter? Within‐dive foraging effort reveals the trade‐offs between divergent foraging strategies in a free‐ranging predator

2016 ◽  
Vol 30 (10) ◽  
pp. 1623-1637 ◽  
Author(s):  
Benjamin Arthur ◽  
Mark Hindell ◽  
Marthan N. Bester ◽  
W. Chris Oosthuizen ◽  
Mia Wege ◽  
...  
Keyword(s):  
Foraging Strategies ◽  
Foraging Effort ◽  
Trade Offs ◽  
Free Ranging
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