Foraging Ecology Of Winter Breeding Seabirds In New Zealand
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Foraging Ecology Of Winter Breeding Seabirds In New Zealand
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Author : Timothée Poupart
language : en
Publisher:
Release Date : 2019
Foraging Ecology Of Winter Breeding Seabirds In New Zealand written by Timothée Poupart and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
Although the cost of reproduction constrains animals to breed during spring/summer when food availability peaks, exception exist in seabirds with few species engaged in breeding during winter months. How their elevated energy needs can be sustained during a period traditionally reported for food shortage and challenging at-sea conditions is poorly understood. In addition, this unusual breeding phenology is adopted by more species in New Zealand than elsewhere in the world, with a concentration on the South island west coast where several winter breeding species are reported to forage with overlap. Therefore, the objectives of this thesis were to: 1) describe the fine-scale foraging behaviour of winter-breeding species from the west coast of New Zealand's South Island, 2) investigate the intrinsic and extrinsic factors driving their foraging, and 3) quantify their niche overlap as they exploit similar areas during elevated energetically demand. Using bio-logging data (GPS, accelerometer, dive recorder) combined with stable isotopes (carbon and nitrogen from whole blood), the winter foraging strategies of breeding males and females were investigated in a deep diver (Fiordland penguin Eudyptes pachyrhynchus) and two surface-feeders / shallow divers (Westland petrel Procellaria westlandica and southern Buller's albatross Thalassarche b. bulleri). The tracked individuals foraged close to their colony compared to their summer breeding congenerics, using primarily the nearby shelf-slope and neritic waters. Males and females displayed similar foraging behaviour in penguins and petrels, while spatial sexual differences occurred for albatross. All three species encountered prey at a high rate, allowing raising offspring with good success and without higher foraging effort than their summer-breeding congeners.These findings suggest that winter-breeding species have a phenology matching a winter prey resource on the shelf of the west coast of New Zealand's South Island. With additional data from literature for little penguin Eudyptula minor and spotted shag Stictocarbo punctatus, this winter-breeding community showed partial overlap of their foraging niche, but an accumulation of small divergences in home ranges, diving behaviour, temporal pattern of foraging, diet and trophic level is likely to explain their coexistence. Hence, winter-breeding can be a favourable phenology for high-level predators, which exploit shelf-slope and inshore waters undergoing winter mixing that insure fish and squids persistence through winter. In addition, winter-breeding also allow the matching of chick-fledging period with the spring (local primary production peak), and before the elevated needs of millions of summer-breeding species back from migration.
Foraging And Breeding Ecology Of The Australasian Gannet Morus Serrator With Applications For Rare New Zealand Seabirds
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Author : Stephanie M. H. Ismar
language : en
Publisher:
Release Date : 2010
Foraging And Breeding Ecology Of The Australasian Gannet Morus Serrator With Applications For Rare New Zealand Seabirds written by Stephanie M. H. Ismar and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Cape Kidnappers Gannet Reserve (N.Z.) categories.
"The foraging ecology and breeding phenology in seabirds are strongly linked, as their reproductive success is critically dependent on food availability. The prey of these marine top-predators is highly patchily distributed in time and space and accordingly breeding success is extremely variable between years. The sex-specificity of breeding behaviours, parental care roles, and foraging strategies, as well as subtle forms of sexual dimorphism, yet warrant investigation particularly in many size-monomorphic taxa amongst the typically obligately biparental seabird species. I employed molecular sexing, extensive field observation, spectrophotometry, visual modeling, and stable isotope analyses, and deployed geolocation sensors, Argos satellite devices, and depth gauges to assess sex-specificity of phenotype, mate retention, parental care roles, and foraging parameters, and their implications for reproductive success in the Australasian gannet Morus serrator at Cape Kidnappers gannetry, Hawkes Bay. I also applied some of these methods to small breeding populations of other seabird taxa on the Kermadec Islands, capturing an example of rare natural re-colonisation of the recently predator-free Raoul by black-winged petrels Pterodroma nigripennis and monitoring offspring sex-ratio in these growing populations. I additionally illustratively applied the methods refined in the study of M. serrator to the assessment of potential sexual dimorphism in red-tailed tropicbirds Phaethon rubricauda and masked boobies Sula dactylatra, breeding on the Kermadec Islands. This thesis reports sexual dichromatism together with a high degree of size-monomorphism in the Australasian gannet, with the exception of a subtle, but significant size-dimorphism in bill size. While showing that mate retention in this species entails higher reproductive success, I report an annual divorce rate of ~40%. I show that early-season territorial establishment is male-accrued, and that early arrival to the breeding site is linked with a reproductive advantage for male, but not for female Australasian gannets. Furthermore, nest material provisioning is shown to be a male-accrued task, and to entail a thermal benefit for incubating gannets. My findings uncover that males contribute higher parental investment during incubation, while females display increased foraging effort and distinct diet targeting during these early breeding stages. I further present first tracking results depicting migration of fledgling and adult Australasian gannets to Australian waters, with a realized post-fledging flight path over Stewart Island which minimizes the distance traveled across open water, while adult migration routes appear more plastic. I detect a significant male offspring bias in black-winged petrel populations under low competitive constraint. I also describe the extent of sexual size-dimorphism in Kermadec breeding populations of the red-tailed tropicbird and the masked booby. This dissertation includes a general review of the research field with an introduction to the study species and sites, stating my specific contributions to the following data chapters. A general discussion summarizing the main findings, evaluating these in the light of sexual and natural selection on sexual dimorphism and sex-specific behaviour in sulid seabirds, and suggesting further research and implications for seabird conservation concludes the thesis"--Abstract.
The Foraging And Reproductive Ecology Of A Resident Inshore Seabird The Little Penguin
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Author : Nicole Daniela Kowalczyk
language : en
Publisher:
Release Date : 2015
The Foraging And Reproductive Ecology Of A Resident Inshore Seabird The Little Penguin written by Nicole Daniela Kowalczyk and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with Little blue penguin categories.
Coastal and inshore, resident seabirds forage in close proximity to their breeding colonies year-round. Compared to offshore and pelagic seabirds that can travel widely in search of adequate resources, inshore residents rely on locally abundant prey stocks, making them particularly vulnerable to shifts in prey availability and distribution. Relatively few studies have assessed how these seabirds are equipped to deal with environmental variability and fluctuations in their local resources. These knowledge gaps hamper the effective management and conservation of their habitat resources and prey, and limit our ability to predict how seabirds will respond to shifts in prey availability. Using the St Kilda little penguin (Eudyptula minor) colony as a model species, this thesis addressed knowledge gaps in the foraging and reproductive ecology of inshore, resident seabirds. Stable isotope analyses in combination with previously published records of stomach content data were used to reconstruct the diet of little penguins during the breeding and non-breeding season over four years. This examination confirmed that little penguins are generalist predators that forage opportunistically within Port Phillip Bay, on a predominantly anchovy (Engraulis australis) based diet. The study found that during the breeding season, penguins exploit prey species that enter the bay from offshore waters to spawn and during the non-breeding season, penguins exploit juvenile fish communities, which use the bay as a nursery and dominate the prey biomass in the winter months. Due to this continuous supply of prey, combined with the opportunistic foraging strategies of little penguins, St Kilda penguins can remain in the bay year-round. GPS analysis combined with environmental data was then used to determine penguin foraging habitat preferences in the bay. This investigation found penguins predominantly occurred in productive waters, with low turbidity. These findings indicate inshore residents maximise net energy gain by foraging opportunistically, within oceanographic features with enhanced productivity that aggregate prey and facilitate prey capture. Fish stock assessments in the bay conducted by Government Agencies between years 2007 and 2011, provided an independent and unique dataset to assess penguin diet preference. The fish stock assessment demonstrated substantial inter-annual fluctuations in clupeoid (including anchovy) abundance and diversity. I sought to assess the foraging and reproductive responses of this inshore resident to shifts in prey availability, by monitoring their foraging behaviour (GPS analysis), diet (stable isotope analysis) and reproductive parameters (hatching success, fledging success, annual reproductive success, chick growth). GPS and stable isotope results demonstrated little penguins were able to accommodate fluctuations in resources by modifying their foraging distribution and dietary niche to maximise energy intake. Specifically, penguins modified their foraging ranges to track shifts in prey distribution. In terms of diet, penguins opportunistically modified their dietary breadth to maximise resource intake. Despite their high degree of foraging and dietary plasticity, measures of penguin breeding performance varied substantially from year to year. These variations in breeding performance were attributed to inter-annual fluctuations in prey abundance and composition; when resource availability was poor, breeding activities were delayed, and penguins had low hatching success, fledging success, and low overall annual reproductive success. When resources were abundant, breeding commenced early in the year, and penguins had high hatching and fledging success, laid double broods, which led to high annual reproductive success. These findings indicate that when resources are scarce, like other long-lived seabird species, little penguins prioritise their own condition at the expense of their young, as a means to increase their life-time reproductive success. This study also found that peak chick mass did not differ in contrasting resource conditions, which suggests that in a given clutch, parents favour rearing a single chick of good condition over rearing multiple chicks of poor condition. Rearing a chick of good condition is expected considering that peak and fledging body mass are critical determinants of first year survival. By investing in a single healthy chick over two chicks of poor condition adults ultimately increase their fitness. The year-round availability of prey in the bay and the relatively short foraging range of little penguins means they can remain within close proximity to their breeding area at all stages of the annual cycle. This may have energetic benefits that ultimately improve their long-term reproductive success. However, this limited foraging range may also make them vulnerable to resource fluctuations in their local range. Thus, the continued monitoring of their foraging and reproductive ecology will be central to ensuring the ongoing viability of this urban, inshore, resident seabird species.
Foraging Ecology Of Breeding Seabirds In Greenland
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Author : Jannie Fries Linnebjerg
language : en
Publisher:
Release Date : 2012
Foraging Ecology Of Breeding Seabirds In Greenland written by Jannie Fries Linnebjerg and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Sea birds categories.
Sex Specific Foraging Behaviour By A Low Arctic Diving Seabird Over The Annual Cycle
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Author : Chantelle M. Burke
language : en
Publisher:
Release Date : 2021
Sex Specific Foraging Behaviour By A Low Arctic Diving Seabird Over The Annual Cycle written by Chantelle M. Burke and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
This thesis examines the seasonal foraging ecology of the Common Murre (Uria aalge), a circumpolar seabird with physiological adaptations for efficient pursuit-diving and a specialized reproductive strategy (male-biased parental care). The primary research objectives are to assess the behavioural strategies drawn upon by adult murres to survive a seasonally dynamic, Arctic-influenced marine environment, and to investigate how seasonal differences in parental care roles influence sex-specific foraging and survival strategies. To engage this question, I use bird-borne data loggers that collect behavioural observations relating to the distribution, diving and daily activity patterns of individual murres over eight months (July - February) in their annual cycle. Behavioural metrics are integrated with analyses of stable isotope ratios from a variety of tissues that provide corresponding information on seasonal trophic position and dietary niche breadth. Murres exhibited flexibility in their foraging behaviour over the annual cycle. This was evident in a switch from increased foraging effort with a specialized, high trophic level diet during periods of peak energy demand (summer chick-rearing and late winter) to significantly reduced foraging effort and a generalized, low trophic level diet during the less demanding post-breeding period. Energy savings during moult-induced flightlessness and a flexible moult schedule facilitated by a resident, over-wintering strategy resulted in low energy demands during the post-breeding wing moult. I hypothesise that the post-breeding period represents a buffer event in the annual cycle of adult murres, and may be a key component of survival for a seabird with an otherwise costly pace of life. Single-parenting males spent twice as much time foraging (self and offspring provisioning) relative to independent females (self provisioning only) and occupied relatively poor quality habitat over the estimated 63 days of paternal care at sea. Despite this, there was no evidence of an energy constraint as single-parenting males consumed the same low trophic-level diet as independent females and allocated equivalent time to self-feeding. Nonetheless, adult males could face time constraints to rear their offspring to independence and complete post-breeding wing moult before the onset of winter if energy limitations during poor-food years are resolved by the extension of either (or both) fitness-related activities. During late winter, murres experienced a significant increase in estimated daily energy expenditures (DEE), driven in part by high thermoregulatory costs during prolonged exposure to cold water. Murres were able to overcome this energetic challenge by pushing the limits of their diving capabilities but regardless, late winter appears to be an extremely challenging time in their annual cycle. Overall, this thesis demonstrates remarkable behavioural plasticity by murres over their annual cycle, characterized by highly plastic foraging tactics, dietary strategies and flexibility in the scheduling of wing moult, which may allow them to mediate some of the environmental disruptions predicted to occur with climate change. Yet, persistent declines in the biomass and condition of capelin Mallotus villosus, the keystone forage species in the NW Atlantic food web and the primary prey of breeding murres (and their offspring) could challenge this resiliency.
Variability In Foraging Ecology And Food Consumption By Seabirds At High Latitudes
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Author : Eric J. Woehler
language : en
Publisher:
Release Date : 1995
Variability In Foraging Ecology And Food Consumption By Seabirds At High Latitudes written by Eric J. Woehler and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Fork-tailed storm petrel categories.
New Zealand Journal Of Zoology
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Author :
language : en
Publisher:
Release Date : 1987
New Zealand Journal Of Zoology written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with categories.
Reproductive Foraging Ecology Of Five Sympatrically Breeding Alcid Seabirds
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Author : William Eric Davies
language : en
Publisher:
Release Date : 2007
Reproductive Foraging Ecology Of Five Sympatrically Breeding Alcid Seabirds written by William Eric Davies and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with Alcidae categories.
Foraging Strategies In Seabirds During The Breeding Season
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Author : Jóhannis Danielsen
language : en
Publisher:
Release Date : 2007
Foraging Strategies In Seabirds During The Breeding Season written by Jóhannis Danielsen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007 with categories.
The Foraging Ecology Of Peruvian Seabirds
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Author : D.C. DUFFY
language : en
Publisher:
Release Date : 1983
The Foraging Ecology Of Peruvian Seabirds written by D.C. DUFFY and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with categories.