Costs, benefits, and fitness consequences of different migratory strategies

Alves, José A.; Gunnarsson, Tómas G.; Hayhow, Daniel B.; Appleton, Graham F.; Potts, Peter M.; Sutherland, William J.; Gill, Jennifer A.

doi:10.1890/12-0737.1

Cited by 114 publications

(141 citation statements)

References 31 publications

(55 reference statements)

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“…While occupancy of different kinds of non-breeding habitat has measurable effects on body condition and population growth rate in migratory birds (Marra & Holmes, 2001;Norris et al, 2004;Norris, 2005;Alves et al, 2013), it remains unknown whether pulses in habitat availability translate into population level effects that when absent or changed result in declining populations. Improving understandings of how migratory populations respond to pulses in resource availability will allow determination of how variation in the magnitude, duration and frequency of fluctuations in resource availability affect animal population sizes.…”

Section: Australian Shorebird Conservation Overviewmentioning

confidence: 99%

“…Evidence is mounting that both recruitment and mortality can be impacted by conditions at non-breeding areas for long-distance migrants (Alves et al 2013;Marra and Holmes 2001;Norris et al 2004). For example, in migratory American Redstarts, reproductive success in North America was related to the condition of non-breeding habitat in South America (Norris et al 2004).…”

Section: ) For Migratory Shorebirds Which Facultatively Use Tempmentioning

confidence: 99%

“…In nonbreeding Common Redshanks Tringa totanus in the United Kingdom showed reduced weight and a 44% increase in mortality after being displaced by the destruction of intertidal habitat used by the birds in winter . In West Africa, population declines in wintering Common Migratory shorebirds experience different energetic costs and gains in different nonbreeding habitats often due to temperature and food availability (Colwell 2010;Piersma and Lindstrom 2004) which have increasingly been related to survival rates and breeding success in the following year (Aharon-Rotman et al 2016;Alves et al 2013;Baker et al 2004;McGowan et al 2011). Studies have generally focused on the impacts of variation in habitat quality in areas that tend to be used regularly, but inland Australia is unusual in that up to 20% of a species population can occur at one lake in only one of thirty years (Kingsford and Norman 2002).…”

Section: ) For Migratory Shorebirds Which Facultatively Use Tempmentioning

confidence: 99%

“…Recent modelling suggests that failure to maintain good conditions for shorebirds at the non-breeding areas could have drastic impacts on survival and reproductive success (Aharon-Rotman et al, 2016). Such interactions between conditions in distant geographic areas impacting the same migratory species populations are increasingly being documented (Marra et al, 1998;Norris et al, 2004;Gunnarsson et al, 2005;Alves et al, 2013;van Gils et al, 2016).…”

Section: Conserving Migratory Shorebirdsmentioning

confidence: 99%

“…Indeed, recent studies have highlighted the potential effect of loss of non-breeding habitat on migratory bird populations (Norris et al, 2004;Norris, 2005;Alves et al, 2013). Some of the local effects that could be contributing to declines in shorebird population in Australia include diminishing food supply (Baker et al, 2004), a loss of adequate roosting sites (Rogers et al, 2006b), additional local habitat loss , predation by raptors (Cresswell & Whitfield, 1994;Van Den Hout et al, 2008) and disturbance (Colwell, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Ecology and conservation of Australia’s shorebirds

Clemens¹

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Global biodiversity continues to decline rapidly, and addressing this situation requires an understanding of both the problems and the solutions. This understanding is urgently required for animals occupying wetlands, among the most threatened of all habitats globally. In this thesis I focus on the ecology and conservation of shorebirds, a group comprising many threatened and declining species dependent on wetlands throughout much of their annual cycle. I focus on threats operating within Australia, where wetland loss and degradation continues due to human activity. Non-migratory shorebird species that travel widely across Australia's inland wetlands have been reported as declining in eastern Australia, but a national assessment is lacking. Migratory shorebird species that visit Australia from breeding grounds overseas appear to be declining most due to factors beyond Australia's borders, but it is not clear if threats located in Australia are exacerbating these declines. I make the most of the rich data available on shorebirds in Australia to address these knowledge gaps, in the hopes of better targeting shorebird conservation actions in Australia.In chapter one I introduce the importance of conserving migratory and highly mobile species.I then review how pulses in resource availability such as those exemplified by Australia's ephemeral wetlands impact wildlife populations. I also provide an overview of shorebird conservation in Australia. These introductions provide the theoretical underpinning for the work presented later, and highlight the challenges inherent in understanding where and when highly mobile species such as shorebirds have been impacted.In chapter two I show the benefits of applying a consistent approach to setting boundaries around areas used by migratory shorebirds during the non-breeding season. One of the first steps in identifying where conservation actions are needed for highly mobile species is defining the boundaries of management units where actions can be targeted, and which define the optimal scale for monitoring. I achieved this step by using expert knowledge to define the extent of area being used by the same local population of non-breeding shorebirds. These improved boundaries were at times very different to boundaries identified originally.In chapter three I analyse available Australian shorebird count data from many areas to determine if spatial variation in shorebird trends relates to local threats. I confirm Australia wide declines in a number of shorebird species, and add a few more to the list of shorebird species showing continental scale declines. I further show that declines are often greater in the south, but find substantial interspecific variation in trends with both latitude and 3 longitude. This suggests large scale patterns in the declines are not explained by local factors.For resident shorebirds I find rates of decline greater at non-tidal wetlands threatened by inappropriate water levels, while local threats do not appear to explain rates of decline in mi...

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Section: Australian Shorebird Conservation Overviewmentioning

confidence: 99%

Section: ) For Migratory Shorebirds Which Facultatively Use Tempmentioning

confidence: 99%

Section: ) For Migratory Shorebirds Which Facultatively Use Tempmentioning

confidence: 99%

Section: Conserving Migratory Shorebirdsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ecology and conservation of Australia’s shorebirds

Clemens¹

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Longer migration not necessarily the costliest strategy for migrating humpback whales

Riekkola

Andrews‐Goff

Friedlaender

et al. 2020

Aquatic Conservation

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Long‐distance migration is a demanding physical activity, and how well animals manage the associated costs will have important implications for their fitness. The Oceania humpback whale (Megaptera novaeangliae) population is recovering from past exploitation markedly slower than the neighbouring east Australian whales. The reasons for this are unknown, although higher energetic costs of longer migratory distances could be a possible explanation. Due to their fully aquatic lives, studying the energy expenditure of these large animals requires methods that do not rely on capturing the animal, such as bioenergetic models. A state‐space model was fitted to satellite data to infer behavioural states for southern migrating whales. Travel speeds and behavioural states were used in a bioenergetic model to estimate the energetic cost of the migration phase. Relative differences in average duration, distance, and energetic costs were compared between migratory routes and distances. Total energy used during migration was a trade‐off between cost of transport (determined by travel speed) and daily maintenance (determined by daily basal metabolic costs). Oceania whales migrating to the Amundsen and Bellingshausen Seas travelled fastest and furthest, 15 and 21% further than whales migrating to the d'Urville Sea (east Australian whales) and Ross Sea, respectively. Therefore, they had the highest cost of transport, 25 and 85% higher than for d'Urville Sea and Ross Sea whales, respectively. However, energy saved in terms of daily maintenance by using fewer days to complete a longer migration resulted in only a 6–7% increase in total energetic cost. The results highlight that travelling further does not necessarily translate into an increase in total energy expenditure for migratory whales, since they can compensate for longer distance by travelling faster. Further research on the energetics of different whale populations could provide insight into the productivity of Southern Ocean feeding regions and help understand the environmental and anthropogenic effects on the whales' energy budgets.

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Sex‐specific winter distribution in a sexually dimorphic shorebird is explained by resource partitioning

Duijns

Gils

Spaans

et al. 2014

Ecology and Evolution

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Sexual size dimorphism (SSD) implies correlated differences in energetic requirements and feeding opportunities, such that sexes will face different trade-offs in habitat selection. In seasonal migrants, this could result in a differential spatial distribution across the wintering range. To identify the ecological causes of sexual spatial segregation, we studied a sexually dimorphic shorebird, the bar-tailed godwit Limosa lapponica, in which females have a larger body and a longer bill than males. With respect to the trade-offs that these migratory shorebirds experience in their choice of wintering area, northern and colder wintering sites have the benefit of being closer to the Arctic breeding grounds. According to Bergmann's rule, the larger females should incur lower energetic costs per unit of body mass over males, helping them to winter in the cold. However, as the sexes have rather different bill lengths, differences in sex-specific wintering sites could also be due to the vertical distribution of their buried prey, that is, resource partitioning. Here, in a comparison between six main intertidal wintering areas across the entire winter range of the lapponica subspecies in northwest Europe, we show that the percentage of females between sites was not correlated with the cost of wintering, but was positively correlated with the biomass in the bottom layer and negatively with the biomass in the top layer. We conclude that resource partitioning, rather than relative expenditure advantages, best explains the differential spatial distribution of male and female bar-tailed godwits across northwest Europe.

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Costs, benefits, and fitness consequences of different migratory strategies

Cited by 114 publications

References 31 publications

Ecology and conservation of Australia’s shorebirds

Ecology and conservation of Australia’s shorebirds

Longer migration not necessarily the costliest strategy for migrating humpback whales

Sex‐specific winter distribution in a sexually dimorphic shorebird is explained by resource partitioning

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