Long‐distance flights and high‐risk breeding by nomadic waterbirds on desert salt lakes

Pedler, Reece D.; Ribot, Raoul F. H.; Bennett, Andrew T. D.

doi:10.1111/cobi.13007

Cited by 23 publications

(13 citation statements)

References 36 publications

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“…Most environments, however, are neither entirely consistent nor entirely predictable, which can affect the consistency with which individuals are able to perform their migrations (e.g., Studds and Marra, 2011). In addition, an individual can exhibit different migration strategies with increasing experience (e.g., individual improvement; Sergio et al, 2014), because the environment requires flexibility (e.g., nomadism ;Pedler et al, 2018), or because the environment allows flexibility (e.g., the absence of carry-over effects; Senner et al, 2014). Differences in an individual's migratory behavior across years (i.e., intra-individual variation) therefore also contribute to migration variation at the population level (sensu Conklin et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Variation From an Unknown Source: Large Inter-individual Differences in Migrating Black-Tailed Godwits

et al. 2019

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Variation in migratory behavior is the result of different individual strategies and fluctuations in individual performances. A first step toward understanding these differences in migratory behavior among individuals is, therefore, to assess the relative contributions of inter-and intra-individual differences to this variation. We did this using light-level geolocators deployed on the breeding grounds to follow continental black-tailed godwits (Limosa limosa limosa) throughout their south-and northward migrations over multiple years. Based on repeated tracks from 36 individuals, we found two general patterns in godwit migratory behavior: First, migratory timing in black-tailed godwits varies mostly because individual godwits migrate at different times of the year. Second, individuals also exhibit considerable variation in timing within their respective migratory windows. Although the absolute amount of inter-individual variation in timing decreased over the course of northward migration, individual godwits still arrived at their breeding grounds across a span of more than 5 weeks. These differences in migratory timing among individuals are larger than those currently observed in other migratory bird species and suggest that the selective forces that limit the variation in migratory timing in other species are relaxed or absent in godwits. Furthermore, we could not attribute these individual differences to the sex or wintering location of an individual. We suggest that different developmental trajectories enabled by developmental plasticity likely result in these generally consistent, lifelong annual routines. To investigate this possibility and to gain an understanding of the different selection pressures that could be acting during migration and throughout a godwit's life, future studies should track juvenile godwits and other migratory birds from birth to adulthood while also manipulating their spatiotemporal environment during development.

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Section: Introductionmentioning

confidence: 99%

Variation From an Unknown Source: Large Inter-individual Differences in Migrating Black-Tailed Godwits

et al. 2019

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“…In some cases, individuals may vary their departure dates from non-breeding sites by as little as 3 days over 4 consecutive years (Conklin et al, 2013). In contrast, other studies have found that individuals of some species can exhibit marked improvement and flexibility in their migratory timing and performance, enabling them to adjust their behaviors to prevailing environmental conditions (Sergio et al, 2014;Pedler et al, 2018). What remains unclear, though, is how flexible migratory behaviors are generally and how both historical and contemporary selection pressures may mold the levels of flexibility exhibited by individuals within a population.…”

Section: Introductionmentioning

confidence: 99%

High Migratory Survival and Highly Variable Migratory Behavior in Black-Tailed Godwits

et al. 2019

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Few studies have been able to directly measure the seasonal survival rates of migratory species or determine how variable the timing of migration is within individuals and across populations over multiple years. As such, it remains unclear how likely migration is to affect the population dynamics of migratory species and how capable migrants may be of responding to changing environmental conditions within their lifetimes. To address these questions, we used three types of tracking devices to track individual black-tailed godwits from the nominate subspecies (Limosa limosa limosa) throughout their annual cycles for up to 5 consecutive years. We found that godwits exhibit considerable inter-and intra-individual variation in their migratory behavior across years. We also found that godwits had generally high survival rates during migration, although survival was reduced during northward flights across the Sahara Desert. These patterns differ from those observed in most other migratory species, suggesting that migration may only be truly dangerous when crossing geographic barriers that lack emergency stopover sites and that the levels of phenotypic flexibility exhibited by some populations may enable them to rapidly respond to changing environmental conditions.

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“…The high unexplained variances for the radjah shelduck, magpie goose and plumed whistling duck are likely caused by the latter, as their typical range straddles the northern boundary of EAWS survey area, with greater movement into the survey area on occasion in response to seasonal conditions. Likewise, recent studies suggest that the entire population of banded stilt can move into and out of the survey region (Pedler et al 2014(Pedler et al , 2018, which explains the high year-to-year variation in φ, including very low (and sometimes zero) counts in some years (particularly during the Millennium Drought: see Fig. 5c and Fig.…”

Section: On Explaining Variationmentioning

confidence: 80%

On inferring population trends of mobile waterbirds from aerial transect surveys in variable environments

et al. 2021

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Monitoring waterbird populations in Australia is challenging for reasons of counting logistics, and because population aggregation and dispersion can shift rapidly in response to large spatio-temporal variations in resource availability. The East Australian Waterbird survey has conducted annual, aerial, systematic counts of waterbirds over eastern Australia for almost 40 years. It was designed to monitor waterbird populations using design-based inference though for many species this form of inference appears inadequate in the face of these challenges. Here we develop a state-space model-based Bayesian approach that, in addition to explicitly incorporating process noise and observation uncertainty, uses random effects and rainfall-derived covariates to model the year-to-year variation in the proportion of the total (super) population that is present on surveyed wetlands, and available to be counted. We use this model-based approach to estimate the superpopulation size of 45 waterbird species annually, and model the rate of population increase as a function of antecedent rainfall. The results confirm the strong positive effect of antecedent rainfall on population growth rates for nearly all species, and illustrate that species respond to rainfall differently in terms of habitat use, which influences whether they are present on surveyed wetlands. For many species, the year-to-year variation in the estimated proportion of the population on surveyed wetlands is very high. The results have implications for making inferences on population trends from these data, with the ability to model the year-to-year sampling variation a key requirement before the rate of population increase can be estimated with any precision. This study illustrates how to progress this approach, and infers that under average rainfall conditions, the general trend is for estimated superpopulation rates of increase to be negative, though for only a few species is this occurring with strong belief.

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Long‐distance flights and high‐risk breeding by nomadic waterbirds on desert salt lakes

Abstract: Palabras Clave: ave acuática, ave costera, desierto, especie móvil, nomadismo

Cited by 23 publications

References 36 publications

Variation From an Unknown Source: Large Inter-individual Differences in Migrating Black-Tailed Godwits

Variation From an Unknown Source: Large Inter-individual Differences in Migrating Black-Tailed Godwits

High Migratory Survival and Highly Variable Migratory Behavior in Black-Tailed Godwits

On inferring population trends of mobile waterbirds from aerial transect surveys in variable environments

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