Abstract
Globally, bird migration is occurring earlier in the year, consistent with climate-related changes in breeding resources. Although often attributed to phenotypic plasticity, there is no ...clear demonstration of long-term population advancement in avian migration through individual plasticity. Using direct observations of bar-tailed godwits (
Limosa lapponica
) departing New Zealand on a 16,000-km journey to Alaska, we show that migration advanced by six days during 2008–2020, and that within-individual advancement was sufficient to explain this population-level change. However, in individuals tracked for the entire migration (50 total tracks of 36 individuals), earlier departure did not lead to earlier arrival or breeding in Alaska, due to prolonged stopovers in Asia. Moreover, changes in breeding-site phenology varied across Alaska, but were not reflected in within-population differences in advancement of migratory departure. We demonstrate that plastic responses can drive population-level changes in timing of long-distance migration, but also that behavioral and environmental constraints en route may yet limit adaptive responses to global change.
Tracks individual bar-tailed godwits 'Limosa lapponica baueri' for two full years (including direct observation during non-breeding seasons in New Zealand and geolocator tracking of round-trip ...migrations to Alaska) to present a full annual-cycle view of molt, breeding, and migration schedules. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.
Birds are extremely vulnerable to the effects of oil pollution. For wildlife, prevention of oiling is the best response option, however if not feasible, the fastest response gives the highest chance ...of survival. Therefore, the development of an oiled wildlife preparedness plan based on analysis of areas at risk, vulnerable species and potential response options is critical. This research developed an area based, species priority index (SPI) for New Zealand birds to guide oiled wildlife planning. The SPI shows significant areas of New Zealand's shoreline and offshore islands have many highly vulnerable species that need careful consideration given restricted response options available. Identification of these areas and species allows priority planning for placement of personal and equipment. This SPI can be adapted for other species (marine mammals and reptiles) and for other geographical areas to help develop response plans for oil pollution and oiled wildlife response worldwide.
•Birds are extremely vulnerable to the effects of oil pollution.•Prevention is best, but if not feasible, a fast response gives highest survival.•For this, an oiled wildlife plan based on risk, species and response options is critical.•We developed an area based species priority index (SPI) for New Zealand.•The SPI can be adapted for other species and oiled wildlife plans worldwide.
Many migratory birds start prebreeding moult and premigratory fuelling some months before the breeding season and face severe time constraints, while travelling up to 15 000 km between non-breeding ...and breeding grounds. Shorebirds typically leave Southern Hemisphere non-breeding areas over a 3-4 week period, but whether they benefit from interannually consistent timing of departure is unknown. Here, I show that individual bar-tailed godwits (Limosa limosa baueri) from New Zealand are highly consistent in their migratory scheduling. Most birds left within the same week each year (between-year repeatability, r, of 0.83) and adult males, which moult into a bright breeding plumage, were also highly repeatable in the extent of their prebreeding moult (r=0.86). This is consistent with the hypothesis that birds have individually optimized migration schedules. Within adult males, but not females, smaller birds tended to migrate earlier than large birds. Whether this reflects differences in size-related migration speed, optimal breeding time at different sites or size-related natural or sexual selection pressures, remains unknown.
Previous breeding-season studies of threatened New Zealand falcons (Falco novaeseelandiae) in plantation forests have suggested that falcons benefit when harvesting creates a mosaic of differently ...aged stands, especially where young and mature tree stands are adjacent. Thus, changes in the rate and pattern of harvesting may affect habitat heterogeneity by altering the size and distribution of forest patches. We sought to determine guidelines for harvesting that would most benefit falcons by increasing the carrying capacity of the forest for falcons. We used radio-tracking to determine the home-range sizes of non-breeding falcons over 3 seasons and compared winter home-range overlap in the most-selected land cover types by falcons (mature-young edges and open patches) with other land cover types. The distribution of open patches and edges between mature stands and recently cleared areas affected falcon home ranges, home-range overlap, and the likelihood of nesting. Specifically, home ranges were smaller as the density of edges and percentage of open patch increased, and there was greater home-range overlap between individuals in the most-selected land cover types. Numbers of falcons decreased as the size of open patches increased, concomitant with a decrease in edge size, the number of edge borders, and the number of open patches. The likelihood of nesting also decreased as open patch size increased. Our results indicate that smaller open patches spread through a forest, maximizing the amount of mature-young edges, will favor smaller home ranges and therefore potentially greater numbers of falcons. We recommend harvesting protocols that ensure that open patches (0–3-yr-old stands) are <4km² in size and retain at least small stands of mature pine to maintain a high density of edges. Similar protocols may increase the carrying capacity for other species occurring in managed systems involving fragmented landscapes or small reserves.
Present‐day ecology and population structure are the legacies of past climate and habitat perturbations, and this is particularly true for species that are widely distributed at high latitudes. The ...red knot, Calidris canutus, is an arctic‐breeding, long‐distance migratory shorebird with six recognized subspecies defined by differences in morphology, migration behavior, and annual cycle phenology, in a global distribution thought to have arisen just since the last glacial maximum (LGM). We used nextRAD sequencing of 10,881 single‐nucleotide polymorphisms (SNPs) to assess the neutral genetic structure and phylogeographic history of 172 red knots representing all known global breeding populations. Using population genetics approaches, including model‐based scenario‐testing in an approximate Bayesian computation (ABC) framework, we infer that red knots derive from two main lineages that diverged ca. 34,000 years ago, and thus most probably persisted at the LGM in both Palearctic and Nearctic refugia, followed by at least two instances of secondary contact and admixture. Within two Beringian subspecies (C. c. roselaari and rogersi), we detected previously unknown genetic structure among sub‐populations sharing a migratory flyway, reflecting additional complexity in the phylogeographic history of the region. Conversely, we found very weak genetic differentiation between two Nearctic populations (rufa and islandica) with clearly divergent migratory phenotypes and little or no apparent contact throughout the annual cycle. Together, these results suggest that relative gene flow among migratory populations reflects a complex interplay of historical, geographical, and ecological factors.
In long-lived marine predators such as penguins, foraging behaviour is related to breeding success. Yellow-eyed penguins Megadyptes antipodes are thought to be predominantly benthic foragers around ...mainland New Zealand, with previous dive studies showing little variation in diving behaviour and minimal change by year or breeding status. This apparent absence of foraging flexibility may be linked to local prey availability and therefore also to foraging success, factors believed to contribute to the current population decline. Here, we undertook the first detailed study of yellow-eyed penguin diving and foraging behaviour in the subantarctic Auckland Islands, part of the original ancestral range of the species that colonised mainland New Zealand. We collected dive logs from 134 foraging trips made by 73 breeders from Enderby Island, Auckland Islands, in the New Zealand subantarctic. Pelagic dives and foraging trips were recorded in the subantarctic population—a foraging strategy not previously published in dive studies on this species. Changes between benthic and pelagic foraging were recorded for individuals within foraging trips, within a breeding season, and between years. Differences in diving behaviour between the subantarctic and that reported for mainland New Zealand are likely influenced by local bathymetry and environmental conditions, and prey availability. However, the subantarctic population shows a greater use of pelagic foraging not evident in the northern population, even in areas that have a similar depth to some mainland foraging areas. This observed foraging flexibility may have implications for breeding success and potentially the long-term population trends of these 2 genetically similar populations.
Despite clear benefits of optimal arrival time on breeding grounds, migration schedules may vary with an individual bird's innate quality, non-breeding habitat or breeding destination. Here, we show ...that for the bar-tailed godwit (Limosa lapponica baueri), a shorebird that makes the longest known non-stop migratory flights of any bird, timing of migration for individual birds from a non-breeding site in New Zealand was strongly correlated with their specific breeding latitudes in Alaska, USA, a 16,000-18,000 km journey away. Furthermore, this variation carried over even to the southbound return migration, 6 months later, with birds returning to New Zealand in approximately the same order in which they departed. These tightly scheduled movements on a global scale suggest endogenously controlled routines, with breeding site as the primary driver of temporal variation throughout the annual cycle.
The pace and scale of environmental change represent major challenges to many organisms. Animals that move long distances, such as migratory birds, are especially vulnerable to change since they need ...chains of intact habitat along their migratory routes. Estimating the resilience of such species to environmental changes assists in targeting conservation efforts. We developed a migration modeling framework to predict past (1960s), present (2010s), and future (2060s) optimal migration strategies across five shorebird species (Scolopacidae) within the East Asian-Australasian Flyway, which has seen major habitat deterioration and loss over the last century, and compared these predictions to empirical tracks from the present. Our model captured the migration strategies of the five species and identified the changes in migrations needed to respond to habitat deterioration and climate change. Notably, the larger species, with single or few major stopover sites, need to establish new migration routes and strategies, while smaller species can buffer habitat loss by redistributing their stopover areas to novel or less-used sites. Comparing model predictions with empirical tracks also indicates that larger species with the stronger need for adaptations continue to migrate closer to the optimal routes of the past, before habitat deterioration accelerated. Our study not only quantifies the vulnerability of species in the face of global change but also explicitly reveals the extent of adaptations required to sustain their migrations. This modeling framework provides a tool for conservation planning that can accommodate the future needs of migratory species.
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