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Understanding which factors cause populations to decline begins with identifying which parts of the life cycle, and which vital rates, have changed over time. However, in a world where humans are altering the environment both rapidly and in different ways, the demographic causes of decline likely vary over time. Identifying temporal variation in demographic causes of decline is crucial to assure that conservation actions target current and not past threats. However, this has rarely been studied as it requires long time series. Here we investigate how the demography of a long-lived shorebird (the Eurasian Oystercatcher Haematopus ostralegus) has changed in the past four decades, resulting in a shift from stable dynamics to strong declines (−9% per year), and recently back to a modest decline. Since individuals of this species are likely to respond differently to environmental change, we captured individual heterogeneity through three state variables: age, breeding status, and lay date (using integral projection models). Timing of egg-laying explained significant levels of variation in reproduction, with a parabolic relationship of maximal productivity near the average lay date. Reproduction explained most variation in population growth rates, largely due to poor nest success and hatchling survival. However, the demographic causes of decline have also been in flux over the last three decades: hatchling survival was low in the 2000s but improved in the 2010s, while adult survival declined in the 2000s and remains low today. Overall, the joint action of several key demographic variables explain the decline of the oystercatcher, and improvements in a single vital rate cannot halt the decline. Conservations actions will thus need to address threats occurring at different stages of the oystercatcher’s life cycle. The dynamic nature of the threat landscape is further supported by the finding that the average individual no longer has the highest performance in the population, and emphasizes how individual heterogeneity in vital rates can play an important role in modulating population growth rates. Our results indicatethat understanding population decline in the current era requires disentangling demographic mechanisms, individual variability, and their changes over time.

Changes in the frequency of extreme climatic events (ECEs) can have profound impacts on individual fitness by degrading habitat quality. Organisms may respond to such changes through habitat selection, favouring those areas less affected by ECEs; however, documenting habitat selection in response to ECEs is difficult in the wild due to the rarity of such events and the long‐term biological data required. Sea level rise and changing weather patterns over the past decades have led to an increase in the frequency of coastal flooding events, with serious consequences for ground nesting shorebirds. Shorebirds therefore present a useful natural study system to understand habitat selection as a response to ECEs. We used a 32‐year study of the Eurasian oystercatcher (Haematopus ostralegus) to investigate whether habitat selection can lead to an increase in nest elevation and minimize the impacts of coastal flooding. The mean nest elevation of H. ostralegus has increased during the last three decades. We hypothesized that this change has been driven by changes in H. ostralegus territory settlement patterns over time. We compared various possible habitat selection cues to understand what information H. ostralegus might use to inform territory settlement. There was a clear relationship between elevation and territory settlement in H. ostralegus. In early years, settlements were more likely at low elevations but in more recent years the likelihood of settlement was similar between high and low elevation areas. Territory settlement was associated with conspecific fledgling output and conspecific density. Settlement was more likely in areas of high density and areas with high fledgling output. This study shows that habitat selection can minimize the effects of increasingly frequent ECEs. However, it seems unlikely that the changes we observe will fully alleviate the consequences of anthropogenic climate change. Rates of nest elevation increase were insufficient to track current increases in maximum high tide (0.5 vs. 0.8 cm/year). Furthermore, habitat selection cues that rely on information from previous breeding seasons (e.g. conspecific fledgling output) may become ineffective as ECEs become more frequent and environmental predictability is diminished. The authors use 30 years of coastal shorebird breeding data to demonstrate how habitat selection can reduce the effects of more frequent extreme climatic events. Changes in the territory settlement behaviour of birds have led to an increase in nest elevation. Higher elevation nest sites are less affected by flooding events.

Environment and behavior are widely understood to affect bird morphology, which can lead to differences among subspecies or populations within a wide‐ranging species. Several patterns of latitudinal gradients in morphology have been described, though Allen's and Bergmann's rules are the most well‐known and have been tested and confirmed across a diversity of taxa and species. These state that individuals at higher latitudes will have larger bodies (Bergmann's Rule) but smaller extremities (Allen's Rule) to conserve heat in colder climates. Migratory behavior also can influence avian morphology, particularly wing shape, where migratory birds tend to have longer, more pointed wings than residents. The Black Oystercatcher (Haematopus bachmani) is a large, partially migratory shorebird species restricted to intertidal habitats and distributed from Alaska to Baja California, spanning about 35° of latitude. A large proportion of Black Oystercatchers that breed in Alaska are migratory, where nearly all individuals breeding in British Columbia through the southern end of their range remain resident through the annual cycle. Their broad latitudinal range and diversity in migratory behavior may drive geographic variation in morphology. Here we evaluate three explanations for geographic variation in morphology of the Black Oystercatcher using data from seven sites across two regions: Alaska and British Columbia. We found evidence consistent with Allen's but not Bergmann's rule; birds in Alaska have shorter bills than those in British Columbia, and these findings held when controlling for body size using wing length. Despite regional differences in migratory behavior, we detected no difference in the wing shape of birds in Alaska and British Columbia. Differences between sexes and among sites suggest that multiple factors drive patterns of morphological variation in the Black Oystercatcher. This study tests whether populations of Black Oystercatchers (Haematopus bachmani) across Alaska, the United States, and British Columbia, Canada, follow patterns of latitudinal gradients in morphology. Specifically, we test for patterns of Allen's and Bergmann's Rules, as well as differences in wing morphology based on migratory strategy. This study provides support for Allen's Rule in the Black Oystercatcher; those in northern latitudes have shorter bills, though it does not find evidence of Bergmann's Rule or the influence of migratory strategy on wing shape in this species.

Black Oystercatcher (Haematopus bachmani) is an important indicator species for the ecological integrity of rocky coastal ecosystems of western North America. From 2007 to 2022, 49 Black Oystercatchers were banded and resighted in subsequent years in and around Pacific Rim National Park Reserve on Vancouver Island, British Columbia, Canada. We used Cormack-Jolly-Seber mark–recapture models on 16 years of encounter histories to estimate apparent adult annual survival (u), encounter probability (p), and to determine if there was a sex effect on apparent survival. The apparent survival estimate was high (0.91 6 0.02), as reported for other oystercatcher species. Apparent survival was not sex-dependent, but encounter probability was 9.8% higher in females (0.96 6 0.02) than in males (0.87 6 0.03), for reasons we cannot definitively establish. The population trend in the studied population for 2008–2022 was estimated at 3.47 6 0.50%, indicating a growing population with an apparent surplus of adult individuals. These survival, encounter, and population trend estimates are important for future monitoring of the Pacific Rim and other Black Oystercatcher populations. El ostrero Haematopus bachmani es una especie importante indicadora de la integridad ecológica del ecosistemas costeros rocosos en el oeste de Norteamérica. Del 2007 al 2022, 49 ostreros Haematopus bachmani fueron anillados y reobservados en años siguientes dentro y alrededor de Pacific Rim National Park Reserve en Vancouver Island, British Columbia, Canadá. Usamos modelos de marca-recaptura de Cormack-Jolly-Seber para 16 años de historial de encuentros para estimar el efecto de la sobrevivencia aparente (u), probabilidad de encuentros (p) y determinar si había un efecto de sexo en la sobrevivencia aparente. La tasa de sobrevivencia aparente fue alta (0.916 0.02), como ha sido reportado para otras especies de ostreros. La sobrevivencia aparente no dependía del sexo, pero la probabilidad de encuentro era 9.8% mayor en hembras (0.96 6 0.02) que en machos (0.87 6 0.03), por razones que no podemos establecer de forma definitiva. La tendencia poblacional en la población estudiada para 2008–2022 fue estimada en 3.47 6 0.50%, lo que indica una población creciente con un aparente excedente de individuos adultos. Estas estimaciones de sobrevivencia, encuentro y tendencias poblacionales son importantes para futuros monitoreos de la población de ostreros de Pacific Rim y de otras poblaciones. Palabras clave: intermareal, marca-recaptura, modelo Cormack-Jolly-Seber, TRIM, zona costera.

Climate change affects both the mean and variability of climatic variables, but their relative impact on the dynamics of populations is still largely unexplored. Based on a long-term study of the demography of a declining Eurasian Oystercatcher ( Haematopus ostralegus ) population, we quantify the effect of changes in mean and variance of winter temperature on different vital rates across the life cycle. Subsequently, we quantify, using stochastic stage-structured models, how changes in the mean and variance of this environmental variable affect important characteristics of the future population dynamics, such as the time to extinction. Local mean winter temperature is predicted to strongly increase, and we show that this is likely to increase the population's persistence time via its positive effects on adult survival that outweigh the negative effects that higher temperatures have on fecundity. Interannual variation in winter temperature is predicted to decrease, which is also likely to increase persistence time via its positive effects on adult survival that outweigh the negative effects that lower temperature variability has on fecundity. Overall, a 0.1°C change in mean temperature is predicted to alter median time to extinction by 1.5 times as many years as would a 0.1°C change in the standard deviation in temperature, suggesting that the dynamics of oystercatchers are more sensitive to changes in the mean than in the interannual variability of this climatic variable. Moreover, as climate models predict larger changes in the mean than in the standard deviation of local winter temperature, the effects of future climatic variability on this population's time to extinction are expected to be overwhelmed by the effects of changes in climatic means. We discuss the mechanisms by which climatic variability can either increase or decrease population viability and how this might depend both on species' life histories and on the vital rates affected. This study illustrates that, for making reliable inferences about population consequences in species in which life history changes with age or stage, it is crucial to investigate the impact of climate change on vital rates across the entire life cycle. Disturbingly, such data are unavailable for most species of conservation concern.

Migratory connectivity describes linkages between breeding and non-breeding areas. An ongoing challenge is tracking avian species between breeding and non-breeding areas and hence estimating migratory connectivity and seasonal survival. Collaborative color-ringing projects between researchers and citizen scientists provide opportunities for tracking the annual movements of avian species. Our study describes seasonal survival and migratory connectivity using data from more than 4,600 individuals with over 51,000 observations, predominantly collected by citizen scientists. Our study focuses on the Eurasian Oystercatcher (Haematopus ostralegus), a species that has experienced a substantial and ongoing decline in recent decades. Multiple threats have been described, and given that these threats vary in space and time, there is an urgent need to estimate demographic rates at the appropriate spatio-temporal scale. We performed a seasonal multi-state (5 geographical areas within The Netherlands) live- and dead-recoveries analysis under varying model structures to account for biological and data complexity. Coastal breeding populations were largely sedentary, while inland breeding populations were migratory and the direction of migration varied among areas, which has not been described previously. Our results indicated that survival was lower during winter than summer and that survival was lower in inland areas compared with coastal areas. A concerning result was that seasonal survival of individuals over-wintering in the Wadden Sea, an internationally important site for over-wintering shorebirds, appeared to decline during the study period. We discuss the outcomes of our study, and how citizen science was integral for conducting this study. Our findings identify how the demographic rates of the oystercatcher vary in space and time, knowledge that is vital for generating hypotheses and prioritizing future research into the causes of decline.

Habitat characteristics and microhabitat of organisms pose a number of choices to foraging species, for example where and how to search for prey, which prey to select and what foraging technique to employ. Predators can enhance the profitability of foraging by adapting their strategies flexibly in relation to prey characteristics and environmental factors. To investigate the influence of rocky shore characteristics viz., condition of rock, position of limpet on the rock, stage of tide, and limpet opening technique of oystercatcher on the profitability of limpet foraging, a total of 193 attacks on limpets ( Patella spp.) by Eurasian oystercatchers ( Haematopus ostralegus ) were made on Lundy Island, UK, using focal animal sampling. Multiple regression revealed that profitability was influenced by the condition of the rock and the limpet opening technique employed by oystercatchers. The profitability of the limpet opening technique appears to be associated with the condition of the rock. Oystercatchers forage by adapting their foraging strategy in accordance with the nature of the rocks i.e. wetness on which they are foraging.

In many emerging nations, rapid industrialization and urbanization have led to heightened levels of air pollution. This sudden rise in air pollution, which affects global sustainability and human health, has become a significant concern for citizens and governments. While most current methods for predicting air quality rely on shallow models and often yield unsatisfactory results, our study explores a deep architectural model for forecasting air quality. We employ a sophisticated deep learning structure to develop an advanced system for ambient air quality prediction. We utilize three publicly available databases and real-world data to obtain accurate air quality measurements. These four datasets undergo a data cleaning to yield a consolidated, cleaned dataset. Subsequently, the Fused Eurasian Oystercatcher-Pathfinder Algorithm (FEO-PFA)—a dual optimization method combining the Eurasian Oystercatcher Optimizer (EOO) and Pathfinder Algorithm (PFA)—is applied. This method aids in selecting weighted features, optimizing weights, and choosing the most relevant attributes for optimal results. These optimal features are then incorporated into the Multiscale Depth-wise Separable Adaptive Temporal Convolutional Network (MDS-ATCN) for the ambient Air Quality Prediction (AQP) process. The variables within MDS-ATCN are further refined using the proposed FEO-PFA to enhance predictive accuracy. An empirical analysis is performed to compare the efficacy of our proposed model with traditional methods, underscoring the superior effectiveness of our approach. The average cost function is reduced to 5.5%, the MAE to 28%, and the RMSE to 14% by the suggested method, according to the performance research conducted with regard to all datasets.

I explored the fitness implications of individual and sex differences in foraging strategy in the Eurasian oystercatcher Haematopus ostralegus by monitoring the survival of individually colour-ringed birds of known sex and known feeding specialisation. Over the period of this study, adult female annual and overwinter survival was significantly lower than adult male survival. However, contrary to previous findings, no differences in survival were found between birds of different feeding specialisations. Lower female survival was not due to sex differences in feeding specialisation. Possible mechanisms for sex differences in survival and the survival implications of different feeding specialisations are discussed. I conclude that sex differences in survival may be due to differences in social status. I also suggest that worm/clam feeders and mussel-stabbers, feeding specialisations previously associated with lower survival rates, may have benefited more than mussel-hammerers from milder winter temperatures in recent years.

Aim: Resource-selection functions (RSFs) can quantify and predict the density of animal populations across heterogeneous landscapes and are important conservation tools in areas subject to human disturbance. Sandy beach ecosystems have comparatively low habitat heterogeneity and structural relief in the intertidal zone, but intense human use. We aimed to develop predictive RSFs for birds on ocean-exposed sandy beaches at two spatial scales, 25 ha (local scale) and 250 ha (landscape scale), and to test whether habitat selection of birds that commonly use the surf-beach-dune interface is influenced by the rates of human activities. Location: Moreton and North Stradbroke Island, eastern Australia. Methods: Avifauna and human activities were mapped on three sandy beaches covering 79 km of coastline for 15 months. Habitat characteristics of the surfbeach-dune interface were derived from remote sensing and ground surveys. RSFs were developed for 12 species of birds at two spatial scales: 25 ha (local scale) and 250 ha (landscape scale). Results: At local (25 ha) and landscape scales (250 ha), dune dimensions and the extent and type of vegetation structure were important predictors of bird density. Adding the frequency of human activities improved the predictive power of RSFs, suggesting that habitat selection of birds on beaches is modified by human use of these environments. Human activities occurred mostly in the mid-to lower intertidal zone of the beach, overlapping closely with the preferred habitats of Silver Gulls (Larus novaehollandiae), Pied Oystercatchers (Haematopus longirostris), Red-capped Plovers (Charadrius ruficapillus) and endangered Little Terns (Sternuta albifrons). Main conclusions: In addition to demonstrating the appropriateness of RSFs to the surf-beach-dune interface, our results stress the need for systematic conservation planning for these ecosystems, where ecological values have traditionally been subsidiary to the maintenance of sand budgets and erosion control.