Short-distance Migrants Research Articles

Unravelling intermediate migration patterns in gull hybrids: insights from ring re-encounters

Hybridization is a common phenomenon in birds, particularly between closely related species, when reproductive isolation mechanisms are insufficiently developed. Hybrids differ from the parental species in genetic, morphological, and behavioural traits. However, the migration patterns of hybrids have been scarcely studied. Examining hybrid migration behaviour is essential as it may reveal their role as a “gene bridge” between species and enhance our understanding of speciation mechanisms and the genetics of migration. Most research focuses on tracking the migration of long-distance migrants, but the effect of hybridization on migration is poorly understood also in short-distance migrants. The study aimed to verify whether the migratory movements of interspecific hybrids between the Herring (Larus argentatus) and the Caspian Gull (L. cachinnans) are intermediate, as predicted by the genetic basis of migration. Migration patterns, based on distance and direction, were determined from re-encounter data of individuals ringed in Poland, for over 20 years (2002–2023). These included both allopatric (parental species) and sympatric (both parental species and hybrids) populations. The results indicated that large gull hybrids exhibit an intermediate migration patterns, similarly to other hybridizing species. Unlike many cases where intermediacy may select against hybrids, the absence of significant environmental barriers along gulls’ migration routes and their wide wintering range likely mitigates selective pressures. This finding underscores the need for further investigation into the ecological implications of hybrid migration patterns. By using bird re-encounter data, we demonstrated that it provides a sufficient basis for analysing migration patterns and detecting intermediacy, even in within-continental and short-distance migrants.

Avian diversity across guilds in North America versus vegetation structure as measured by the Global Ecosystem Dynamics Investigation (GEDI)

Avian diversity, a key indicator of ecosystem health, is closely related to canopy structure. Most avian diversity models are based on either optical remote sensing or airborne lidar data, but the latter is limited to small study areas. The launch of the Global Ecosystem Dynamics Investigation (GEDI) instrument in 2018 has opened new avenues for exploring the influence of vegetation structure on avian diversity. To examine how direct measurements of canopy structural characteristics explain bird diversity across North America, we analyzed 18 GEDI metrics from 2019 to 2022, along with corresponding Breeding Bird Survey (BBS) counts and AVONET morphological data, analyzing effects across broad regions and at varying spatial extents. We grouped 440 bird species into 20 ecological guilds under six guild categories and employed random forest algorithms to model avian diversity across eight spatial extents (1, 2, 3, 4, 5, 10, 20, and 39.2 km). The models predicted six diversity indices, including species richness (sRich), functional richness (fRich), evenness (fEve), dispersion (fDis), divergence (fDiv), and redundancy (fRed) across eight spatial extents. The best-predicted guilds varied for each diversity index. The most accurate models were sRich (pseudo-R2 = 0.71, RMSE = 4.28) and fRed (pseudo-R2 = 0.60, RMSE = 0.13) for forest specialists guilds; fRich (pseudo-R2 = 0.55, RMSE = 0.18) for urban guilds; fEve (pseudo-R2 = 0.28, RMSE = 0.08) for insectivore guilds; and fDiv (pseudo-R2 = 0.38, RMSE = 0.12) and fDis (pseudo-R2 = 0.53, RMSE = 0.87) for short distance migrants guilds. Our results highlight the critical role of canopy structure, including its horizontal and vertical distribution and variation, in predicting avian diversity, as measured by the mean number of detected modes (num_detectedmodes), the standard deviation of foliage height diversity (FHD), num_detectedmodes, canopy cover, and plant area index (PAI) across the spatial extents centered on BBS routes. Therefore, we recommend incorporating the GEDI metrics into avian diversity modeling and mapping across North America, thereby potentially enhancing bird habitat management and conservation efforts.

Migratory behaviour of Ipswich Sparrows during spring

Optimal migration theory predicts birds will follow migration strategies that minimize time, energy, or predation risk, and these strategies employ specific and conflicting behaviours. Many behaviours driving songbird strategies are relatively well known, however gaps remain, especially for spring migration. Here, we describe the behaviours of a short-distance migrant, the Ipswich Sparrow ( Passerculus sandwichensis princeps Maynard, 1872), during spring migration. We determined the start and end dates of migration, migratory duration, travel speed, distance per night, and stopover location and duration. We also examined whether behaviours differed by sex and age. Sparrows migrated between March and June, and took an average of 29.1 days at a speed of 7.2 ± 9.4 m/s (SD) to fly ∼1574 km to their breeding grounds. Sparrows flew approximately 100 km/night and made stopovers of >7 days adjacent to ecological barriers. Males migrated before females, and behaviour did not differ with age. Overall, Ipswich Sparrows had a relatively slow travel speed and covered short distances each night consistent with efforts to minimize energy costs or predation risk. They had prolonged stopovers suggesting that they were also trying to minimize time. More work is required to determine which strategy sparrows may be using during spring migration.

Among-species variation in six decades of changing migration timings explained through ecology, life-history and local migratory abundance.

Species exploiting seasonal environments must alter timings of key life-history events in response to large-scale climatic changes in order to maintain trophic synchrony with required resources. Yet, substantial among-species variation in long-term phenological changes has been observed. Advancing from simply describing such variation towards predicting future phenological responses requires studies that rigorously quantify and explain variation in the direction and magnitude of changing timings across diverse species in relation to key ecological and life-history variables. Accordingly, we fitted multi-quantile regressions to 59 years of multi-species data on spring and autumn bird migration timings through northern Scotland. We demonstrate substantial variation in changes in timings among 72 species, and tested whether such variation can be explained by species ecology, life-history and changes in local abundance. Consistent with predictions, species that advanced their migration timing in one or both seasons had more seasonally restricted diet types, fewer suitable breeding habitat types, shorter generation lengths and capability to produce multiple offspring broods per year. In contrast, species with less seasonally restricted diet types and that produce single annual offspring broods, showed no change. Meanwhile, contrary to prediction, long-distance and short-distance migrants advanced migration timings similarly. Changes in migration timing also varied with changes in local migratory abundance, such that species with increasing seasonal abundance apparently altered their migration timing, whilst species with decreasing abundance did not. Such patterns broadly concur with expectation given adaptive changes in migration timing. However, we demonstrate that similar patterns can be generated by numerical sampling given changing local abundances. Any apparent phenology-abundance relationships should, therefore, be carefully validated and interpreted. Overall, our results show that migrant bird species with differing ecologies and life-histories showed systematically differing phenological changes over six decades contextualised by large-scale environmental changes, potentially facilitating future predictions and altering temporal dynamics of seasonal species co-occurrences.

The role of a non-native forest in the stopover ecology of migratory passerines

During their journey, migratory birds need stopover sites where they can replenish their energy stores. Mosaic forests of agricultural areas, often planted with non-native trees, can provide opportunities for birds to do this. In the present work, I sought to answer the question of the importance of these habitats for migratory birds. For this reason I studied the stopover ecology of 15 species of long- and short-distance migratory passerines. I calculated the minimum stopover duration and the extent of fat accumulation per species and by dividing species into different groups by habitat use and migration distance. For three species, I also estimated their possible flight ranges based on the accumulated fat, body mass and wing length. My results show that the planted oleaster forest has a different role in the stopover habits of the species studied. The body mass of the birds typically did not changed significantly during the time they spent in the area. Forest and farmland species spent the longest time in the area. Despite the possibly high rate of intra- and inter-specific competition, the area can provide sufficient food for birds throughout the whole period. Short-distance migrants stored less fat than long-distance migrants, probably due to the different migration strategies. Flight distances varied according to the migratory habits of the species. From a conservation biology point of view, the study highlighted the role of these habitats in bird migration.

Bird population changes in urban green spaces explained by regional population trends

Urban bird species represent a subset of the regional species pool, consisting of species that have been able to survive in, or colonise, urban areas. Urban birds are typically resident non-forest species with a broad diet and nesting high in trees or in cavities, and some studies have also claimed that they are large-brained. However, little is known about how urban bird communities change over time. Does the urban environment impose specific selective pressures favouring particular species or ecological groups, or do birds in urban areas simply have population changes reflecting population trends at larger scales? We assessed population changes of 45 breeding land bird species in Oslo, the capital of Norway, based on surveys conducted ca. 15 years apart. Population changes within Oslo most closely matched changes occurring at the regional level (national population trends from Norway and Sweden). Thus, species increasing in Oslo were those that also increased at the regional level. We found no evidence that relative brain size, diet or habitat preferences influenced population trends. However, controlling for regional population trends, there were additional residual effects of nest site and migration: species nesting on the ground or low in bushes had more positive changes than species nesting high in trees or in cavities, and resident species did better than long- or short-distance migrants. These results indicate that urban environments are not isolated islands only influenced by own selection pressures, but are connected with regional population dynamics, most likely through immigration.

The effects of diet-shifting from invertebrates towards fruit on the condition of autumn-migrant Catharus thrushes.

Migration is an energetically challenging and risky life history stage for many animals, but could be supported by dietary choices en route, which may create opportunities to improve body and physiological condition. However, proposed benefits of diet shifts, such as between seasonally available invertebrates and fruits, have received limited investigation in free-living animals. We quantified diet composition and magnitude of autumn diet shifts over two time periods in two closely-related species of migratory songbirds on stopover in the northeastern U.S. (Swainson's thrush [Catharus ustulatus], long-distance migrant, N = 83; hermit thrush [C. guttatus], short-distance migrant, N = 79) and used piecewise structural equation models to evaluate the relationships among (1) migration timing, (2) dietary behavior, and (3) morphometric and physiological condition indices. Tissue isotope composition indicated that both species shifted towards greater fruit consumption. Larger shifts in recent weeks corresponded to higher body condition in Swainson's, but not hermit thrushes, and condition was more heavily influenced by capture date in Swainson's thrushes. Presence of "high-antioxidant" fruits in fecal samples was unrelated to condition in Swainson's thrushes and negatively related to multiple condition indices in hermit thrushes, possibly indicating the value of fruits during migration is related more to their energy and/or macronutrient content than antioxidant content. Our results suggest that increased frugivory during autumn migration can support condition, but those benefits might depend on migration strategy: a longer-distance, more capital-dependent migration strategy could require stricter regulation of body condition aided by increased fruit consumption.

Consistent delay in recent timing of passerine autumn migration

Climate change affects important biological processes, bird migration phenology being a particular well-documented one. While spring migration have been found to advance by numerous studies, autumn migration is less studied and show more variable change in timing. Few studies of autumn migration are based on data from after 2000, leaving the last two decades to be relatively less studied. Here, we investigate recent change in autumn migration phenology of European passerines. The most recent available bird ringing data from Denmark is used to analyse phenological change of median and late migration of 14 passerine migrants between 2003–2021. We find an overall delay of autumn migration, mainly driven by short-distance migrants. All short-distance migrants, one out of five medium-distance and three out of five long-distance migrants delay autumn migration. None of the included species advance autumn migration significantly. As climate change has continuously resulted in milder conditions in north-western Europe, we expect this to cause further effects on migration phenology also in recent decades. Our results provide novel insight into recent migration phenology trends, and the observed delay in long-distance migrants may illustrate a changed response to climate change.

Population trend and breeding productivity of some migrant passerines in Hungary

Abstract This study aimed to monitor the demographic changes of some closely related species based on bird ringing data from the CES (Constant Effort Sites) program in Hungary between 2007 and 2018, and to explore the reasons for these demographic changes. The CES program tracks breeding bird populations with standard methods. The studied species breeding in Hungary were from genera Sylvia, Curruca, and Phylloscopus. Among these species, the trends of some forest birds, like Eurasian Blackcap (Sylvia atricapilla), Lesser Whitethroat (Curruca curruca), Common Chiffchaff (Phylloscopus collybita) and Willow Warbler (Ph. trochilus) showed no substantial changes, and one of the open-habitat species, the Barred Warbler (Curruca nisoria) – a long distant migrant – showed decreasing trends. The Garden Warbler (Sylvia borin) – a trans-Saharan migrant but forest dweller – also experienced population declines. Short-distance migrants maintained stable populations. Common Whitethroat productivity displayed an increasing trend to compensate for population decline. Upon examining the Eurasian Blackcap, this study detected a strong relationship between the number of adult birds, productivity, and the number of adults captured the following year.

Got milkweed? Genetic assimilation as potential source for the evolution of nonmigratory monarch butterfly wing shape.

Monarch butterflies (Danaus plexippus) are well studied for their annual long-distance migration from as far north as Canada to their overwintering grounds in Central Mexico. At the end of the cold season, monarchs start to repopulate North America through short-distance migration over the course of multiple generations. Interestingly, some populations in various tropical and subtropical islands do not migrate and exhibit heritable differences in wing shape and size, most likely an adaptation to island life. Less is known about forewing differences between long- and short-distance migrants in relation to island populations. Given their different migratory behaviors, we hypothesized that these differences would be reflected in wing morphology. To test this, we analyzed forewing shape and size of three different groups: nonmigratory, lesser migratory (migrate short-distances), and migratory (migrate long-distances) individuals. Significant differences in shape appear in all groups using geometric morphometrics. As variation found between migratory and lesser migrants has been shown to be caused by phenotypic plasticity, and lesser migrants develop intermediate forewing shapes between migratory and nonmigratory individuals, we suggest that genetic assimilation might be an important mechanism to explain the heritable variation found between migratory and nonmigratory populations. Additionally, our research confirms previous studies which show that forewing size is significantly smaller in nonmigratory populations when compared to both migratory phenotypes. Finally, we found sexual dimorphism in forewing shape in all three groups, but for size in nonmigratory populations only. This might have been caused by reduced constraints on forewing size in nonmigratory populations.

The pace of mitochondrial molecular evolution varies with seasonal migration distance.

Animals that engage in long-distance seasonal migration experience strong selective pressures on their metabolic performance and life history, with potential consequences for molecular evolution. Species with slow life histories typically show lower rates of synonymous substitution (dS) than "fast" species. Previous research suggests long-distance seasonal migrants have a slower life history strategy than short-distance migrants, raising the possibility that rates of molecular evolution may covary with migration distance. Additionally, long-distance migrants may face strong selection on metabolically-important mitochondrial genes due to their long-distance flights. Using over 1,000 mitochondrial genomes, we assessed the relationship between migration distance and mitochondrial molecular evolution in 39 boreal-breeding migratory bird species. We show that migration distance correlates negatively with dS, suggesting that the slow life history associated with long-distance migration is reflected in rates of molecular evolution. Mitochondrial genes in every study species exhibited evidence of purifying selection, but the strength of selection was greater in short-distance migrants, contrary to our predictions. This result may indicate effects of selection for cold tolerance on mitochondrial evolution among species overwintering at high latitudes. Our study demonstrates that the pervasive correlation between life history and molecular evolutionary rates exists in the context of differential adaptations to seasonality.

Clear-cuts and warming summers caused forest bird populations to decline in a southern boreal area

Land use and climate change are the main drivers of biodiversity change. However, their relative roles in the decline of biodiversity are still insufficiently known. Climate change is expected to be globally most pronounced in the boreal biome, where another key driver affecting boreal species is forestry. In NW Europe almost all forest land outside protected areas is subject to systematic forest management practices including clear-cutting, thinning and replanting. In addition, a human-caused increase in herbivores, such as ungulates, may affect the forest vegetation structure and thereby also bird species. We studied population changes of a bird community in a southern boreal area in Finland over a period of 30 years and related changes in the bird community concerning both land use and climate variables. During the study the total bird density declined by 26%, i.e., 1%/year. Long-distance migrants and residents declined the most, both by 44%, and short-distance migrants by 29%, while partial migrants increased by 29%. Clear-cuts were the most important variable explaining the decline in the total bird density and the density change of long-distance and short-distance migrants and residents. In addition, the higher summer mean temperature was related to the decline of the total bird density and short-distance migrants, which were also moderately negatively affected by the ungulate density. The increase in partial migrants was mostly due to an increase in the numbers of two bird species, the great tit Parus major and the blue tit Cyanistes caeruleus, which have benefitted from human actions in many ways. As a whole, the bird community did not recover to the level that prevailed before the clear-cuts in the study period. This indicates that recolonisation and the recovery rate by birds in maturing young stands cannot fully compensate for the loss of birds resulting from the clear-cuts. Forest management practices should adopt more biodiversity-friendly methods, such as continuous cover forestry, to better maintain populations of forest birds.

Fitness, behavioral, and energetic trade-offs of different migratory strategies in a partially migratory species.

Alternative migratory strategies can coexist within animal populations and species. Anthropogenic impacts can shift the fitness balance between these strategies leading to changes in migratory behaviors. Yet some of the mechanisms that drive such changes remain poorly understood. Here we investigate the phenotypic differences, and the energetic, behavioral, and fitness trade-offs associated with four different movement strategies (long-distance and short-distance migration, and regional and local residency) in a population of white storks (Ciconia ciconia) that has shifted its migratory behavior over the last decades, from fully long-distance migration toward year-round residency. To do this, we tracked 75 adult storks fitted with GPS/GSM loggers with tri-axial acceleration sensors over 5 years, and estimated individual displacement, behavior, and overall dynamic body acceleration, a proxy for activity-related energy expenditure. Additionally, we monitored nesting colonies to assess individual survival and breeding success. We found that long-distance migrants traveled thousands of kilometers more throughout the year, spent more energy, and >10% less time resting compared with short-distance migrants and residents. Long-distance migrants also spent on average more energy per unit of time while foraging, and less energy per unit of time while soaring. Migratory individuals also occupied their nests later than resident ones, later occupation led to later laying dates and a lower number of fledglings. However, we did not find significant differences in survival probability. Finally, we found phenotypic differences in the migratory probability, as smaller sized individuals were more likely to migrate, and they might be incurring higher energetic and fitness costs than larger ones. Our results shed light on the shifting migratory strategies in a partially migratory population and highlight the nuances of anthropogenic impacts on species behavior, fitness, and evolutionary dynamics.

Co-migration fidelity at a stopover site increases over time in African-European migratory landbirds.

Migratory species are changing their timing of departure from wintering areas and arrival to breeding sites (i.e. migration phenology) in response to climate change to exploit maximum food availability at higher latitudes and improve their fitness. Despite the impact of changing migration phenology at population and community level, the extent to which individual and species-specific response affects associations among co-migrating species has been seldom explored. By applying temporal co-occurrence network models on 15 years of standardized bird ringing data at a spring stopover site, we show that African-European migratory landbirds tend to migrate in well-defined groups of species with high temporal overlap. Such 'co-migration fidelity' significantly increased over the years and was higher in long-distance (trans-Saharan) than in short-distance (North African) migrants. Our findings suggest non-random patterns of associations in co-migrating species, possibly related to the existence of regulatory mechanisms associated with changing climate conditions and different uses of stopover sites, ultimately influencing the global economy of migration of landbirds in the Palearctic-African migration system.

Bird species with wider geographical ranges have higher blood parasite diversity but not prevalence across the African-Eurasian flyway

Avian blood parasites, from the genera Plasmodium, Haemoproteus and Leucocytozoon, are predicted to alter their range and prevalence as global temperatures change, and host and vector ranges shift. Understanding large-scale patterns in the prevalence and diversity of avian malaria and malaria-like parasites is important due to an incomplete understanding of their effects in the wild, where studies suggest even light parasitaemia can potentially cause rapid mortality, especially in naïve populations. We conducted phylogenetically controlled analyses to test for differences in prevalence and lineage diversity of haemoparasite infection (for Plasmodium, Haemoproteus and Leucocytozoon) in and between resident and migratory species along the African-Eurasian flyway. To test whether migratory strategy or range size drives differences in parasite prevalence and diversity between resident and migrant species, we included three categories of resident species: Eurasian only (n = 36 species), African only (n = 41), and species resident on both continents (n = 17), alongside intercontinental migrants (n = 64), using a subset of data from the MalAvi database comprising 27,861 individual birds. We found that species resident on both continents had a higher overall parasite diversity than all other categories. Eurasian residents had lower Plasmodium diversity than all other groups, and both migrants and species resident on both continents had higher Haemoproteus diversity than both African and Eurasian residents. Leucocytozoon diversity did not differ between groups. Prevalence patterns were less clear, with marked differences between genera. Both Plasmodium and Leucocytozoon prevalence was higher in species resident on both continents and African residents than in migrants and Eurasian residents. Haemoproteus prevalence was lower in Eurasian residents than species resident on both continents. Our findings contrast with previous findings in the North-South American flyway, where long-distance migrants had higher parasite diversity than residents and short-distance migrants, although we found contrasting patterns for parasite diversity to those seen for parasite prevalence. Crucially, our results suggest that geographic range may be more important than migratory strategy in driving parasite diversity within species along the African-Palaearctic flyway. Our findings differ between the three parasite genera included in our analysis, suggesting that vector ecology may be important in determining these large-scale patterns. Our results add to our understanding of global patterns in parasite diversity and abundance, and highlight the need to better understand the influence of vector ecology to understand the drivers of infection risk and predict responses to environmental change.

Generation time and seasonal migration explain variation in spatial population synchrony across European bird species.

Spatial population synchrony is common among populations of the same species and is an important predictor of extinction risk. Despite the potential consequences for metapopulation persistence, we still largely lack understanding of what makes one species more likely to be synchronized than another given the same environmental conditions. Generally, environmental conditions in a shared environment or a species' sensitivity to the environment can explain the extent of synchrony. Populations that are closer together experience more similar fluctuations in their environments than those populations that are further apart and are therefore more synchronized. The relative importance of environmental and demographic stochasticity for population dynamics is strongly linked to species' life-history traits, such as pace of life, which may impact population synchrony. For populations that migrate, there may be multiple environmental conditions at different locations driving synchrony. However, the importance of life history and migration tactics in determining patterns of spatial population synchrony have rarely been explored empirically. We therefore hypothesize that increasing generation time, a proxy for pace of life, would decrease spatial population synchrony and that migrants would be less synchronized than resident species. We used population abundance data on breeding birds from four countries to investigate patterns of spatial population synchrony in growth rate and abundance. We calculated the mean spatial population synchrony between log-transformed population growth rates or log-transformed abundances for each species and country separately. We investigated differences in synchrony across generation times in resident (n = 67), short-distance migrant (n = 86) and long-distance migrant (n = 39) bird species. Species with shorter generation times were more synchronized than species with longer generation times. Short-distance migrants were more synchronized than long-distance migrants and resident birds. Our results provide novel empirical links between spatial population synchrony and species traits known to be of key importance for population dynamics, generation time and migration tactics. We show how these different mechanisms can be combined to understand species-specific causes of spatial population synchrony. Understanding these specific drivers of spatial population synchrony is important in the face of increasingly severe threats to biodiversity and could be key for successful future conservation outcomes.

Diverse migration patterns and seasonal habitat use of Stone's sheep (Ovis dalli stonei).

We describe temporal and spatial patterns of seasonal space-use and migration by 16 GPS-collared Stone's sheep (Ovis dalli stonei) from nine bands in the Cassiar Mountains of northern British Columbia, Canada. Our objectives were to identify the timing of spring and fall migrations, characterize summer and winter ranges, map and describe migration routes and use of stopover sites, and document altitudinal change across seasons. Our last objective was to assess individual migration strategies based on patterns of geographic migration, altitudinal migration, or residency. Median start and end dates of the spring migration were 12 and 17 Jun (range: 20 May to 05 Aug), and of the fall migration were 30 Aug and 22 Sep (range: 21 Aug to 07 Jan). The median area of winter and summer ranges for geographic migrants were 630.8 ha and 2,829.0 ha, respectively, with a broad range from about 233.6 to 10,196.2 ha. Individuals showed high fidelity to winter ranges over the limited duration of the study. The winter and summer ranges of most individuals (n=15) were at moderate to high elevations with a median summer elevation of 1,709 m (1,563-1,827 m) and 1,673 m (1,478-1,751 m) that varied <150 m between ranges. Almost all collared females (n=14) exhibited changes in elevation use that coincide with abbreviated altitudinal migration. Specifically, these females descended to lower spring elevations from their winter range (Δ>150 m), and then gradually moved up to higher-elevation summer ranges (Δ>150 m). In the fall, they descended to lower elevations (Δ>100 m) before returning to their higher winter ranges. The median distance travelled along geographic migration routes was 16.3 km (range: 7.6-47.4 km). During the spring migration, most geographic migrants (n=8) used at least one stopover site (median = 1.5, range: 0-4), while almost all migrants (n=11) used stopover sites more frequently in the fall (median = 2.5, range: 0-6). Of the 13 migratory individuals that had at least one other collared individual in their band, most migrated at about the same time, occupied the same summer and winter ranges, used similar migration routes and stopover sites, and exhibited the same migration strategy. We found collared females exhibited four different migration strategies which mostly varied across bands. Migration strategies included long-distance geographic migrants (n=5), short-distance geographic migrants (n=5), vacillating migrants (n=2), and abbreviated altitudinal migrants (n=4). Different migratory strategies occurred within one band where one collared individual migrated and two did not. We conclude that female Stone's sheep in the Cassiar Mountains displayed a diverse assemblage of seasonal habitat use and migratory behaviors. By delineating seasonal ranges, migration routes and stopover sites, we identify potential areas of priority that can help inform land-use planning and preserve the native migrations of Stone's sheep in the region.

Carry-Over Effects of Climate Variability at Breeding and Non-Breeding Grounds on Spring Migration in the European Wren Troglodytes troglodytes at the Baltic Coast.

Many studies have linked changes in avian phenology in Europe to the North Atlantic Oscillation (NAO), which serves as a proxy for conditions in western Europe. However, the effects of climate variation in other regions of Europe on the phenology of short-distance migrants with large non-breeding grounds remain unclear. We determined the combined influence of large-scale climate indices, NAO, the Mediterranean Oscillation Index (MOI), and the Scandinavian Pattern (SCAND), during the preceding year on spring migration timing of European wren at the southern Baltic coast during 1982-2021. We modelled the effects of these climate variables on the entire passage and subsequent percentiles of the wren's passage at Bukowo-Kopań and Hel ringing stations. Over 1982-2021, the start and median of migration shifted earlier at Hel, but the end of passage shifted later at both stations. In effect, the duration of passage at Hel was extended by 7.6 days. Early passage at Hel was related with high MOI in spring and the preceding autumn. Spring passage at Bukowo-Kopań was delayed after high NAO in the previous breeding season, and high winter and spring NAO. Late spring passage occurred at both stations following a high SCAND in the previous summer. At both locations, an early start or median of passage followed high local temperatures. We conclude that phenology of the wren's spring migration at the Baltic coast was shaped by conditions encountered at wintering quarters in western Europe, where NAO operates, and in the south-eastern Europe, where the MOI operates, in conjunction with conditions in Scandinavia during the previous breeding season. We demonstrated that climate variability in various parts of the migrants' range has combined carry-over effects on in migrants' phenology in Europe.

Seasonal patterns of bird and bat collision fatalities at wind turbines.

Information on when birds and bats die from collisions with wind turbines can help refine efforts to minimize fatalities via curtailment of energy productions and can offer insight into the risk factors associated with collision fatalities. Using data pooled from 114 post-construction monitoring studies conducted at wind facilities across the United States, we described seasonal patterns of fatalities among birds and bats. Bat fatalities peaked in the fall. Silver-haired bat (Lasionycteris noctivagans), a long-distance migrant, and Mexican free-tailed bat (Tadarida brasiliensis) both showed maximum fatality counts later in the year-October and November, respectively-than any other bat species. The other common species in our sample-hoary bat (Aeorestes cinereus), Eastern red bat (Lasiurus borealis), and big brown bat (Eptesicus fuscus)-showed broadly overlapping peaks of fatality counts in August. Fatalities of silver-haired bat showed a smaller spring peak in some ecoregions; no other bat species exhibited this pattern. Seasonal patterns of bird fatalities varied among guilds. Woodland birds, many of which were long-distance migrants, showed two peaks in fatalities corresponding to spring and fall migration. Grassland birds and soaring birds, most of which were resident or short-distance migrants, did not exhibit strong seasonal peaks in fatalities. Species in these guilds tend to inhabit regions with extensive wind-energy development year-round, which may explain the more consistent numbers of fatalities that we observed. Our results highlight the value of pooling data to develop science-based solutions to reduce conflicts between wind-energy development and wildlife but also emphasize the need for more extensive data and standardization of post-construction monitoring to support more robust inferences regarding wind-wildlife interactions and collision risk.

The using of data on the moult progress in the study of migration periods of the annual cycle of passerines

Using trapping and ringing of birds for studying the ecology and the demographic parameters of populations is necessary to determine as accurately as possible in which period of the annual cycle each individual was caught. The first-year passerine birds undergo juvenile migration (usually in form of postfledging dispersal) and postmoulting (autumn) migration in summer-autumn period. These stages of annual cycle are difficult to identify in trapping birds by calendar dates because the timing of migration seasons can significantly overlap in the same location. The study of moult at the Ladoga Ornithological Station made it possible to determine the states of plumage that mark juvenile and postmoulting migrations in first-year birds. The article presents two examples of the use of moult progress in the study of bird migrations. The first one is an analysis of the ratio of the terms of departure and passage in three long-distant and three short-distant migrants of passerines. It has been shown that the timing of the departure of local birds is earlier than the timing of the passage of other populations in all studied species, while the last local individuals in long-distance migrants are recorded long before the end of the passage of the species, and in short-distance migrants they can be found until its end. As another example, an analysis of long-term trends in the timing of summer-autumn movements in the Garden Warbler was performed. It is shown that for almost a fifty-year observation period, neither the timing of juvenile migration nor the timing of postmoulting migration of first-year birds has changed. At the same time, the timing of the spring passage of the species shifted to earlier. As a result, the duration of stay of the Garden Warbler in the Ladoga region has increased.