Animal migration Research Papers - Academia.edu (original) (raw)

2025, Archaeometry

Strontium (Sr) isotope ratios (87Sr/86Sr) measured in human skeletal material can increase one's understanding of the residential behaviour and resource‐acquisition strategies of past populations. The paper maps bioavailable 87Sr/86Sr variation in 183 plant and soil samples across Cambodia. Bioavailable 87Sr/86Sr, as measured in plants, differs significantly between four major geological units. The data set will support future investigations of skeletal material from Cambodian archaeological sites. Baseline 87Sr/86Sr data should be applied judiciously to skeletal populations, and in concert with other lines of evidence, to identify potential geographical outliers rather than to ascribe specific locations from which individuals may have moved.

2025, The American Naturalist

Rapid environmental change is affecting many organisms; some are coping well but many species are in decline. A key mechanism for facilitating success following environmental change is phenotypic plasticity. Organisms use cues to respond phenotypically to environmental conditions; many incorporate recent information (within-generation plasticity) and information from previous generations (transgenerational plasticity). We extend an existing evolutionary model where organisms utilize within-generational plasticity, transgenerational plasticity, rapid evolution, and bet-hedging. We show how, when rapid evolution of plasticity is not possible, the effect of environmental change (altering the environment mean, variance, or autocorrelation, or cue reliability) on population growth rate depends on selection for within-generation plasticity and transgenerational plasticity under historical environmental conditions. We then evaluate the predictions that populations adapted to highly variable environments, or with greater withingenerational plasticity, are more likely to successfully respond to environmental change. We identify when these predictions fail, and show environmental change is most detrimental when previously reliable cues become unreliable. When multiple cues become unreliable, environmental change can cause deleterious effects regardless of the population's evolutionary history. Overall, this work provides a general framework for understanding the role of plasticity in population responses to rapid environmental change.

2025, Molecular Ecology

Drosophila subobscura is a Palearctic species that was first observed in South and North America in the early 1980s, and that rapidly invaded broad latitudinal ranges on both continents. To trace the source and history of this invasion, we obtained genotypic data on nine microsatellite loci from two South American, two North American and five European populations of D. subobscura. We analysed these data with traditional statistics as well as with an approximate Bayesian computation (ABC) framework. ABC methods yielded the strongest support for the scenario involving a serial introduction with founder events from Europe into South America, and then from South America into North America. Stable effective population size of the source population was very large (around one million individuals), and the propagule size was notably smaller for the introduction into South America (i.e. high bottleneck severity index with only a few effective founders) but considerably larger for the subsequent introduction into North America (i.e. low bottleneck severity index with around 100 -150 effective founders). Finally, the Mediterranean region of Europe (and most likely Barcelona from the localities so far analysed) is proposed as the source of the New World flies, based on mean individual assignment statistics.

2025, Heredity

The Palaearctic species Drosophila subobscura recently invaded the west coast of Chile and North America. This invasion helped to corroborate the adaptive value of the rich chromosomal polymorphism of the species, as the same clinal patterns than those observed in the original Palaearctic area were reproduced in the colonized areas in a relatively short period of time. The rapid response of this polymorphism to environmental conditions makes it a good candidate to measure the effect of the global rising of temperatures on the genetic composition of populations. Indeed, the long-term variation of this polymorphism shows a general increase in the frequency of those inversions typical of low latitudes, with a corresponding decrease of those typical of populations closer to the poles. Although the mechanisms underlying these changes are not well understood, the system remains a valid tool to monitor the genetic impact of global warming on natural populations.

2025, Philosophical Transactions of the Royal Society B: Biological Sciences

The annual life cycle of many birds includes breeding, moult and migration. All these processes are time and energy consuming and the extent of investment in any one may compromise the others. The output from breeding is of course the ultimate goal for all birds, while the investment in moult and migration should be selected so that lifetime fitness is maximized. In particular, long-distance migrants breeding at high latitudes face severe time pressures, which is a probable reason why natural selection has evolved efficient behaviours, physiological and morphological adaptations allowing the maximum possible migration speed. Optimal migration theory commonly assumes time minimization as an overall strategy, but the minimization of energy cost and predation risk may also be involved. Based on these assumptions, it is possible to derive adaptive behaviours such as when and at which fuel load a stopover site should be abandoned. I review some core components of optimal migration theory...

2025, PLoS ONE

Even with global support for tiger (Panthera tigris) conservation their survival is threatened by poaching, habitat loss and isolation. Currently about 3,000 wild tigers persist in small fragmented populations within seven percent of their historic range. Identifying and securing habitat linkages that connect source populations for maintaining landscape-level gene flow is an important long-term conservation strategy for endangered carnivores. However, habitat corridors that link regional tiger populations are often lost to development projects due to lack of objective evidence on their importance. Here, we use individual based genetic analysis in combination with landscape permeability models to identify and prioritize movement corridors across seven tiger populations within the Central Indian Landscape. By using a panel of 11 microsatellites we identified 169 individual tigers from 587 scat and 17 tissue samples. We detected four genetic clusters within Central India with limited gene flow among three of them. Bayesian and likelihood analyses identified 17 tigers as having recent immigrant ancestry. Spatially explicit tiger occupancy obtained from extensive landscape-scale surveys across 76,913 km 2 of forest habitat was found to be only 21,290 km 2 . After accounting for detection bias, the covariates that best explained tiger occupancy were large, remote, dense forest patches; large ungulate abundance, and low human footprint. We used tiger occupancy probability to parameterize habitat permeability for modeling habitat linkages using least-cost and circuit theory pathway analyses. Pairwise genetic differences (F ST ) between populations were better explained by modeled linkage costs (r.0.5, p,0.05) compared to Euclidean distances, which was in consonance with observed habitat fragmentation. The results of our study highlight that many corridors may still be functional as there is evidence of contemporary migration. Conservation efforts should provide legal status to corridors, use smart green infrastructure to mitigate development impacts, and restore habitats where connectivity has been lost.

2025, Ticks and tick-borne diseases

Seasonal migration of passerine birds between temperate North America and tropical Central and South America is an ecological phenomenon. Migration of birds has been associated with the introduction of ectoparasites like ticks or tick-borne pathogens across the avian migration routes. In this study, the microbial diversity was determined in the ticks and bird DNA samples using 454 pyrosequencing of bacterial 16S rRNA gene. Tick DNA samples showed the dominance of genera Lactococcus, Francisella, Raoultella, Wolbachia and Rickettsia across all the ticks, but birds DNA did not share common microbial diversity with ticks. Furthermore, "Candidatus Rickettsia amblyommii" infection in the 91 ticks collected off the songbirds was also quantified by qPCR assay. Interestingly, "Candidatus R. amblyommii" was tested positive in 24 ticks (26% infection), and infection varied from as low as three copies to thousands of copies, but bird blood samples showed no amplification. O...

2025, Hydrobiologia

Diel vertical migration (DVM) behaviour is a predator avoidance mechanism observed within many zooplankton species in the presence of zooplanktivorous fish. A 24-h survey was carried out in June 1998 to investigate diel variation in the vertical distribution of fish, zooplankton and phytoplankton (chlorophyll) in Lake Kinneret, Israel. Fish revealed diel variation in vertical distribution but had no spatial overlap with zooplankton, and consequently no apparent influence on zooplankton dispersal. Zooplankton revealed some diel variation in distribution being affected by thermocline and oxycline position and movement of the internal the internal seiche wave. Cyclopoid species closely follow the movement of the seiche wave implying that, due to their greater motility, they are following conditions that are suitable to them. The Cladocera species and small rotifers only partly, which may be part of their phototaxic behaviour. Physical forces like convection, horizontal and vertical forcing probably have a role in contributing to a homogeneous distribution of the plankton by preventing stratification or interfering with the more motile zooplankton which may be attempting to migrate.

2025

Movement ecology is an important tool for understanding animal behaviour toward basic needs, as well as to design conservation and management priorities. Animals usually do not move randomly and may prefer certain types of habitats over others. The yellow anaconda (Eunectes notaeus) is one of the largest snakes in South America. However, little is known about its natural history. Here, we present results from a telemetry study to quantify movement patterns and habitat use of eight yellow anacondas in a protected, seasonally flooded area in Midwestern Brazil. Yellow anacondas were associated to small channels with macrophyte stands and bushy vegetation. They moved relatively little (188 m monthly) and had small home range (mean 6.2 ha); they used native pastures and abandoned farmlands with forest patches more than expected by chance. Our results contribute to the understanding of dispersal patterns, habitat choices, and life history of this large aquatic snake and to the body of kno...

2025, Journal of Ornithology

The evolutionary history of three out of four birds traditionally classified into the genus Rhodopechys birds has been studied by comparing their mitochondrial cytochrome b DNA sequence with that of greenfinches and other genus Carduelis finches. The desert finch (Rhodopechys obsoleta) or a sister extinct species seems to have existed about 6 million years ago in Asian and perhaps African desert-like areas. This bird has no molecular relationship with other Rhodopechys birds and seems to have given rise to the greenfinches radiation, probably by allopatry of marginal or isolated groups; the latter would have evolved to green plumage colours and more simple song modulations (i.e., greenfinches). The possible role of assortative mating and the newly postulated acquired phenotypic characters in greenfinches speciation are discussed.

2025, PloS one

A novel avian paramyxovirus (APMV) isolated from a migratory bird cloacal swab obtained during active surveillance in April 2012 in the Lagoa do Peixe National Park, Rio Grande do Sul state, South of Brazil was biologically and genetically characterized. The nucleotide sequence of the full viral genome was completed using a next-generation sequencing approach. The genome was 14,952 nucleotides (nt) long, with six genes (3'-NP-P-M-F-HN-L-5') encoding 7 different proteins, typical of APMV. The fusion (F) protein gene of isolate RS-1177 contained 1,707 nucleotides in a single open reading frame encoding a protein of 569 amino acids. The F protein cleavage site contained two basic amino acids (VPKER↓L), typical of avirulent strains. Phylogenetic analysis of the whole genome indicated that the virus is related to APMV-10, -2 and -8, with 60.1% nucleotide sequence identity to the closest APMV-10 virus, 58.7% and 58.5% identity to the closest APMV-8 and APMV-2 genome, respectively,...

2025, PLOS ONE

A dramatic expansion of road building is underway in the Congo Basin fuelled by private enterprise, international aid, and government aspirations. Among the great wilderness areas on earth, the Congo Basin is outstanding for its high biodiversity, particularly mobile megafauna including forest elephants (Loxodonta africana cyclotis). The abundance of many mammal species in the Basin increases with distance from roads due to hunting pressure, but the impacts of road proliferation on the movements of individuals are unknown. We investigated the ranging behaviour of forest elephants in relation to roads and roadless wilderness by fitting GPS telemetry collars onto a sample of 28 forest elephants living in six priority conservation areas. We show that the size of roadless wilderness is a strong determinant of home range size in this species. Though our study sites included the largest wilderness areas in central African forests, none of 4 home range metrics we calculated, including core area, tended toward an asymptote with increasing wilderness size, suggesting that uninhibited ranging in forest elephants no longer exists. Furthermore we show that roads outside protected areas which are not protected from hunting are a formidable barrier to movement while roads inside protected areas are not. Only 1 elephant from our sample crossed an unprotected road. During crossings her mean speed increased 14-fold compared to normal movements. Forest elephants are increasingly confined and constrained by roads across the Congo Basin which is reducing effective habitat availability and isolating populations, significantly threatening long term conservation efforts. If the current road development trajectory continues, forest wildernesses and the forest elephants they contain will collapse.

2025, Emerging Infectious Diseases

To understand the emergence of vaccinia virus Cantagalo strain in the Amazon biome of Brazil, during 2008-2010 we conducted a molecular and epidemiologic survey of poxvirus outbreaks. Data indicate that animal movement was the major cause of virus dissemination within Rondônia State, leading to the establishment and spread of this pathogen. O utbreaks of vaccinia virus (VACV) infection in dairy cows and dairy workers have been frequently reported in Brazil during the past decade, mainly within the southeastern region (1-6), except for central Goiás (2) and Tocantins State in the northeastern boundary of the Brazilian Amazon biome (Figure ) (7). VACV Cantagalo strain (CTGV) was fi rst detected in 1999 and associated with several outbreaks (1,5,7). Related strains have been reported in subsequent outbreaks . Mato Grosso State is partially inserted into the southeastern Amazon biome (Figure ) and has the largest cattle population of Brazil, ≈26 million (8). It is the main connection with the Amazon states, especially with Rondônia. Rondônia has nearly 11.2 million cattle and is the largest milk producer in the region, yielding >720 million liters/year (8). Therefore, intense livestock trade occurs through the so-called Amazon Gate of Mato Grosso and Rondônia. Both states had previously been considered poxvirus disease-free. From June 2008 through June 2010, we investigated outbreaks of poxvirus-related disease on 56 dairy farms of Mato Grosso and Rondônia (Figure ). A probable case was defi ned as illness observed in any cattle from these farms that showed clinical signs consistent with a poxvirus-

2025, Journal of Fish Biology

Adult sockeye salmon Oncorhynchus nerka destined for the Fraser River, British Columbia are some of the most economically important populations but changes in the timing of their homeward migration have led to management challenges and conservation concerns. After a directed migration from the open ocean to the coast, this group historically would mill just off shore for 3–6 weeks prior to migrating up the Fraser River. This milling behaviour changed abruptly in 1995 and thereafter, decreasing to only a few days in some years (termed early migration), with dramatic consequences that have necessitated risk‐averse management strategies. Early migrating fish consistently suffer extremely high mortality (exceeding 90% in some years) during freshwater migration and on spawning grounds prior to spawning. This synthesis examines multidisciplinary, collaborative research aimed at understanding what triggers early migration, why it results in high mortality, and how fisheries managers can ut...

2025, American Journal of Tropical Medicine and Hygiene

Bird collections. Migratory and resident birds were captured while transiting sites on the northeastern (35.51, -115.92) and northwestern (33.46, -116.06) shores of the Salton Sea, Coachella Valley, Riverside County, CA, from 1996 through 2005. In addition, migratory transients were targeted during collections made during the springs of 2006 and 2007. Migrants and other birds also were collected during 1996 through 2008 in Kern County, primarily from wetlands at the Kern National Wildlife Refuge (35.73, -119.63) and the Kern River (35.32, -119.20). The ecology of these areas, descriptions of arbovirus activity, and bird sampling methods have been described previously. Briefly, birds were collected using multiple mist nets and grain-baited traps. Mist nets were 10 m long × 2.5 m tall and had 28-, 32-, or 60-mm mesh depending on the target species. Captured birds were banded with U.S. Geological Survey (USGS) bands, aged, sexed, and a 0.1 mL sample of blood collected from the jugular vein with 28-g needles. For antibody detection, blood samples were expelled into 0.9 mL of 0.9% saline solution, clarified through centrifugation, and stored at -70°C. During 2004, 2006, and 2007 blood samples from migratory species collected in Coachella Valley were expelled into 0.4 mL of virus diluent (phosphate buffered saline, 15% fetal bovine sera, antibiotics) and tested for infectious virus and antibody. Data from the California WNV Dead Bird Surveillance Program 24 on neotropical migrants that were found dead by the public, sent for necropsy, and tested positive for WNV RNA were included for comparison. Experimental infection. Four warbler species commonly included in our field collections were experimentally infected

2025, BMC Evolutionary Biology

2025, Physiology & Behavior

When animals are reared for conservational releases it is paramount to avoid reducing genetic and phenotypic variation over time. This requires an understanding of how diverging behavioural and physiological traits affect performance both in captivity and after release. In Atlantic salmon, emergence time from the spawning gravel has been linked to certain behavioural and physiological characteristics and to the concept of stress coping styles. Early emerging fry has for example been shown to be bolder and more aggressive and to have higher standard metabolic rates compared to late emerging fry. The first aim was therefore to examine if emergence latency affect the behavioural stress coping response also beyond the fry and parr stage. This was done using a hypoxia avoidance test, where an active behavioural avoidance response can be related to higher risk taking. No behavioural differences were

2025

The property managed by Eglin Air Force Base (EAFB) along Cape San Bias is a unique ecosystem, from the dynamics of the landscape to the plant and animal communities utilizing the habitats. In addition to being an extraordinarily dynamic system, this area supports several threatened and endangered species including the loggerhead sea turtle (Caretta caretta), Piping Plover (Charadrius melodus), and Snowy Plover (Charadrius alexandrinus). This system therefore, represents a natural laboratory and a unique opportunity to examine effects of coastal erosion and accretion on biological communities. Formation and maintenance of barrier islands require abundant sand supplies. Since present sea level has stabilized in the past 4,000 to 5,000 years, there has been very little new sand added to barrier islands along the northern Gulf of Mexico. The result is that portions of these barrier islands are being eroded by several forces, thus creating extraordinarily dynamic systems . Species that rely on these systems for survival must cope with these changes if long-term use of barrier islands is required. One group of animals dependent upon barrier islands are nesting sea turtles. OBJECTIVES OF PROJECT (maximum 4000 characters):

2025, PLOS ONE

Consistent individual differences in behaviour have been well documented in a variety of animal taxa, but surprisingly little is known about the fitness and life-history consequences of such individual variation. In wild salmonids, the timing of fry emergence from gravel spawning nests has been suggested to be coupled with individual behavioural traits. Here, we further investigate the link between timing of spawning nest emergence and behaviour of Atlantic salmon (Salmo salar), test effects of social rearing environment on behavioural traits in fish with different emergence times, and assess whether behavioural traits measured in the laboratory predict growth, survival, and migration status in the wild. Atlantic salmon fry were sorted with respect to emergence time from artificial spawning nest into three groups: early, intermediate, and late. These emergence groups were hatchery-reared separately or in co-culture for four months to test effects of social rearing environment on behavioural traits. Twenty fish from each of the six treatment groups were then subjected to three individual-based behavioural tests: basal locomotor activity, boldness, and escape response. Following behavioural characterization, the fish were released into a near-natural experimental stream. Results showed differences in escape behaviour between emergence groups in a net restraining test, but the social rearing environment did not affect individual behavioural expression. Emergence time and social environment had no significant effects on survival, growth, and migration status in the stream, although migration propensity was 1.4 to 1.9 times higher for early emerging individuals that were reared separately. In addition, despite individuals showing considerable variation in behaviour across treatment groups, this was not translated into differences in growth, survival, and migration status. Hence, our study adds to the view that fitness (i.e., growth and survival) and life-history

2025, Journal of Avian Biology

Factors outside the breeding season can affect population trends for migratory species. Yet information on population-specific migration and nonbreeding ecology for most species is lacking, complicating conservation efforts. Louisiana waterthrush Parkesia motacilla and worm-eating warblers Helmitheros vermivorum are Nearctic-Neotropical migratory songbirds that share breeding habitat associations, and occur in sympatry throughout most of their breeding distributions. Yet these species exhibit variable regional population trends on the breeding grounds, suggesting that processes outside of the breeding period may impact population growth. We used light-level geolocators to track Louisiana waterthrush and worm-eating warblers from four sites spanning their breeding distributions (Arkansas, Tennessee, Ohio, and Pennsylvania, USA). We describe the geographic distribution of populations during the nonbreeding period and quantify interspecific variation in the timing of migration to assess the potential for factors outside the breeding period to impact population dynamics. From 2016 to 2020, we marked 153 individuals (85 Louisiana waterthrush and 68 worm-eating warblers) across the four sites, and estimated migration timing, nonbreeding locations, and migratory connectivity for 24 Louisiana waterthrush and 21 worm-eating warblers. We observed moderately strong migratory connectivity (MC) in both species (Louisiana waterthrush MC = 0.40 [0.25 SE], worm-eating warbler MC = 0.44 [0.13 SE]) between breeding and nonbreeding sites, and a high degree of overlap (i.e. > 50%) among most populations' nonbreeding core-use areas. Moreover, populations experienced largely similar environmental conditions (measured by enhanced vegetation index) during the nonbreeding period. On average, Louisiana waterthrush initiated migration ~ 40 days earlier than worm-eating warblers across the annual cycle, and this trend was strongest in southern breeding populations. These findings emphasize the value of leveraging multiple species into full-annual cycle studies to identify

2025, The Condor

The ability to satisfy the energy requirements of migration and to cope with problems that arise en route is likely to be age dependent. We studied hatch-year (HY) and after-hatch-year (AHY) Gray Catbirds (Dumetella carolinensis) to determine if differences in foraging efficiency and molt affected fat deposition prior to autumn migration. Hatchyear catbirds were less efficient foragers than AHY catbirds; however, efficiency improved with age to the extent that many HY catbirds are probably as efficient as AHY birds by the time they commence migration. We discovered age-dependent patterns of fat deposition, which probably resulted from differences in foraging efficiency and molt timing. Hatch-year catbirds began to deposit fat sooner than AHY catbirds but did so more slowly throughout the postbreeding and premigratory phases of the annual cycle. Adult catbirds did not become hyperphagic until they neared the completion of their molt, then deposited fat rapidly.

2025, General and comparative endocrinology

Preparation for breeding may overlap extensively with vernal migration in long-distance migratory songbirds. Testosterone plays a central role in mediating this transition into breeding condition by facilitating changes to physiology and behavior. While changes in testosterone levels are well studied in captive migrants, these changes are less well known in free-living birds. We examined testosterone levels in free-living Nearctic-Neotropical migrants of three species during their vernal migration. Testosterone levels increased during the migratory period in males of all three species but significantly so in only two. Testosterone levels in females remained the same throughout their migration. Our results support the extensive overlap between vernal migration and breeding preparation in male songbirds. The pattern of testosterone changes during vernal migration is far from clear in females.

2025, Proceedings of the National Academy of Sciences

Significance Bird migration has captivated the attention of scientists and lay people for centuries, but many unanswered questions remain about how birds negotiate large geographic features during migration. We tracked songbirds across the Gulf of Mexico to investigate the factors associated with birds’ departure decisions, arrival at the Yucatan Peninsula (YP), and crossing times. Our findings suggest that a bird’s fat reserves and low humidity, indicative of favorable synoptic weather patterns, shape departure decisions. Fat, date, and wind conditions predict birds’ detection in the YP. This study highlights the complex decision-making process involved in crossing the Gulf and its effects on migratory routes and speeds. A better understanding of the factors influencing migration across these features will inform conservation of migratory animals.

2025, PLoS ONE

Movement patterns during songbird migration remain poorly understood despite their expected fitness consequences in terms of survival, energetic condition and timing of migration that will carry over to subsequent phases of the annual cycle. We took an experimental approach to test hypotheses regarding the influence of habitat, energetic condition, time of season and sex on the hour-by-hour, local movement decisions of a songbird during spring stopover. To simulate arrival of nocturnal migrants at unfamiliar stopover sites, we translocated and continuously tracked migratory red-eyed vireos (Vireo olivaceus) throughout spring stopover with and without energetic reserves that were released in two replicates of three forested habitat types. Migrants moved the most upon release, during which time they selected habitat characterized by greater food abundance and higher foraging attack rates. Presumably under pressure to replenish fuel stores necessary to continue migration in a timely fashion, migrants released in poorer energetic condition moved faster and further than migrants in better condition and the same pattern was true for migrants released late in spring relative to those released earlier. However, a migrant's energetic condition had less influence on their behavior when they were in poor quality habitat. Movement did not differ between sexes. Our study illustrates the importance of quickly finding suitable habitat at each stopover site, especially for energetically constrained migrants later in the season. If an initial period prior to foraging were necessary at each stop along a migrant's journey, non-foraging periods would cumulatively result in a significant energetic and time cost to migration. However, we suggest behavior during stopover is not solely a function of underlying resource distributions but is a complex response to a combination of endogenous and exogenous factors.

2025, The Condor

Whereas endogenous time programs are thought to control different aspects of bird migration, regulation of migratory behavior is sensitive to acute ecological factors. The relation between migratory activity and energetic status was studied by monitoring day (presumptive feeding) and night (migratory) locomotor activity of captive North American thrushes (Hylocichla mustelina, Catharus fuscescens, C. ustulatus, and C. minimus) immediately after spring passage across the Gulf of Mexico. (1) Lean migrants, regardless of species, displayed less night activity than migrants with undepleted fat stores. (2) Lean birds were more active during the day (presumptive feeding behavior) than fat birds, regardless of species. (3) Nocturnal restlessness resumed as lean individuals replenished fat stores, whereas day activity decreased as lean birds regained mass. (4) Cutharus thrushes, which travel longer distances than Wood Thrushes before reaching breeding grounds, displayed more activity on a per-night basis. Our results support the idea that a migrant' s energetic status modifies the programmed course of migration.

2025, The Auk

We estimated fat load, length of stopover, and rate of mass change for six Neotropical migrant landbird species at a site along the northern coast of the Gulf of Mexico. Swainson's Thrushes (Catharus ustulatus), Gray Catbirds (Dumetella carolinensis), White-eyed Vireos (Vireo griseus), Red-eyed Vireos (V. olivaceus), Magnolia Warblers (Dendroica magnolia), and American Redstarts (Setophaga ruticilla) were captured on Fort Morgan Peninsula in coastal Alabama during fall migration, 1990 to 1992. In Swainson's Thrushes, White-eyed Vireos, and American Redstarts, adults carried significantly higher fat loads than young birds, whereas no age-related differences in fat loads were evident in the other species. The likelihood of staying beyond the day of capture and the rate of change in body mass did not differ between age classes. One consequence of differences in fat load is reflected in flight range in relation to the Gulf of Mexico. On average, adult Swainson's Thrushes, White-eyed Vireos, American Redstarts, and both age classes of Magnolia Warblers carried sufficient energy stores to complete a trans-Gulf flight, whereas young Swainson's Thrushes, Whiteeyed Vireos, American Redstarts and both age classes of Gray Catbirds carried insufficient stores for such a flight, based on flight-performance simulations.

2025, Scientific Reports

Over decades it has been unclear how individual migratory songbirds cross large ecological barriers such as seas or deserts. By deploying light-level geolocators on four songbird species weighing only about 12 g, we found that these otherwise mainly nocturnal migrants seem to regularly extend their nocturnal flights into the day when crossing the Sahara Desert and the Mediterranean Sea. The proportion of the proposed diurnally flying birds gradually declined over the day with similar landing patterns in autumn and spring. The prolonged flights were slightly more frequent in spring than in autumn, suggesting tighter migratory schedules when returning to breeding sites. Often we found several patterns for barrier crossing for the same individual in autumn compared to the spring journey. As only a small proportion of the birds flew strictly during the night and even some individuals might have flown nonstop, we suggest that prolonged endurance flights are not an exception even in small migratory species. We emphasise an individual's ability to perform both diurnal and nocturnal migration when facing the challenge of crossing a large ecological barrier to successfully complete a migratory journey.

2025, Proceedings of The Royal Society B: Biological Sciences

Billions of songbirds breeding in the Western Palaearctic cross the largest desert of the world, the Sahara, twice a year. While crossing Europe, the vast majority use an intermittent flight strategy, i.e. fly at night and rest or feed during the day. However, it was long assumed that they overcome the Sahara in a 40 h non-stop flight. In this study, we observed bird migration with radar in the plain sand desert of the Western Sahara (Mauritania) during autumn and spring migration and revealed a clear prevalence of intermittent migration. Massive departures of songbirds just after sunset independent of site and season suggests strongly that songbirds spent the day in the plain desert. Thus, most songbirds cross the Sahara predominately by the intermittent flight strategy. Autumn migration took place mainly at low altitudes with high temperatures, its density decreased abruptly before sunrise, followed by very little daytime migration. Migration was highly restricted to night-time and matched perfectly the intermittent flight strategy. However, in spring, when migratory flights occurred at much higher altitudes than in autumn, in cool air, about 17% of the songbird migration occurred during the day. This suggests that flying in high temperatures and turbulent air, as is the case in autumn, may lead to an increase in water and/or energy loss and may prevent songbirds from prolonged flights into the day.

2025, Scientific Reports

Over decades it has been unclear how individual migratory songbirds cross large ecological barriers such as seas or deserts. By deploying light-level geolocators on four songbird species weighing only about 12 g, we found that these otherwise mainly nocturnal migrants seem to regularly extend their nocturnal flights into the day when crossing the Sahara Desert and the Mediterranean Sea. The proportion of the proposed diurnally flying birds gradually declined over the day with similar landing patterns in autumn and spring. The prolonged flights were slightly more frequent in spring than in autumn, suggesting tighter migratory schedules when returning to breeding sites. Often we found several patterns for barrier crossing for the same individual in autumn compared to the spring journey. As only a small proportion of the birds flew strictly during the night and even some individuals might have flown non-stop, we suggest that prolonged endurance flights are not an exception even in smal...

2025, Journal of Experimental Biology

SUMMARYBirds adjust their flight behaviour to the physical properties of the air. Lift and drag, the two major properties in aerodynamics, are highly dependent on air density. With decreasing air density drag is reduced and lift per wingbeat decreases. According to flight mechanical theory, wingbeat frequency and air speed should increase with decreasing air density, i.e. increasing flight altitude. Although wind tunnel experiments have shed light on many aspects of avian flight, the effect of air density remained ambiguous, because air density could not be adjusted in wind tunnels, until now. By means of radar we recorded tracks of several thousand free-flying individual birds during nocturnal migration. From these tracks we derived wingbeat frequencies and air speeds covering air densities from 0.84 kg m–3 to 1.13 kg m–3, corresponding to an altitudinal range of about 3000 m. We demonstrate here with this sample of nocturnal migrants that: (1)wingbeat frequency decreases with air ...

2025, Proceedings of the Royal Society B: Biological Sciences

2025

From 1 November 2013 to 30 April 2014 an avian radar system was operated in Tsavo West National Park, Kenya. The aim of this research was to study the temporal and spatial distribution of migrating birds over Ngulia Safari Lodge and to compare radar data with catching results of grounded birds. Additionally, the general pattern of flight directions during the six-month season is shown. From 25 November to 12 December 2013 more than 21 000 birds of 29 species were caught and ringed under misty conditions, supported by floodlights and sound luring (Pearson 2013). A total of 8564 individuals (41%) were caught during the night. The majority of the birds were Marsh Warblers Acrocephalus palustris (4442 ringed) and Thrush Nightingales Luscinia luscinia (2719). Radar data of bird migration intensities (migration traffic rates, MTR = birds/km/h) show an increase in late November to December, decreasing towards February and rising again in March and April when birds are migrating north to th...

2025

One of the most distinctive aspects of the Connecticut College Arboretum has been our focus on the importance of long-term ecological research. Detailed studies of natural vegetation and bird communities began shortly after the establishment of the Bolleswood Natural Area in 1952. Since that time teams of faculty and students have documented the changes in these natural communities, and have shared the information generated from their studies in both technical and popular publications. The Arboretum Bulletin series has often served as a vehicle for disseminating Connecticut College original research to the general public, and the present edition is an excellent example of how to make scientific information accessible to a broad audience. The Arboretum map that is located in the center of this bulletin is the most accurate version we have ever produced. Generated in the College's Geographic Information Systems Lab, it details the wetlands, watercourses, topography, trails and stone walls with great clarity. This map was customized for this publication, and other digital and printable versions are available on the Arboretum website.

2025, PLoS ONE

The net movement of individuals from marine reserves (also known as no-take marine protected areas) to the remaining fishing grounds is known as spillover and is frequently used to promote reserves to fishers on the grounds that it will benefit fisheries. Here we consider how mismanaged a fishery must be before spillover from a reserve is able to provide a net benefit for a fishery. For our model fishery, density of the species being harvested becomes higher in the reserve than in the fished area but the reduction in the density and yield of the fished area was such that the net effect of the closure was negative, except when the fishery was mismanaged. The extent to which effort had to exceed traditional management targets before reserves led to a spillover benefit varied with rates of growth and movement of the model species. In general, for well-managed fisheries, the loss of yield from the use of reserves was less for species with greater movement and slower growth. The spillover benefit became more pronounced with increasing mis-management of the stocks remaining available to the fishery. This model-based result is consistent with the literature of field-based research where a spillover benefit from reserves has only been detected when the fishery is highly depleted, often where traditional fisheries management controls are absent. We conclude that reserves in jurisdictions with well-managed fisheries are unlikely to provide a net spillover benefit.

2025, Vector-Borne and Zoonotic Diseases

We sought to elucidate the role of migratory birds in transmission of H5N1 in an enzoonotic area. Resident, captive, and migratory birds were sampled at five sites in Java, Indonesia. Mist nets were used to trap birds. Birds were identified to species. RNA was extracted from swabs and reverse transcriptase polymerase chain reaction (RT-PCR) conducted for the HA and M genes of H5N1. Antibodies were detected by enzyme-linked immunosorbent assay and hemagglutination inhibition test. Between October 2006 and September 2007, a total of 4,067 captive, resident, and migratory birds comprising 98 species in 23 genera were sampled. The most commonly collected birds were the common sandpiper (6% of total), striated heron (3%), and the domestic chicken (14%). The overall prevalence of H5N1 antibodies was 5.3%. A significantly higher percentage of captive birds (16.1%) showed antibody evidence of H5N1 exposure when compared to migratory or resident birds. The greatest number of seropositive birds in each category were Muschovy duck (captive), striated heron (resident), and the Pacific golden plover (migratory). Seven apparently well captive birds yielded molecular evidence of H5N1 infection. Following amplification, the HA, NA, and M genes were analyzed. Phylogenetic analysis of the HA gene showed that the isolates were 97% similar to EU124153.1 A/chicken/West Java/Garut May 2006, an isolate obtained in a similar region of West Java. While no known markers of neuraminidase inhibitor resistance were found within the NA gene, M segment analysis revealed the V27A mutation known to confer resistance to adamantanes. Our results demonstrate moderate serologic evidence of H5N1 infection in captive birds, sampled in five sites in Java, Indonesia, but only occasional infection in resident and migratory birds. These data imply that in an enzoonotic region of Indonesia the role of migratory birds in transmission of H5N1 is limited.

2025

Western monarch butterflies (sp. Danaus plexippus) are undergoing a severe decline that rivals those occurring among insects across the globe. Despite the estimation of population abundance, growth rates, and extinction probabilities, no analyses have investigated spatiotemporal patterns of decline in the western monarch population. I performed occupancy modeling of Western Monarch Thanksgiving Count (WMTC) data. The data was constrained spatially and temporally, with sites grouped into occupancy bins by latitude and year. Occupancy probabilities (psi) were estimated for each intersection of a latitude and time bin and detection probabilities (p) were estimated for each time bin. Psi increased slightly and non-significantly from northern to southern latitude bins. However, the dataset was unable to support any models with >3 latitude bins or the intersection of latitude and time bins because the dataset contained unequal sampling distributions across both space and time and a hig...

2025, Proceedings. Biological sciences / The Royal Society

Bird migration is one of the most spectacular and best-studied phenomena in behavioural biology. Yet, while the patterns of variation in migratory behaviour and its ecological causes have been intensively studied, its genetic, physiological and neurological control remains poorly understood. The lack of knowledge of the molecular basis of migration is currently not only limiting our insight into the proximate control of migration, but also into its evolution. We investigated polymorphisms in the exons of six candidate genes for key behavioural traits potentially linked to migration, which had previously been identified in several bird species, and eight control loci in 14 populations of blackcaps (Sylvia atricapilla), representing the whole range of geographical variation in migration patterns found in this species, with the aim of identifying genes controlling variation in migration. We found a consistent association between a microsatellite polymorphism and migratory behaviour onl...

2025, canacacao.org

Cacao cultivation has been an important component of Central American culture and commerce since pre-Columbian times. However, during the last decades of the 20 th century, cacao production declined considerably in this region due to the dramatic impact of pod diseases, the low yield-potential of the plantations, and the frequent periods of low prices. An expansion of the activity is currently underway encouraged by the improvement of international and local prices and the increased interest in the markets for Trinitario cacaos, which are prevalent in Central America. Success of these renovated efforts will depend on the ability to overcome the main biotic factors limiting cacao production: the incidence of frosty pod rot (FPR, Moniliophthora roreri) and to a lesser extent, black pod disease (BPD, Phytophthora palmivora), and the necessity to renovate/rehabilitate the unproductive and susceptible plantations using improved varieties. Clones resistant to FPR and/or BPD were identified in the International Cacao Genebank (IC3) by using artificial inoculation techniques developed at CATIE. They were incorporated in a breeding strategy initiated at CATIE in the late 1990's to generate superior clones and hybrid families possessing disease resistance, high-yield and good quality. This effort has been supported by the World Cocoa Foundation, USDA-ARS, and CFC/Bioversity. The first outstanding clones were recently released for farmer observation and eventual use in six Central American countries through a regional cacao project (PCC), which is executed by CATIE and supported by NORAD (Norway) and farmer organizations. A comprehensive characterization/evaluation of the released clones was previously performed by using different agronomic, morphological, and phytopathological parameters. Self-and crosscompatibility were also determined. The results were complemented with a quality study supported by Guittard Chocolate Co. The establishment of 30 hectares of clonal gardens and 6 hectares of experimental field trials are part of the regional strategy in progress.

2025, OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information)

2025

s: Oral presentations What have we learnt from the Atlas and Virtual Museum projects?

2025, Polar Research

Aerial strip surveys of polar bears in the Barcnts Sca were performed by helicopter in wintcr 19x7. The number of bears within 100 m on each side of the helicopter was counted. A total of 263.6 km2 was survcycd and 21 bears were counted. Moat of the bcars wcrc found in thc southern part of the area. which indicates that the southwestern ice edge area in thc Barents Sca is a very important winter habitat for polar bears.

2025, Proceedings of the National Academy of Sciences

Human settlement of Oceania marked the culmination of a global colonization process that began when humans first left Africa at least 90,000 years ago. The precise origins and dispersal routes of the Austronesian peoples and the associated Lapita culture remain contentious, and numerous disparate models of dispersal (based primarily on linguistic, genetic, and archeological data) have been proposed. Here, through the use of mtDNA from 781 modern and ancient Sus specimens, we provide evidence for an early human-mediated translocation of the Sulawesi warty pig ( Sus celebensis ) to Flores and Timor and two later separate human-mediated dispersals of domestic pig ( Sus scrofa ) through Island Southeast Asia into Oceania. Of the later dispersal routes, one is unequivocally associated with the Neolithic (Lapita) and later Polynesian migrations and links modern and archeological Javan, Sumatran, Wallacean, and Oceanic pigs with mainland Southeast Asian S. scrofa . Archeological and geneti...

2025, Parasites & Vectors

BACKGROUND Birds have long been known as carriers of ticks, but data from the literature are lacking on their role as a reservoir in the epidemiology of certain tick-borne disease-causing agents. Therefore, the aim of this study was to evaluate the presence of three emerging, zoonotic tick-borne pathogens in blood samples and ticks of birds and to assess the impact of feeding location preference and migration distance of bird species on their tick infestation. METHODS Blood samples and ticks of birds were analysed with TaqMan real-time PCRs and conventional PCR followed by sequencing. RESULTS During the spring and autumn bird migrations, 128 blood samples and 140 ticks (Ixodes ricinus, Haemaphysalis concinna and a Hyalomma specimen) were collected from birds belonging to 16 species. The prevalence of tick infestation and the presence of tick species were related to the feeding and migration habits of avian hosts. Birds were shown to be bacteraemic with Rickettsia helvetica and Anaplasma phagocytophilum, but not with Candidatus Neoehrlichia mikurensis. The prevalence of rickettsiae was high (51.4%) in ticks, suggesting that some of them may have acquired their infection from their avian host. CONCLUSION Based on the present results birds are potential reservoirs of both I. ricinus transmitted zoonotic pathogens, R. helvetica and A. phagocytophilum, but their epidemiological role appears to be less important concerning the latter, at least in Central Europe.

2025, Journal of Fish Diseases

2025, Biometrics

We present a novel formulation of a mark-recapture-resight model that allows estimation of population size, stopover duration, and arrival and departure schedules at migration areas. Estimation is based on encounter histories of uniquely marked individuals and relative counts of marked and unmarked animals. We use a Bayesian analysis of a state-space formulation of the Jolly-Seber mark-recapture model, integrated with a binomial model for counts of unmarked animals, to derive estimates of population size and arrival and departure probabilities. We also provide a novel estimator for stopover duration that is derived from the latent state variable representing the interim between arrival and departure in the state-space model. We conduct a simulation study of field sampling protocols to understand the impact of superpopulation size, proportion marked, and number of animals sampled on bias and precision of estimates. Simulation results indicate that relative bias of estimates of the pr...