West Indian Manatees Use Partial Migration to Expand Their Geographic Range Into the Northern Gulf of Mexico

Partial migration provides a mechanism for species to shift their geographic ranges into new, environmentally favorable regions but has been poorly studied as a means to alleviate effects of climate change. Populations at the edge of their geographic range are ideal to investigate how migratory behaviors may enable range expansion as adjacent areas become more climatically favorable. We determined the contribution of partial migration to the range expansion of West Indian manatees (Trichechus manatus) using GPS data from tagged individuals that migrated between the northern Gulf of Mexico (nGoM) and primary habitat in peninsular Florida. Most of these manatees migrated to the nGoM annually and exhibited high site fidelity among years. Many individuals spent cumulatively more time in the nGoM than in peninsular Florida, indicating the nGoM is a regular part of their geographic range, and they returned to peninsular Florida to meet temperature-related physiological needs for survival. Autumn migrations most frequently terminated at Crystal River, Florida, and manatees that commenced migration late in the season stopped less frequently and had more directed movements. Spring migrations most frequently terminated at Mobile Bay, Alabama, and several manatees quickly and directly migrated from Florida to nGoM stopover sites. Migrations ranged from 10 to 133 days in length, and variation in duration was primarily driven by use of stopover sites and directedness of travel. These data confirm partial migration as an important component of manatee migratory behavior that has already enabled range shifts for manatees on the U.S.A. Gulf of Mexico coast and has potential to facilitate future responses to climate change. As the most common type of migration across the animal kingdom, partial migration may provide a global mechanism for a diverse variety of species to resist the range limiting effects of climate change.

Seasonal migratory patterns of Pacific cod (Gadus macrocephalus) in the Aleutian Islands

Background Pacific cod (Gadus macrocephalus) is an ecologically important species that supports a valuable commercial fishery throughout Alaska waters. Although its life history includes seasonal movement for spawning and feeding, little is known about its movement ecology. Here, we present results from the first study to use pop-up satellite archival tags (PSATs) to track the within-year movements of Pacific cod to understand their potential seasonal movement patterns within the Aleutian Islands. This study was part of a cooperative research project; tagging was conducted onboard commercial vessels during the winter fishing season while Pacific cod were aggregated to spawn in the central Aleutian Islands. Results Of the 36 PSATs deployed, we were able to obtain movement data from 13 Pacific cod that were at liberty between 60 and 360 days. We determined that three tagged Pacific cod were predated on by marine mammals and three were recaptured by the commercial fishery. Geolocation models were produced for four migrating individuals. Eight Pacific cod moved to a productive foraging ground near Seguam Island located 64 to 344 km from their release site and presumed spawning ground within a few weeks of their release. These movements indicate that some Pacific cod in the Aleutian Islands undergo seasonal migration. Three Pacific cod remained near their release locations (within 50 km) for more than 75 days suggesting the existence of partial migration in the population. Two Pacific cod undertook larger movements (378 and 394 km) during which they swam over deep passes and crossed several management boundaries highlighting the potential connectedness of Pacific cod throughout the Aleutian Islands. Conclusions This study provided important initial insights into the seasonal movement patterns of Pacific cod in the Aleutian Islands. Most tracked Pacific cod (77%) undertook migrations in the middle of March (64–394 km) from their winter spawning areas to summer foraging areas, but a few individuals remained in their capture location suggesting a partial migration strategy. Their ability to cross deep passes that were previously seen as potential barriers to movement has expanded our understanding of population connectivity.

Drivers and Consequences of Partial Migration in an Alpine Bird Species

1. Partial migration, where a portion of the population migrates between winter and summer (breeding) areas and the rest remain year-round resident, is a common phenomenon across several taxonomic groups. Yet, although several hypotheses have been put forward to explain why some individuals migrate while others stay resident – as well as the fitness consequences of the different strategies – the drivers and consequences of the decision to migrate or not are poorly understood. 2. We used data from radio-tagged female (n=73) willow ptarmigan Lagopus lagopus in an alpine study area in Central Norway to test if i) the decision to migrate was dependent on individual state variables (age and body size), ii) individuals repeated migratory behaviour between seasons, and iii) the choice of migratory strategy was related to nesting performance.3. Partially supporting our prediction that migratory strategy depends on individual state, we found that juvenile birds with small body sizes were more likely to migrate whereas large juveniles stayed resident. For adult females, we found no relationship between migratory strategy and body weight. We found strong evidence for high individual repeatability of migratory strategy between seasons. Migratory strategy did not explain variation in nesting performance among individuals, suggesting no direct influence of the chosen strategy on nesting success. 4. Our results indicate that partial migration in willow ptarmigan is determined by juvenile body weight, and that migratory behaviour becomes a part of the individual life history as a fixed strategy. Nesting success was not affected by migratory strategy in our study population, but future studies should assess other traits to further test potential fitness consequences.

TOWARDS THE HISTORY AND POPULATION COMPOSITION OF THE HISTORICAL AND GEOGRAPHICAL REGIONS GUMBET, ANDI AND ALATAVIA

В публикуемой статье рассматривается вопрос взаимного проникновения и исторических контактов населения приграничных областей Чечни и Дагестана – Гумбета, Анди и Салатавии. В исследовании приводится ряд документальных, нарративных (рукописи) и этнографических источников, позволяющих более тщательно взглянуть на вопрос этногенеза обществ указанных историко-географических областей. Кроме того, выявляется закономерность, согласно которой в пространстве между реками Аргун и Кара-Койсу (приток Сулака) распространен целый ряд топонимов и общин, чьи названия обнаруживают основу гун / хун / хон, что, как это видно из источников, увязывается с кавказскими гуннами, или хонами. Также в контексте затронутой проблематики указывается на движение этнических масс с запада (Нашха, Шубут и т.д.) и юга (Ичкерия) в область Анди и далее – в Салатавию через область Гумбет. Проводится попытка определить время возникновения аула Анди, а также выявить общества и личности, принявшие участие в основании села и выступившие в качестве этнического субстрата, по крайней мере, северной группы андийских поселений и тохумов. Отмечается роль Унсура (Энсура), его братьев Баши и Араша, а также владетелей Ануша и Харчи-хана, принявших первого в андийской котловине после его исхода «из селения Шубут» вследствие произошедшего кровопролития. На основании разностороннего анализа, с привлечением архивных материалов авторами указывается на участие общин Дишний, Гуной, Вашандарой, Харачой, Беной, Зумсой и др. в качестве субстрата при формировании североандийских поселений, а также их частичной миграции в Салатавию. The published article examines the issue of mutual penetration and historical contacts of the population of the border regions of Chechnya and Dagestan - Gumbet, Andi and Salatavia. The study provides a number of documentary, narrative (manuscripts) and ethnographic sources that allow a more thorough look at the issue of the ethnogenesis of societies in these historical and geographical areas. In addition, a pattern is revealed according to which a number of toponyms and communities are widespread in the space between the Argun and Kara-Koisu rivers (a tributary of the Sulak), whose names reveal the basis of the Gun / Hun / Khon, which, as can be seen from the sources, is associated with the Caucasian Huns , or hons. Also, in the context of the problems touched upon, the movement of ethnic masses from the west (Nashkha, Shubut, etc.) and south (Ichkeria) to the Andi region and further to Salatavia through the Gumbet region is indicated. An attempt is made to determine the time of the emergence of the Andi aul, as well as to identify the societies and individuals who took part in the founding of the village and acted as an ethnic substratum, at least, of the northern group of Andean settlements and Tohums. The role of Unsur (Ensur), his brothers Bashi and Arash, as well as the rulers of Anush and Kharchi-khan, who took the first in the Andean basin after his exodus “from the village of Shubut” due to the bloodshed, is noted. Based on a multifaceted analysis, with the involvement of archival materials, the authors point out the participation of the communities of Dishny, Guna, Washandara, Kharacha, Benoy, Zumsoy, etc. as a substrate in the formation of North Indian settlements, as well as their partial migration to Salatavia.

Energetic state and the continuum of migratory tactics in brown trout (Salmo trutta)

Alternative migratory tactics, like partial migration, are common in many taxa. The proximate and ultimate drivers underpinning these strategies are unclear, though factors like condition and energetic status have been posited as important predictors. We sampled and PIT tagged 1882 wild brown trout prior to the first so-called decision window, and explored the links between migratory tactics (residency, autumn or spring migration) and body metrics (length and condition), lipids (triglycerides and cholesterol), and sex, in 150 randomly selected individuals. We found that more females adopted the autumn and spring migration tactic than males, while more males adopted the residency tactic than females, likely reflecting sex-biased benefits in anadromy. We also found that autumn migrants were in poorer condition prior to the presumed first decision window than spring migrants and residents. Lastly, we found that both condition and cholesterol were positively correlated to the timing of migration, such that individuals in poorer condition and/or with lower cholesterol migrated earlier. Collectively, these results suggest that energy depletion is an important factor in determining migratory strategy, including timing.

Differential migration in Pacific salmon and trout: Patterns and hypotheses

Migrations affect the population dynamics, life history, evolution, and connections of animals to natural ecosystems and humans. Many species and populations display partial migration (some individuals migrate and some do not), and differential migration (migration distance varies). Partial migration is widely distributed in fishes but the term differential migration is much less commonly applied, despite the occurrence of this phenomenon. This paper briefly reviews the extent of differential migration in Pacific salmon and trout (genus Oncorhynchus), a very extensively studied group. Three hypotheses are presented to explain the patterns among species: 1) phylogenetic relationships, 2) the prevalence of partial migration (i.e., variation in anadromy), and 3) life history patterns (iteroparous or semelparous, and duration spent feeding at sea prior to maturation). Each hypothesis has some support but none is consistent with all patterns. The prevalence of differential migration, ranging from essentially non-existent to common within a species, reflects phylogeny and life history, interacting with the geographic features of the region where juvenile salmon enter the ocean. Notwithstanding the uncertain evolution of this behavior, it has very clear implications for salmon conservation, as it strongly affects exposure to predators, patterns of fishery exploitation and also uptake of toxic contaminants.

Carryover effects of long-distance avian migration are weaker than effects of breeding environment in a partially migratory bird

Migration may expose individuals to a wide range of increasing anthropogenic threats. In addition to direct mortality effects, this exposure may influence post-migratory reproductive fitness. Partial migration—where a population comprises migrants and residents—represents a powerful opportunity to explore carryover effects of migration. Studies of partial migration in birds typically examine short-distance systems; here we studied an unusual system where residents breed in mixed colonies alongside long-distance trans-Saharan migrants (lesser kestrels (Falco naumanni) in Spain). Combining geolocator data, stable isotope analysis and resighting data, we examined the effects of this stark difference in migratory strategy on body condition, breeding phenology and breeding success. We monitored four colonies in two regions of southern Spain for five consecutive years (2014–2018), yielding 1962 captures, determining migratory strategy for 141 adult bird-years. Despite a 3000-km difference in distance travelled, we find no effect of strategy on breeding parameters. We find weak evidence for a short-term negative carryover effect of migration on body condition, but this was only apparent in the breeding region with lower primary productivity. Our results indicate that carryover effects of even highly divergent migratory strategies may be minimal relative to effects of conditions experienced on breeding grounds.