Genetics and analysis of quantitative traits

A DNA test to sex most birds.

Long distance migration has evolved in many organisms moving through different media and using various modes of locomotion and transport. Migration continues to evolve or become suppressed as shown by ongoing dynamic and rapid changes of migration patterns. This great evolutionary flexibility may seem surprising for such a complex attribute as migration. Even if migration in most cases has evolved basically as a strategy to maximise fitness in a seasonal environment, its occurrence and extent depend on a multitude of factors. We give a brief overview of different factors (e.g. physical, geographical, historical, ecological) likely to facilitate and/or constrain the evolution of long distance migration and discuss how they are likely to affect migration. The basic driving forces for migration are ecological and biogeographic factors like seasonality, spatiotemporal distributions of resources, habitats, predation and competition. The benefit of increased resource availability will be balanced by costs associated with the migratory process in terms of time (incl. losses of prior occupancy advantages), energy and mortality (incl. increased exposure to parasites). Furthermore, migration requires genetic instructions (allowing substantial room for learning in some of the traits) about timing, duration and distance of migration as well as about behavioural and physiological adaptations (fuelling, organ flexibility, locomotion, use of environmental transport etc) and control of orientation and navigation. To what degree these costs and requirements put constraints on migration often depends on body size according to different scaling relationships. From this expos it is clear that research on migration warrants a multitude of techniques and approaches for a complete as possible understanding of a very complex evolutionary syndrome. In addition, we also present examples of migratory distances in a variety of taxons. In recent years new techniques, especially satellite radio telemetry, provide new information of unprecedented accuracy about journeys of individual animals, allowing re-evaluation of migration, locomotion and navigation theories. (Less)

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Long-distance migration: evolution and determinants

Handbook of the Birds of Europe, the Middle East and North Africa: the Birds of the Western Palaearctic. Volume 2. Hawks to Bustards

Actions of glucocorticoids at a seasonal baseline as compared to stress-related levels in the regulation of periodic life processes.

Energy management for endurance flight critically determines the ecological options in the life history of migrant birds. Apart from the amount of energy stores, the types of fuel used and metabolic constraints determine endurance performance in long-distance migrants. The three main types of fuel (lipids, glycogen, protein) are evaluated regarding (a) costs of transport and maintenance, (b) supply to the muscles during flight, (c) adverse effects during, and (d) after, flight, and (e) refuelling. Lipids are the best fuel type with respect to three of these five criteria, but pose problems regarding the supply from adipose tissues to the muscles and regarding oxidation. Nevertheless, birds can maximize the contribution of energy derived from lipids as a proportion of the total energy expenditure to about 95% during migratory endurance flight. Mechanisms to do so may include enhancing fatty acid transport to the flight muscles, increasing initial fat stores and increasing aerobic capacity. A very low relative contribution of energy derived from protein (RPC) is attained by migrating birds (around 5%), similar to that of long-term fasting birds. RPC values of fasting birds depend on initial fat content and are lower than in fasting mammals. This suggests that in fasting birds the absolute amount of protein catabolism is roughly proportional to metabolic rate. Mechanisms to increase the relative contribution of energy derived from fat are costly. Hence, they are expected to modify the power curve relating energy expenditure to flight speed and predictions derived from it. It is also expected that migrants flying short non-stop distances or risking dehydration will not maximize lipid utilization to the same extent as birds flying long distances non-stop. Hence, the optimal amount and proportions of fat and protein stored and functional organ sizes are expected to depend on the migration strategy, particularly on the duration of non-stop flights and the risk of dehydration.

Fuel supply and metabolic constraints in migrating birds

-Change in body mass is an important measurement in many studies addressing changes in energy stores or condition. Usually, change in body mass is measured in birds caught twice, but this has a number of drawbacks (e.g. low number of retraps, retraps not representative of all first captures, adverse effects of first capture on body-mass development). Therefore, we investigated whether plasma metabolites correlate with body-mass change, and which metabolites could be used to predict body-mass change in birds caught once. In an experiment, 20 Garden Warblers (Sylvia borin) were given different amounts of food to induce stable, increasing, and decreasing body masses. Most of the eight plasma metabolites we examined were significantly correlated with the change in body mass between early morning and midday, the time of blood sampling, but not with body mass or various measures of activity. Metabolites that are known to characterize resorption were elevated in birds gaining body mass and metabolites characteristic of fasting were elevated in birds losing body mass. Triglycerides and ,B-hydroxy-butyrate together explained 61% of the variation in body-mass change (triglycerides alone 44% and ,3-hydroxy-butyrate alone 51%). These metabolites may be used to predict body-mass change in birds caught once, provided that the reliability and sensitivity of this method are checked in field tests. Received 27 September 1993, accepted 30 January 1994. BIRDS MAY FACE DEFICITS in their energy balance during the nonactive period of the day, during periods of several days, or even over a series of weeks. They usually build up energy stores in anticipation of such periods and as an adaptive compromise to different selective pressures (e.g. Lima 1986, Lehikoinen 1987, Moreno 1989, Ekman and Hake 1990, Rogers and Smith 1993). This results in fluctuating energy stores between foraging and nonforaging periods (usually day and night) superimposed on longer periods of net energy storage and net energy expenditure (King 1972). For instance, cold and short winter days, bad weather, incubation, feeding young, and migration may all be associated with decreasing energy stores and preceded by energy storage. Body mass is a crude but widely used estimate of energy stores because it is easy and harmless to measure. If corrected for size, body mass may be used as an indication of condition (e.g. Blem 1990). Changes in body mass may give a fairly accurate picture of the fluctuations in energy stores (e.g. Rogers and Rogers 1990). The measurement of changes in body mass of free-living birds is important in a variety of contexts. For instance, it may allow the assessment of the effects of food availability on energy storage in different habitats, under different weather conditions, and under different degrees of competition or predation (e.g. Bibby et al. 1976, Bibby and Green 1983, Buchanan et al. 1985, Lima 1985, Lindstrom 1990, Moore and Yong 1991). Body-mass changes may indicate periods of constraints and periods of adaptive mass variations during the annual cycle (Moreno 1989). Evaluation of body-mass changes may allow study of the pattern and environmental influences of energy storage during stopovers by migrants (e.g. Bibby et al. 1976, Mehlum 1983a, b, Biebach 1985, Biebach et al. 1986, Alerstam and Lindstrom 1990). In free-living birds, changes in body mass generally are measured in birds caught at least twice, usually at the same place. This, however, has a number of drawbacks: (1) changes in body mass are measured only in the subsample of retraps and this may reduce the sample size drastically, especially when trap shyness is a factor; (2) a certain group of birds may not be recaught and, thus, the sample of retraps may not be representative (e.g. Bibby et al. 1976, Biebach et al. 1986, Veiga 1986, Winker et al. 1992); and (3) first capture may have an adverse

https://www.jstor.org/stable/info/4088821

Plasma Metabolite Levels Predict Individual Body-Mass Changes in a Small Long-Distance Migrant, the Garden Warbler

1. Human outdoor recreational activities are increasing and have a significant impact on wildlife. There are few methods suitable for investigating the response of rare and endangered species to human recreational activities, although the impact can be assessed at various scales by measuring both physiological and behavioural responses to disturbance.
2. Capercaillie Tetrao urogallus are suffering strong population declines throughout central Europe. We examined the effects of ski tourism on capercaillie habitat use and adrenocortical activity, measured non-invasively in droppings.
3. During three winters, 2003–06, we radio-tracked 13 capercaillie. In the southern Black Forest in Germany, we sampled 396 droppings of these and additional individuals before and after the start of the ski season. We tested whether the intensity of human winter recreational activities affected home range location and habitat use, and we identified those factors influencing the concentration of corticosterone metabolites (CM) in droppings.
4. Capercaillie used habitats subject to ski tourism. Although the latter did not affect home range location, capercaillie preferred undisturbed forests within their home ranges and avoided areas with high recreation intensity in the ski season. Faecal CM levels of individuals in areas with low recreation intensity were significantly lower than those in areas with moderate or high recreation intensity during the entire study period.
5. We conclude that ski tourism affects both habitat use and endocrine status in capercaillie, with potential negative consequences on body condition and overall fitness.
6. Synthesis and applications.
This study demonstrates the relevance of studying wildlife responses at various temporal and spatial scales, and the value of using multiple methods applied to the same individuals to monitor the impact of human recreational activities on a free-ranging species. In order to protect capercaillie populations, we recommend that managers keep forests inhabited by capercaillie free from tourism infrastructure and retain undisturbed forest patches within skiing areas.

Ski tourism affects habitat use and evokes a physiological stress response in capercaillie Tetrao urogallus: a new methodological approach

The use of small Unmanned Aircraft Systems (UAS; also known as "drones") for professional and personal-leisure use is increasing enormously. UAS operate at low altitudes (<500 m) and in any terrain, thus they are susceptible to interact with local fauna, generating a new type of anthropogenic disturbance that has not been systematically evaluated. To address this gap, we performed a review of the existent literature about animals' responses to UAS flights and conducted a pooled analysis of the data to determine the probability and intensity of the disturbance, and to identify the factors influencing animals' reactions towards the small aircraft. We found that wildlife reactions depended on both the UAS attributes (flight pattern, engine type and size of aircraft) and the characteristics of animals themselves (type of animal, life-history stage and level of aggregation). Target-oriented flight patterns, larger UAS sizes, and fuel-powered (noisier) engines evoked the strongest reactions in wildlife. Animals during the non-breeding period and in large groups were more likely to show behavioral reactions to UAS, and birds are more prone to react than other taxa. We discuss the implications of these results in the context of wildlife disturbance and suggest guidelines for conservationists, users and manufacturers to minimize the impact of UAS. In addition, we propose that the legal framework needs to be adapted so that appropriate actions can be undertaken when wildlife is negatively affected by these emergent practices.

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Unmanned aircraft systems as a new source of disturbance for wildlife: A systematic review

Stress generated by humans on wildlife by continuous development of outdoor recreational activities is of increasing concern for biodiversity conservation. Human disturbance often adds to other negative impact factors affecting the dynamics of vulnerable populations. It is not known to which extent the rapidly spreading free-riding snow sports actually elicit detrimental stress (allostatic overload) upon wildlife, nor what the potential associated fitness and survival costs are. Using a non-invasive technique, we evaluated the physiological stress response induced by free-riding snow sports on a declining bird species of Alpine ecosystems. The results of a field experiment in which radiomonitored black grouse (Tetrao tetrix) were actively flushed from their snow burrows once a day during four consecutive days showed an increase in the concentration of faecal stress hormone (corticosterone) metabolites after disturbance. A large-scale comparative analysis across the southwestern Swiss Alps indicated that birds had higher levels of these metabolites in human-disturbed versus undisturbed habitats. Disturbance by snow sport free-riders appears to elevate stress, which potentially represents a new serious threat for wildlife. The fitness and survival costs of allostatic adjustments have yet to be estimated.

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Susanne Jenni-Eiermann

Papers

Fuel supply and metabolic constraints in migrating birds

Plasma Metabolite Levels Predict Individual Body-Mass Changes in a Small Long-Distance Migrant, the Garden Warbler

Ski tourism affects habitat use and evokes a physiological stress response in capercaillie Tetrao urogallus: a new methodological approach

Unmanned aircraft systems as a new source of disturbance for wildlife: A systematic review

Spreading free-riding snow sports represent a novel serious threat for wildlife