Tomáš Kušta

Dogs are sensitive to small variations of the Earth’s magnetic field

IntroductionSeveral mammalian species spontaneously align their body axis with respect to the Earth’s magnetic field (MF) lines in diverse behavioral contexts. Magnetic alignment is a suitable paradigm to scan for the occurrence of magnetosensitivity across animal taxa with the heuristic potential to contribute to the understanding of the mechanism of magnetoreception and identify further functions of magnetosensation apart from navigation. With this in mind we searched for signs of magnetic alignment in dogs. We measured the direction of the body axis in 70 dogs of 37 breeds during defecation (1,893 observations) and urination (5,582 observations) over a two-year period. After complete sampling, we sorted the data according to the geomagnetic conditions prevailing during the respective sampling periods. Relative declination and intensity changes of the MF during the respective dog walks were calculated from daily magnetograms. Directional preferences of dogs under different MF conditions were analyzed and tested by means of circular statistics.ResultsDogs preferred to excrete with the body being aligned along the North–South axis under calm MF conditions. This directional behavior was abolished under unstable MF. The best predictor of the behavioral switch was the rate of change in declination, i.e., polar orientation of the MF.ConclusionsIt is for the first time that (a) magnetic sensitivity was proved in dogs, (b) a measurable, predictable behavioral reaction upon natural MF fluctuations could be unambiguously proven in a mammal, and (c) high sensitivity to small changes in polarity, rather than in intensity, of MF was identified as biologically meaningful. Our findings open new horizons in magnetoreception research. Since the MF is calm in only about 20% of the daylight period, our findings might provide an explanation why many magnetoreception experiments were hardly replicable and why directional values of records in diverse observations are frequently compromised by scatter.

Magnetic Alignment in Carps: Evidence from the Czech Christmas Fish Market

While magnetoreception in birds has been studied intensively, the literature on magnetoreception in bony fish, and particularly in non-migratory fish, is quite scarce. We examined alignment of common carps (Cyprinus carpio) at traditional Christmas sale in the Czech Republic. The sample comprised measurements of the directional bearings in 14,537 individual fish, distributed among 80 large circular plastic tubs, at 25 localities in the Czech Republic, during 817 sampling sessions, on seven subsequent days in December 2011. We found that carps displayed a statistically highly significant spontaneous preference to align their bodies along the North-South axis. In the absence of any other common orientation cues which could explain this directional preference, we attribute the alignment of the fish to the geomagnetic field lines. It is apparent that the display of magnetic alignment is a simple experimental paradigm of great heuristic potential.

Directional compass preference for landing in water birds

IntroductionLanding flight in birds is demanding on visual control of velocity, distance to target, and slope of descent. Birds flying in flocks must also keep a common course of landing in order to avoid collisions. Whereas the wind direction may provide a cue for landing, the nature of the landing direction indicator under windless conditions has been unknown. We recorded and analysed landing directions of 3,338 flocks in 14 species of water birds in eight countries.ResultsWe show that the preferred landing direction, independently of the direction from which the birds have arrived, is along the north-south axis. We analysed the effect of the time of the year, time of the day (and thus sun position), weather (sunny versus overcast), light breeze, locality, latitude, and magnetic declination in 2,431 flocks of mallards (Anas platyrhynchos) and found no systematic effect of these factors upon the preferred direction of landing. We found that magnetic North was a better predictor for landing direction than geographic North.ConclusionsIn absence of any other common denominator determining the landing direction, the alignment with the magnetic field lines seems to be the most plausible if not the only explanation for the directional landing preference under windless and overcast conditions and we suggest that the magnetic field thus provides a landing direction indicator.

Trophic Discrimination Factors of Stable Carbon and Nitrogen Isotopes in Hair of Corn Fed Wild Boar

Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species- specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were –2.3 ‰ and +3.5 ‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d-1. Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types.

Effect of habitat and game management practices on ring-necked pheasant harvest in the Czech Republic

The ring-necked pheasant (Phasianus colchicus L.) is one of the most popular small game species both numerically and economically. Pheasant populations are commonly managed in the Czech Republic in order to maximize their harvest. Game managers need to be aware of the possible effects of different management tools on wild pheasant populations. We used data from 38 hunting grounds collected over an 8-year period (2004–2011) and generalized linear mixed effects models (GLMMs) to assess whether pheasant harvest was related to the habitat characteristics and game management practices (release of hand-reared individuals and predator control) in the Czech Republic. The proportion of grasslands, idle lands (spontaneously set-aside lands), and organically farmed lands (i.e., with limited use of industrially made fertilizers and pesticides) and the density of watercourses were positively related to the pheasant harvest. The proportion of forests and road density showed a negative relationship with the pheasant harvest. An important effect of year on the pheasant harvest was also found. In terms of game management practices, predator control intensity (i.e., foxes, martens, corvids) was positively related to the pheasant harvest. The release of hand-reared individuals was not included in the final GLMMs. Our study suggests that the best long-term strategy to reinforce the wild population of ring-necked pheasants would be to concentrate on habitat improvement through the implementation of set-aside management, maintaining the right percentage of shrubby and grass vegetation, to continue with targeted predator control, and to reduce the costly practice of releasing of hand-reared individuals.

Railway Ecology—Experiences and Examples in the Czech Republic

The range of direct and indirect effects of railway transport on animals, plants, ecological processes and the actual ecosystems vary considerably. Railway transport operations and infrastructure building lead to environmental pollution, loss or conversion of habitats, landscape fragmentation and, last but not least, to animal mortality caused by collisions with passing trains. The impact of railways is determined by the nature of railway infrastructure, which is not as significant in the Czech Republic as road infrastructure, yet it is one of the densest in Europe. An important feature is relatively low electrification (about 33% of the lines) and the length of multi-track lines (about 20%). In the coming years, we can expect massive investments in revitalization, optimization and modernization of the railways in the Czech Republic, and eventually their electrification. To connect the crucial trans-European lines and all regions it will be necessary to complete the basic network of high-speed railways. Based on these facts we can say that the significance of railway ecology in the Czech Republic will grow with the amount of investment activities implemented in the railway network. In the past, similar development took place with road infrastructure, and therefore there is an opportunity to learn from it. To mitigate the direct effects of railways on wildlife, on the basis of previous experience in the Czech Republic we recommend working primarily with management measures. These are both in terms of wildlife management and the management of habitats in the area of transport infrastructure.

Evaluation of winter food quality and its variability for red deer in forest environment: overwintering enclosures vs. free-ranging areas

Abstract Populations of European ungulates have grown substantially over recent decades, resulting in considerable environmental and socio-economic impacts. Availability and quality of natural and supplemental food sources are among the main factors driving their population dynamics. Detailed knowledge of food quality of management-targeted species is therefore of primary importance for their successful management. The main aim of this study was to evaluate winter food quality and its variability for an important ungulate species in the Czech Republic - i.e. red deer, using faecal indices (faecal nitrogen, faecal acid detergent fibre, faecal neutral detergent fibre) and near infrared reflectance spectroscopy. We compared food quality for red deer and its possible differences between overwintering enclosures (i.e. fenced areas where red deer spend harsh winter conditions) and neighbouring unfenced free-ranging areas within two study areas. The results obtained showed that winter food quality and its variability for red deer are of different quality and variability in the overwintering enclosure and neighbouring free-ranging area. The observed differences in concentrations and amounts of variation of faecal indices are most probably related to animal densities at individual study areas. Wildlife managers should therefore keep animals in overwintering enclosures at moderate densities and to provide high quality forage to all individuals in order to balance nutrition of both the individuals inside and outside the enclosures. Nevertheless, further studies are needed in order to provide deeper knowledge on red deer food quality and its variability in space and time.

Age Structure and Reproduction Rates of the Ring-Necked Pheasant (Phasianus colchicus L.) Population in Agricultural Landscape (Czech Republic)

ABSTRACT: Detailed knowledge of demographic parameters (such as age structure and reproduction rates) is crucial for guiding conservation and management decisions regarding wildlife populations. Such parameters of wild ring-necked pheasant populations in the current agricultural landscape remain very poorly described. We researched age structure and reproduction rates of predominantly wild populations of the ring-necked pheasant (Phasianus colchicus L.) across the intensively managed agricultural landscape of the Czech Republic. The study area is influenced only marginally by hand-reared pheasants (i.e. as shown by comparison of the average number of released individuals in the study area: 0.3 ♂/yr/1km2 and 0.9 ♀/yr/1km2 and average number of released individuals and harvested in the study area: 8.6 ♂/yr/1km2) and there is a long-term huntable pheasant population. To determine the age of individuals, we used proximal primary feather shaft diameters of 1487 feather samples from males hunted between 2009 and 2011. Moreover, we evaluated the age structure of females as well as both sexes together based on the sex ratio and annual game census. We found a relatively high proportion of adults in the population in comparison with other studies. However, the number of adults decreased throughout the years: 2009 (♂ 44.7%; ♀ 69.5%; ♂♀ 60.7%), 2010 (♂ 35.2%; ♀ 61.3%; ♂♀ 51.5%), 2011 (♂ 29.8%; ♀ 57.4%; ♂♀ 47.0%). The decrease of adults went hand in hand with increase of juveniles and reproduction rates of the study population: 2009 (♂ 124%; ♀ 44%; ♂♀ 65%), 2010 (♂ 184%; ♀ 63%; ♂♀ 94%), 2011 (♂ 236%; ♀ 74%; ♂♀ 113%). Only males were hunted in the study area so we determined higher proportions of females in population for all years. This is the main reason why the reproduction rate of females was lower in percentage expression. Generally, our results showed lower productivity of pheasants in the Czech agricultural landscape in comparison with earlier published studies conducted in the US and UK. However, these studies were published many years ago and thus do not reflect the actual environmental conditions and changes which took place recently (i.e. agricultural intensification).

Daily activity rhythm and habitat use of the semi-free European bison herd during the growing season / Denní aktivita a využití prostředí zubrem evropským (Bison bonasus) během vegetační sezóny

Abstract The European bison (Bison bonasus) became extinct in the wild in the 20th century. Due to successful reintroductions of captive individuals, the free-ranging bison population has been steadily increasing. However, the population consists of small and isolated herds whose survival depends on creating larger and connected populations. Detailed knowledge of movement and habitat use in human-dominated landscape is essential for further successful reintroductions of the European bison. Therefore, we studied daily activity and habitat use of the semi-free European bison herd in the hunting enclosure of Židlov from April to September 2014. The lead cow of the herd was fitted with a GPS collar equipped with GSM module. The average home range size of the herd was 29.5 km2 and the average daily utilisation area was 0.5 km2. Forested habitats were preferred during the day (Rayleigh test: Z = 107.31; p < 0. 0001) whereas idle lands (i.e. former shooting ranges now dominated by a mixture of pioneer tree species, hawthorn and grasslands) during the night (Rayleigh test: Z = 214.451; p < 0. 0001). The bison herd did not show any clear preference for a particular forest type (i.e. coniferous, deciduous, different age classes). Additional knowledge on year-long patterns of movement and habitat use is needed to ensure the success of reintroduction programmes Abstrakt Zubr evropský (Bison bonasus) vyhynul ve volné přírodě na začátku 20-tého století. Následně byl ze zajetí reintrodukován do několika oblastí střední Evropy a od té doby jeho početnost roste. Nicméně jeho současný výskyt je koncentrován pouze do malých populací a jejich další přirozený vývoj je závislý na vytvoření konceptu vzájemného propojení. Pro vytvoření a realizaci tohoto konceptu je kladen důraz na znalost prostorové aktivity zubra a jeho preference prostředí. Tyto znalosti budou esenciální zejména v oblastech uvažované reintrodukce v typech krajiny intenzivně využívaných lidskou činností. Naše studie se proto zabývá denní aktivitou a využitím území reintrodukovaného stáda zubrů v oboře Židlov ve vegetačním období (duben - září 2014). Byla sledována hlavní samice, označena GPS obojkem s GSM modulem. Domovský okrsek stáda během celého sledovaného období byl 29,5 km2 a velikost průměrného denního využívaného území bylo 0,5 km2. Statisticky signifikantní rozdíl byl ve využívání různých typů porostů, kdy během dne zubři využívali lesní prostředí (Rayleigh test: Z = 107.31; p < 0. 0001) a během noci naopak otevřené porosity (Rayleigh test: Z = 214.451; p < 0. 0001). Zubří stádo nevykazovalo výrazné preference pro jednotlivé typy porostů (jehličnaté, listnaté, věkové třídy). Další studie zabývající se prostorovým chováním zubra a jeho variability během celého roku jsou pro další úspěšné reintrodukce tohoto druhu nezbytné