Vplivi zgradbe habitata na telesno maso jelenjadi (Cervus elaphus)

In most mammalian species, body mass is one of the key factors affecting an individual\u27s fitness. It is therefore important to know the causes of its variability. The present paper analyses the influences of habitat structure and other environmental factors on body mass in red deer. The research is based on data sets concerning 3,920 culled red deer from the entire Slovenia, which are geo-referenced within a kilometer spatial accuracy, and on 28 spatially explicit raster layers of population density, habitat structure variables (e.g. topography, land use, forest structure, roads) and other environmental variables (e.g. air temperature, precipitation, supplementary feeding). After controlling for sex and age of the individual and its date of culling, body weight significantly differs between population areas, most likely as a result of genotype differences and genotype impact on the phenotype, and is also negatively dependent upon population density and the percentage of conifers and positively dependent upon annual mean air temperature and forest/meadow edge density. The stated environmental factors probably influence the achieved energy balance and, therefore, the body mass of red deer by conditioning the quantity and quality of food and energy expenditure of deer.Telesna masa je pri večini vrst sesalcev eden najpomembnejših faktorjev, ki vpliva na vitalnost osebka. Zato je pomembno poznati vzroke njene variabilnosti. V raziskavi smo celostno preučili vplive okoljskih dejavnikov na telesno maso jelenjadi (Cervus elaphus). Raziskava temelji na podatkih o 3.920 uplenjenih osebkih jelenjadi iz vse Slovenije, ki so georeferencirani s kilometrsko natančnostjo, in na 28 prostorsko-eksplicitnih rastrskih GIS-plasteh, ki podajajo populacijsko gostoto, zgradbo prostora (npr. topografija, raba tal, vegetacija, ceste) ter vrednosti drugih okoljskih spremenljivk (npr. temperatura zraka, padavine, dopolnilno krmljenje). Telesnamasa se po kontroliranju vplivov spola in starosti osebka ter datuma njegovega odvzema značilno razlikuje med populacijskimi območji, kar je verjetno posledica vplivov genotipa na fenotippoleg tega je negativno odvisna od populacijske gostote in deleža iglavcev ter pozitivno od povprečne celoletne temperature zraka in gostote gozdnega roba. Naštete okoljske spremenljivke verjetno vplivajo na doseženo energijsko bilanco in torej tudi na telesno maso jelenjadi s pogojevanjem količine in kakovosti hrane ter porabe energije

Vplivi dnevne, nočne in 24-urne sheme snemanja lokacij na ocene velikosti in zgradbe individualnih območij aktivnosti na primeru jelenjadi (Cervus elaphus)v Sloveniji

Most of the previous research on the mammals\u27 home range (HR) is based on diurnal sampling, while the results are often implicitly considered as representative for an entire 24-h period. However, there is a growing body of research on populations, whose habitat selection changes circadianly, which leads to the hypothesis that HR patterns may vary at different periods of the day. This study used 24-h data from 15 red deer equipped with GPS collars to explore differences in the size and composition of their HRs, estimated on diurnal, nocturnal and 24-h samplings. The differences in composition were shown on the forest/non-forest variable. We established that nocturnal, and inparticular the 24-h HRs, largely overlapped with the diurnal HRs (64% and 76%, respectively) and that parts of the HRs that are used exclusively nocturnally are contiguous or adjacent to diurnal HRs. The differences in HR sizes were significant only between diurnal and 24-h HRs. However, the HR composition varied substantially: the average proportion of non-forest areas was 15% in diurnal, 26% in 24-h and 31% in nocturnal HRs. This study demonstrated that with diurnal sampling it is impossible to assess accurately the size and composition of 24-h HRs of red deer in Slovenia. There are several indices that the same is true of several other populations/species. It is therefore important to be aware that HR patterns estimated on the basis of diurnal sampling may be incomplete or even wrong if generalised across the 24-h period.Večina raziskav območij aktivnosti (v nadaljevanju HR) sesalcev temelji na dnevnem vzorčenju lokacij, pri čemer rezultate implicitno pogosto privzemamo kot reprezentativne za celotno 24-urno obdobje. Vendar je raziskanih vse več populacij, pri katerih se habitatni izbor cirkadiano spreminja, kar navaja k hipotezi, da se med deli dneva lahko razlikujejo tudi značilnosti HR. V raziskavi smo na osnovi 24-urne GPS telemetrije 15 osebkov analizirali razlike v velikosti in zgradbi dnevnih, nočnih in 24-urnih HR jelenjadi. Razlike v zgradbi smo prikazali na primeru binarne spremenljivke gozd-negozd. Ugotovili smo, da se nočni in zlasti 24-urni HR pretežno prekrivajo z dnevnimi (64 % oz. 76 % prekrivanje) in da se deli HR, ki jih jelenjad uporablja izključno ponoči, praviloma stikajo z njenimi dnevnimi HR ali pa so v njihovi neposredni okolici (mediana oddaljenosti 125 m). Razlike v velikostih HR so statistično značilne le med dnevnimi in 24-urnimi HR. Močno pa se razlikujejo zgradbe HR: delež negozdnih površin v dnevnih HR znaša 15 %, v 24-urnih 26 % in nočnih HR 31 %, zlasti velik (56 %) pa je v delih HR, ki jih jelenjad uporablja izključno ponoči. Pričujoča raziskava je pokazala, da v Sloveniji z dnevnim spremljanjem ni mogoče točno ugotoviti velikosti, še manj pa zgradbe 24-urnih HR jelenjadi. Več indicev kaže, da je podobno tudi pri mnogih drugih populacijah/vrstah. Zato se je pomembno zavedati, da so lahko značilnosti HR, ki so ugotovljene na osnovi dnevnih spremljav, pomanjkljive ali celo napačne, če jih generaliziramo na 24-urno obdobje

Effects of environmental factors on the wild boar (Sus scrofa l.) spatial distribution in Slovenia

Številčnost in območje razširjenosti divjega prašiča (Sus scrofa L.) sta se v Sloveniji in drugih evropskih državah v zadnjih desetletjih občutno povečalaposledično so narasle tudi škode, ki jih povzroča v kmetijstvu. V raziskavi smo preučili, kateri okoljski dejavniki ključno vplivajo na prostorsko razporeditev divjega prašiča, in za Slovenijo ugotovili njegovo sedanje in potencialno območje razširjenosti. Raziskava temelji na velikem vzorcu (N = 5.977) georeferenciranih lokacij odvzema prašiča iz vse Slovenije in GIS-podatkovnih plasteh (25 okoljskih spremenljivk). Analize kažejo, da so gostote divjega prašiča največje v območjih: (a) z večjo razpoložljivosti energijsko bogate hrane (odrasli sestoji listavcev, krmišča) in dostopnostjo kritja (kmetijske površine blizu gozda, sukcesijske površine)(b) kjer so temperature visoke, zime mile, z malo snega (verjetnost rabe narašča s temperaturo in upada s količino padavin). Njegova prostorska razporeditev je odvisna tudi od gozdnatosti in stopnje fragmentacije gozda. Zdaj poseljuje 55 % Slovenije, njegov potencialni habitat pa obsega 67 % države. Razširjenost inštevilčnost divjega prašiča se bosta zato verjetno še povečevala, zlasti če se bodo nadaljevali sedanji trendi okoljskih sprememb (naraščanje temperature,povečevanje gozdnatosti, izginjanje iglavcev).Population size and range of wild boar (Sus scrofa L.) have increased significantly during the past decades in Slovenia, as well as in other European countries. Simultaneously, this has caused an increase in agricultural damages. In this study, we examined the influence of various environmental factors on wild boar spatial distribution, and identified its current and potential population distribution range for Slovenia. The researchis based on a large sample (N = 5.977) of georeferenced locations of boar harvested from the entire country and on GIS data layers (25 environmental variables). Analyses revealed that wild boar densities are highest in areas: (a) with outstanding availability of energy-rich food items (i.e. adult deciduous forests with high hard mast production and supplemental feeding places) and good cover accessibility (i.e. agricultural areas near forests and early successional areas)(b) where the temperatures are high andwinters are mild with low snowfall (the probability of use increases with temperature and decreases with quantity of precipitation). Spatial distribution of wild boar also depends on the percentage of forests and the level of forest fragmentation (i.e. size of forest fragments). Currently, boars inhabit 55% of Slovenia, yet the potential habitat extends up to 67% of the country. The wild boar population size and range are therefore likely to increase, especially if the current trends of environmental changes continue, such as rising temperatures, increased forested area, and a decrease in coniferous trees

Effectiveness of wolf (Canis lupus) culling as a measure to reduce livestock depredations

Škoda, povzročena na domačih živalih, je ena glavnih težav pri ohranitvenem upravljanju z volkom (Canis lupus). Škodo se pogosto poskuša zmanjšati z odstrelom volkov. V pričujoči raziskavi smo analizirali učinke legalnega odstrela volkov na obseg škode v Sloveniji ter pripravili pregled podobnih raziskav iz tujine. V letih 1995-2009 je bilo legalno odstreljenih 51 volkov in zabeleženih 2221 primerov napadov volkov na domače živali. S statističnimi analizami nismo ugotovili nobenih vplivov odstrela volkov na višino škode. Učinkov odstrela ni bilo zaslediti niti tedaj, ko smo med seboj primerjali najbolj ekstremna leta. Naši rezultati se ujemajo z izsledki tujih raziskav, ki prav tako opozarjajo, da (v nasprotju s splošnim prepričanjem!) trajnostni lov volkov ni učinkovit ukrep za zmanjšanje škode. Odstrel postane učinkovit šele, če z njim iztrebimo celo populacijo ali odstranimo večino volkov iz večjega območja. Ker je škoda na drobnici v Sloveniji resen problem in ker odstrel volkov očitno nima želenega učinka, priporočamo, da se v prihodnje napori in sredstva osredotočijo v bolj učinkovite ukrepe.Livestock depredations are one of the main challenges in the management of thegrey wolf (Canis lupus) and culling of the wolves is a measure often used in an attempt to reduce damages. In the present study we analyzed effects of the legal wolf culling on livestock depredations in Slovenia and made a reviewof similar studies from other regions. 51 wolves were legally culled and2,221 attacks on livestock were recorded in Slovenia in 1995-2009. Our analysis did not show any effects of the culling on the number of depredationsduring the study period. No effects were detected even when the most extreme years were compared. Our results are in agreement with those fromother studies that showed that sustainable hunting of wolves is not an effective measure to reduce live-stock depredations. Wolf removal becomes efficient only when wolves are completely exterminated or when the majority ofwolves are removed from a large area. Because depredation of small live-stock in Slovenia presents a serious problem and since wolf culling does not seem to be efficient, we recommend that more attention and resources should be focused on more effective measures

Review of faecal pellet-group count methods for estimating deer numbers

Poznavanje številčnosti in lokalnih gostot populacij rastlinojedih parkljarjevje pomembno pri reševanju številnih upravljavskih in temeljno-bioloških vprašanj. Po svetu se za ocenjevanje številčnosti parkljarjev pogosto uporabljajo metode štetja kupčkov iztrebkov, ki pa so pri nas ostale več ali manj prezrte. Z namenom spodbujanja njihove rabe smo pripravili celosten pregled metod s priporočili za Slovenijo. Uveljavljena stadva načina izvedbe, t.j. s predhodnim čiščenjem in brez čiščenja kupčkov iztrebkovpri slednjem moramo oceniti tudi čas razgradnje iztrebkov, ki se lahko med mikrohabitati in letnimi časi močno spreminja, zato tega načina ne priporočamo. Vzorčenje lahko poteka na vzorčnih ploskvah različnih oblik in velikosti ali z metodo linijskega transektaizbira konkretne metode je odvisna od pričakovane gostote parkljarjev in preglednosti terena, ki pogojujemožnost zaznavanja iztrebkov. Zaradi heterogenosti habitatov je raziskovalno območje priporočljivo predhodno stratificirati po habitatni primernosti glede na pričakovane gostote parkljarjev. Stopnje iztrebljanja (t.j. število izločenih kupčkov iztrebkov / dan) se znotraj vrst spreminjajo glede na letni čas, spol in starost živali, vendar zaradi primerljivosti rezultatov svetujemo uporabo konstantnih stopenj (za jelenjad 25 in za srnjad 20 kupčkov iztrebkov) ter večkratno ponovitev vzorčenja v različnih letnih časih, s čimer pokrijemo sezonske razlike v rabi prostora. Na natančnost rezultatov vplivata predvsem priprava in izvedba vzorčenja, zato je treba tej fazi dela posvetiti veliko pozornost.Knowledge of abundance and local densities of deer populations is important inmanagement as well as in biological context. Faecal pellet-group count method, widely used around the world for estimating deer numbers, has been almost neglected in our country. Therefore, we have prepared a comprehensive overview of the method with recommendations for Slovenia to enhance its use. In principle, there are two ways to perform the faecal pellet-group count method, i.e. clearance plot and standing crop method. The latter is not recommended in a daily management practice, as it requires faecal pellet-groupdecay rate estimation, which is rather season and microhabitat specific. Sampling can be done on sampling plots of different shapes and sizesor with the line transect method. Sampling design depends on expected deer densities and ground cover dependent pellet-group detectability. Since distinct habitats are used differentially by the deer, study area stratification on specific habitat types regarding the expected deer densitiesis recommended. Within the species, defecation rates (i.e. number of pellet-groups per day) vary according to season, animal age and gendernevertheless, due to comparative reasons we recommend the use of constant defecation rates (i.e. 25 for the red deer, 20 for the roe deer, respectively). Moreover, multiple samplings are needed to cover seasonal variety in habitat use. Sampling design is of a major importance for the success of the method and has the biggest impact on the precision of deer numbers/densities estimates, therefore much effort should be devoted to this stage

Poškodovanost smreke zaradi grizenja in lupljenja skorje po jelenjadi (Cervus elaphus) glede na prostorsko razporeditev krmišč

Forest damages caused by red deer and some other large herbivore species occasionally feeding on tree bark, are a grave ecological and economic problem in many parts of the world. Winter supplemental feeding is commonly used to mitigate the problem, but its effects are poorly known. This study, carried out at Pohorje (Slovenia) and including over 2,300 trees, used binary logistic regression to analyse the effects of supplemental feeding and many other factors on the probability of bark stripping on spruce. The probability of bark stripping depends on distance from the forest edge, density, age and tree species diversity of stands, slope and aspect of terrain, and red deer densitycontrary to expectations, it is not related to distance from feeding places. As much as 35% of spruce trees were damaged. The damage was the highest in younger, denser pure spruce stands, whose favourable protective and microclimatic conditions (thinner snow cover, higher effective temperatures) make them a preferred winter habitat for red deer. They contain,however, little other food but bark. To prevent / diminish bark stripping we propose a stronger thinning of such stands. Supplemental feeding may reduce damage only in exceptional cases, when animals are lured and concentrated in less sensitive areas, but in general we advise against the use of this measure due to its other negative effects.Poškodbe gozdov, ki jih zaradi hranjenja z drevesno skorjo povzročajo jelenjad in nekatere druge vrste velikih rastlinojedov, so v mnogih delih sveta resen ekološki in ekonomski problem. Pogosto se ga skuša reševati z zimskim dopolnilnim krmljenjem, katerega učinki pa niso preučeni. V raziskavi,ki je potekala na Pohorju in je zajemala prek 2.300 dreves, smo z logistično regresijo analizirali vplive krmljenja in številnih drugih dejavnikov na pojavljanje poškodb smreke zaradi lupljenja. Pojavljanje poškodb je odvisno od oddaljenosti od gozdnega roba, gostote, starosti in vrstne pestrosti sestojev, nagiba in ekspozicije terena in gostote jelenjadi, proti pričakovanjem pa ne od oddaljenosti od krmiščpoškodovanih je bilo kar 35 % smrek. Zlasti so poškodovani mlajši, čisti, gosti smrekovi sestoji, saj so zaradi ugodnih varovalnih in mikro-klimatskih razmer (plitvejša snežna odeja, višje efektivne temperature) priljubljen zimski habitat jelenjadi, v katerem pa razen skorje skoraj ni hrane. Za preprečevanje poškodb zato svetujemo močnejša redčenja takih sestojev. S krmljenjem je verjetno škode mogoče zmanjšati le izjemoma, kadar z njim živali odtegnemo na manj občutljiva območja, sicer pa rabo tega ukrepa zaradi drugih negativnih učinkov v splošnem odsvetujemo

Impact of environmental factors on the appearance and distribution of dental fluorosis in roe deer (Capreolus capreolus L.) in eastern Slovenia

Povečane koncentracije fluoridov v okolju negativno vplivajo na številne živalske vrsteena najbolj vidnih posledic je nepravilni razvoj trdih zobnih tkiv oz. zobna fluoroza. Z ocenjevanjem stopnje zobne fluoroze pri vsej odrasli srnjadi, odvzeti iz vzhodne Slovenije v 10 lovsko-upravljavskih območjih leta 2007 (n = 7.158), izvedbo statističnih analiz v rastrskem GIS okolju z razmeroma veliko prostorsko ločljivostjo (1 km2) ter s kartografskim prikazom smo želeli: (i) ugotoviti razlike v pojavnosti in stopnji zobne fluoroze pri srnjadi različnih območij vzhodne Slovenije(ii) določiti vpliv glavnih virov emisij na stopnjo in pojavnost zobne fluoroze(iii) določiti najpomembnejše okoljske dejavnike, ki vplivajo na pojavnost zobne fluoroze. Ugotovili smo, da vzhodna Slovenija na splošno s fluoridi ni onesnažena, saj se zmerna in močna fluoroza pojavljata pri manj kot 1 % vzorcev84 % vzorcev ni kazalo fluoroze. Le v okolici največjega vira fluoridov v Sloveniji (tovarna aluminija) je večje območje velike obremenjenosti okolja s flouridi. Z multivariatnimi statistikami smo ugotovili, da na pojavnost in stopnjo fluoroze vplivajo: (i) oddaljenost od največjega vira emisij (94,6 % pojasnjene variance)(ii) starost srnjadi (5 % pojasnjene variance)(iii) oddaljenost od najbližjega gozdnega roba (0,7 % pojasnjene variance).Increased concentrations of fluorides in the environment have a negative impact on different animal species, which are manifested mainly with the irregular formation of the dental hard tissue, called dental fluorosis. With the assessment of dental fluorosis in every adult roe deer shot in eastern Slovenia in 10 Hunting Management Districts in 2007 (n = 7,158), implementation of statistical analyses in raster GIS environment with high resolution (1x1 km) and cartography, we wished to: (i) establish the differences in the appearance and distribution of dental fluorosis in roe deer from different areas of eastern Slovenia(ii) define the impact of the main sources of fluorides on the appearance and distribution of dental fluorosis(iii) determine the most important environmental factors that have an impact on the appearance of dental fluorosis. In general, eastern Slovenia is not polluted with fluorides, while less than 1% of samples showed moderate to severe dental fluorosis84% of samples showed no fluorosis at all. Only inthe vicinity of the most important source of fluorides in Slovenia (aluminium smelter), there is an area with extreme fluoride pollution of the environment. The multivariate statistics revealed that the appearance and distribution of dental fluorosis are influenced primarily by: (i) the distancefrom the most important point source - (94.6% of the total variance)(ii) the age of the analysed animal (5% of the total variance)and (iii) the distance from the nearest forest edge (0.7% of the total variance), respectively

Mjere u lovstvu i šumarstvu značajno utječu na gustoću populacije jelena običnog

Red deer (Cervus elaphus L.) is in many parts of the world ecologically important and highly popular game species. Its population densities and environmental impacts largely depend on habitat suitability, which in turn is under strong influence of humans. Wildlife management intentionally improves habitat suitability, while forestry\u27s impacts on red deer are mostly unintentional. In both disciplines the full extent of these impacts is poorly understood. To better understand habitat use and improve management of red deer, we studied the impacts of multiple environmental and historical factors, mostly anthropogenic, on red deer spatial distribution in Slovenia. We found that the probability of red deer presence and population density are higher close to locations of historic (> 100 years ago) red deer reintroduction sites and in large continuous forest complexes. The finding is important for forecasting future red deer distribution and population dynamics. Population density is also positively dependent on proximity to supplemental feeding sites, the proportion of spruce stands in pole-stage and the share of forest young growth, which is important for preventing unwanted impacts of red deer on forest. The approach used by this study and its results are also useful for improving habitat ranking of hunting grounds, which some countries use in wildlife management planning.Jelen obični (Cervus elaphus L.) je u mnogim dijelovima svijeta važna ekološka vrsta i popularna divljač, te kao takva ima značajan izravan utjecaj na čovjeka. Istovremeno može imati štetne posljedice na okoliš, posebice na šumarstvo. Težina ovih posljedica ovisi o gustoći populacija jelena običnog, što zauzvrat u značajnom stupnju ovisi o kvaliteti staništa i prijašnjem upravljanju ovom vrstom. Oba čimbenika snažno odražavaju ljudske utjecaje. Ovo istraživanje proučava utjecaje određenih okolišnih i povijesnih čimbenika, posebice onih antropogenih, na raširenost i lokalne gustoće populacija jelena običnog. Područje istraživanja je Slovenija, zemljopisno, klimatski i krajobrazno izuzetno raznovrsna država. Jelen obični je u povijesti istrijebljen i reintroduciran prije 100 godina na nekoliko mjesta, a također je i spontano imigrirao iz Mađarske (Slika 1). Danas je proširen na 60% površine države, ali nije još dosegao sva pogodna staništa zbog sporog širenja. Analiza je obuhvatila nezavisne varijable širokog raspona okolišnih varijabli i varijable “troškovna udaljenost”, koja prikazuje “težinu” disperzije jelena običnog od mjesta reintrodukcije, odnosno imigracije. Procjene lokalnih gustoća jelena običnog (zavisna varijabla) su dobivene pomoću dvije metode: podaci o izvršenim odstrjelnim kvotama i metodom brojanja izmeta. Vrijednosti varijabli su pripremljene na relativno finoj prostornoj rezoluciji (imajući na umu površinu cijelog područja) od 1 km2. U skladu s teorijom o višestrukom izboru staništa, zavisnost jelena običnog o okolišu je analizirana na dvije razine: 1) globalni doseg jelena običnog (nazočnost/nenazočnost) i 2) gustoće lokalnih populacija unutar područja raširenosti. Na obje razine je provedena bivarijatna (korelacija) i multivarijatna (regresija) analiza. Nazočnost jelena običnog je najvjerojatnija u blizini mjesta reintrodukcije, odnosno imigracije, što ističe važnost varijable “troškovna udaljenost”, te u velikim šumskim kompleksima, što ukazuje na pozitivan utjecaj udjela šume i veličinu šumske plohe te negativan utjecaj gustoće ruba šume (Tablica 1, Tablica 2). Ove varijable također utječu na gustoću populacije, koja raste s padom udaljenosti od hranilišta i pozitivno je vezana s udjelom sastojina u kojima dominira obična smreka. Korelacija također ukazuje na pozitivnu ovisnost s udjelom mladih sastojina (Tablica 1, Tablica 3). Troškovna udaljenost od mjesta reintrodukcije te udio i kontinuitet šume prikazuje ljudske intervencije u povijesti (nekadašnje upravljanje jelenom običnim i korištenje prostora od strane čovjeka). Poznavanje utjecaja ovih čimbenika na jelena običnog je stoga važno za razumijevanje prošlosti i predviđanje buduće dinamike populacije. Stanište jelena običnog u Sloveniji još uvijek nije u potpunosti nastanjeno i širenje se nastavlja. Stoga se očekuje kontinuirano širenje jelena običnog, imajući na umu da brzina ovisi o načinima upravljanja prostorom. Stanje je slično i u većini drugih europskih zemalja. Još je važnije poznavati utjecaje mjera u današnjem lovstvu i šumarstvu koje, mogu biti prilagođene s ciljem postizanja željenih utjecaja. Neke ustaljene prakse upravljanja često ostvaruju utjecaje suprotne željenima,i u budućnosti bi trebale biti ponovno razmatrane. U budućnosti bi više pozornosti trebalo posvetiti izboru mjesta na kojem bi se postavila hranilišta za jelensku divljač, a na nekim područjima bi se intenzitet prihranjivanja jelenske divljači trebao reducirati. Udio mladih stabala u šumama Slovenije je prenizak; stoga bi ili trebalo proširiti područja obnove šumskih sastojina ili osnovati krmne površine za divljač (remize). Upravljanje odnosima između šume i divljači zahtjeva suradnju djelatnika u lovstvu i djelatnika u šumarstvu. Metoda primijenjena u našem istraživanju također bi mogla biti korištena za poboljšanje bonitiranja lovišta za jelensku divljač, jer su procjene utjecaja pojedinih okolišnih čimbenika na kvalitetu staništa jelena običnog temeljene na kvantitativnoj analizi