The activity patterns of most terrestrial animals are regarded as being primarily influenced by l... more The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49˚79N in central Europe to 70˚009N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day– night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPScollars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey.
The effects of predation on ungulate populations depend on several factors. One of the most impor... more The effects of predation on ungulate populations depend on several factors. One of the most important factors is the proportion of predation that is additive or compensatory respectively to other mortality in the prey, i.e., the relative effect of top-down and bottom-up processes. We estimated Eurasian lynx (Lynx lynx) kill rate on roe deer (Capreolus capreolus) using radio-collared lynx. Kill rate was strongly affected by lynx social status. For males it was 4.85 ± 1.30 S.E. roe deer per 30 days, for females with kittens 6.23 ± 0.83 S.E. and for solitary females 2.71 ± 0.47 S.E. We found very weak support for effects of prey density (both for Type I (linear) and Type II (non-linear) functional responses) and of season (winter, summer) on lynx kill rate. Additionally, we analysed the growth rate in a roe deer population from 1985 to 2005 in an area, which lynx naturally re-colonized in 1996. The annual roe deer growth rate was lower after lynx re-colonized the study area, but it was...
Overvåking av gaupe i Skandinavia er i hovedsak basert på å registrere antall familiegrupper hver... more Overvåking av gaupe i Skandinavia er i hovedsak basert på å registrere antall familiegrupper hver vinter. Observasjoner av familiegrupper samles inn kontinuerlig gjennom hele registreringsperioden fra 1. oktober til 28. februar. Ut fra alle bekreftede observasjoner blir det beregnet hvor mange familiegrupper som lever i Norge det enkelte år før jakta starter. Beregningene tar utgangspunkt i såkalte avstandskriterier (AK) som benyttes til å skille eller gruppere familiegrupper. Avstandskriteriene er basert på maksimale forflytningsavstander hos radiomerkede gauper i Skandinavia. Målet med denne rapporten var å analysere forflytningsmønsteret hos radiomerkede hunngauper samlet inn fra ulike deler av Skandinavia, og beregne nye avstandskriterier for klassifisering av familiegrupper gjeldene for hele Skandinavia. De maksimale forflytningsavstandene hos hunngaupene økte raskt over tid, opp til 10 døgn, hvoretter forflytningsavstandene flatet ut til en asymptotisk verdi, som tilsvarer lev...
Semi-domestic reindeer (Rangifer tarandus) are the main prey for lynx (Lynx lynx) in northern Sca... more Semi-domestic reindeer (Rangifer tarandus) are the main prey for lynx (Lynx lynx) in northern Scandinavia. This causes large, but poorly documented, losses of reindeer. Although the compensation schemes differ between Norway and Sweden, there is a legal requirement in both Scandinavian countries that losses of semi-domestic reindeer to large carnivores should be fully compensated. The current level of compensation payment
The activity patterns of most terrestrial animals are regarded as being primarily influenced by l... more The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49˚79N in central Europe to 70˚009N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day– night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPScollars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey.
The effects of predation on ungulate populations depend on several factors. One of the most impor... more The effects of predation on ungulate populations depend on several factors. One of the most important factors is the proportion of predation that is additive or compensatory respectively to other mortality in the prey, i.e., the relative effect of top-down and bottom-up processes. We estimated Eurasian lynx (Lynx lynx) kill rate on roe deer (Capreolus capreolus) using radio-collared lynx. Kill rate was strongly affected by lynx social status. For males it was 4.85 ± 1.30 S.E. roe deer per 30 days, for females with kittens 6.23 ± 0.83 S.E. and for solitary females 2.71 ± 0.47 S.E. We found very weak support for effects of prey density (both for Type I (linear) and Type II (non-linear) functional responses) and of season (winter, summer) on lynx kill rate. Additionally, we analysed the growth rate in a roe deer population from 1985 to 2005 in an area, which lynx naturally re-colonized in 1996. The annual roe deer growth rate was lower after lynx re-colonized the study area, but it was...
Overvåking av gaupe i Skandinavia er i hovedsak basert på å registrere antall familiegrupper hver... more Overvåking av gaupe i Skandinavia er i hovedsak basert på å registrere antall familiegrupper hver vinter. Observasjoner av familiegrupper samles inn kontinuerlig gjennom hele registreringsperioden fra 1. oktober til 28. februar. Ut fra alle bekreftede observasjoner blir det beregnet hvor mange familiegrupper som lever i Norge det enkelte år før jakta starter. Beregningene tar utgangspunkt i såkalte avstandskriterier (AK) som benyttes til å skille eller gruppere familiegrupper. Avstandskriteriene er basert på maksimale forflytningsavstander hos radiomerkede gauper i Skandinavia. Målet med denne rapporten var å analysere forflytningsmønsteret hos radiomerkede hunngauper samlet inn fra ulike deler av Skandinavia, og beregne nye avstandskriterier for klassifisering av familiegrupper gjeldene for hele Skandinavia. De maksimale forflytningsavstandene hos hunngaupene økte raskt over tid, opp til 10 døgn, hvoretter forflytningsavstandene flatet ut til en asymptotisk verdi, som tilsvarer lev...
Semi-domestic reindeer (Rangifer tarandus) are the main prey for lynx (Lynx lynx) in northern Sca... more Semi-domestic reindeer (Rangifer tarandus) are the main prey for lynx (Lynx lynx) in northern Scandinavia. This causes large, but poorly documented, losses of reindeer. Although the compensation schemes differ between Norway and Sweden, there is a legal requirement in both Scandinavian countries that losses of semi-domestic reindeer to large carnivores should be fully compensated. The current level of compensation payment
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Papers by Henrik Andrén
been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network
of studies conducted with identical methodology in different areas spanning latitudes from 49˚79N in central Europe to 70˚009N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day–
night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPScollars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily
activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most
important prey.
been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network
of studies conducted with identical methodology in different areas spanning latitudes from 49˚79N in central Europe to 70˚009N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day–
night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPScollars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily
activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most
important prey.