Highlights d Ungulates moved to track forage in landscapes with wavelike spring green-up d Patterns of green-up explained where migratory behavior occurred in many ecosystems d At the species level, migrants and residents received equivalent foraging benefits d Movement tactics represent behavioral adaptations to specific landscapes
The most common framework under which ungulate migration is studied predicts that it is driven by spatio–temporal variation in plant phenology, yet other hypotheses may explain differences within and between species. To disentangle more complex patterns than those based on single species/ single populations, we quantified migration variability using two sympatric ungulate species differing in their foraging strategy, mating system and physiological constraints due to body size. We related observed variation to a set of hypotheses. We used GPS‐collar data from 537 individuals in 10 roe Capreolus capreolus and 12 red deer Cervus elaphus populations spanning environmental gradients across Europe to assess variation in migration propensity, distance and timing. Using time‐to‐event models, we explored how the probability of migration varied in relation to sex, landscape (e.g. topography, forest cover) and temporally‐varying environmental factors (e.g. plant green‐up, snow cover). Migration propensity varied across study areas. Red deer were, on average, three times more migratory than roe deer (56% versus 18%). This relationship was mainly driven by red deer males which were twice as migratory as females (82% versus 38%). The probability of roe deer migration was similar between sexes. Roe deer (both sexes) migrated earliest in spring. While territorial male roe deer migrated last in autumn, male and female red deer migrated around the same time in autumn, likely due to their polygynous mating system. Plant productivity determined the onset of spring migration in both species, but if plant productivity on winter ranges was sufficiently high, roe deer were less likely to leave. In autumn, migration coincided with reduced plant productivity for both species. This relationship was stronger for red deer. Our results confirm that ungulate migration is influenced by plant phenology, but in a novel way, that these effects appear to be modulated by species‐specific traits, especially mating strategies.
Mortality in radio-marked European roe deer (Capreolus capreolus (Linnaeus, 1758)) neonates was studied during 14 years in a mixed forestagricultural landscape in Sweden. A total of 233 fawns were marked. Births were synchronized, with 79% occurring during 25 days and a peak between 25 May and 7 June encompassing 62% of the births. Overall mortality was 42%, but in three single years, it exceeded 85%. Predation by red fox (Vulpes vulpes Desmarest, 1820) accounted for 81% of total mortality. The effects of age, sex, and time of birth on the vulnerability to predation were analysed. Fawns born just after the birth peak had the lowest predation risk. Predation rate was highest for the fawns that had the very earliest or the very latest birth dates. Predation thereby seems to strengthen the birth synchrony in roe deer. Contrary to earlier published findings, there was no difference in susceptibility to predation between the sexes. Also differing from earlier findings was that predation rate was highest during the first week of life and declined thereafter almost linearly. The majority of the fawns (85%) were killed before 30 days of age and 98% before 40 days. Different types of landscapes may explain the discrepancies between our study and earlier findings.
Besides red fox Vulpes vulpes predation, mowing is probably the most important mortality factor for roe deer Capreolus capreolus neonates in areas of intensive agriculture. Using radio‐transmitters on roe deer neonates in south‐central Sweden, I estimated mortality caused by mowing and tested and evaluated a traditional method to decrease this kind of mortality. During 1997–1999 fawn mortality caused by mowing was estimated at 25–44% of the yearly recruitment. Fawns were at risk for at least up to one month of age. The method tested uses scaring devices made of plastic sacks that are set out before mowing. The idea is that this will prevent female roe deer from placing their fawns in the field and make them remove the ones already hiding there. Black plastic sacks were attached to approximately 2‐m long poles and placed in hay fields where marked fawns were bedded. During 1998–1999,14 separate experiments were performed. Out of 22 fawns bedded in the vicinity of sacks, 18 were removed the day after the sacks were set out and three were removed on the second day. The fawns were always removed to another field or habitat patch. Fawns in the experiments were removed to a higher degree than fawns used as a control, and they were moved longer distances than both control fawns and the distances moved during the days before the experiment. The results imply that the use of this method is effective in reducing the mortality of roe deer fawns.
Red deer Cervus elaphus is a highly appreciated and intensively managed game species throughout Europe. A common management objective is a sustainable harvest of large trophies. In southern Sweden, management has mainly aimed at preserving the nominate subspecies C. elaphus elaphus. Seasonal migration of red deer males may, however, complicate both harvest management as well as conservation efforts. I used individually identified male red deer in southern Sweden to observe distance travelled from rutting areas to areas used by males in summer and winter. Adult males were identified by antler shape and photodocumented during rut. Photos from the rut were compared to trophies of deer harvested or found dead, to found cast antlers and to stags photographed during summer. From 1969 to 2007, a distance between rutting ground and summer/winter quarters was established for 96 identified stags. An average distance of 14 km and a maximum distance of 47 km were recorded between rut and summer/ winter observations. The seasonal migration of males increases the risk of overexploitation of males with harvest in both rutting areas and wintering areas. Harvest management and conservation efforts may fail if males seasonally migrate outside the management unit. The results suggest that seasonal migration must be considered in harvest management and conservation and that there is a need for a regulation of male harvest. Furthermore, the study stresses that the success in deer management of single hunting units, may be largely dependent on the harvest policies in the near surroundings as well as in areas tenths of kilometres away, suggesting that a successful management must rely on cooperation and co-ordination on a landscape scale.
We studied the impact of red fox (Vulpes vulpes) predation on free‐ranging roe deer (Capreolus capreolus) neonates during 14 years in a mixed forest/agricultural landscape in south central Sweden. A large‐scale natural predator removal experiment occurred when an outbreak of sarcoptic mange (Sarcoptes scabiei) reduced the red fox population initially and caused subsequent variations in red fox abundance. We estimated relative red fox abundance by dividing number of fox observations with number of person‐days in field. Red fox predation accounted for 88% of known mortality in roe deer fawns. Predation was closely correlated to red fox abundance, and there was a strong negative correlation between fox abundance and overall fawn survival. Fox abundance was the only factor with a significant effect on between year variation in fawn survival. Annual predation varied between zero and 90%. Our study recorded the highest predation rates for roe deer juveniles established to date. High fawn survival in years of low fox abundance suggested that predation mortality was additive during summer. Our results supported the conclusion that the large national increase of roe deer in Sweden during the 1980s and 1990s was related to lower fox predation on fawns and also indicated that the roe deer population density was well below habitat carrying capacity at the onset of the mange epidemic. In Sweden, in general, a thorough fox control will most likely result in increased fawn survival and higher potential roe deer harvest.
Abstract. Deer (Cervidae) cause considerable damage to forest plantations, crops, and protected habitats.The most common response to this damage is to implement strategies to lower population densities. However, lowering deer density may not always be desirable from hunting, recreational, or conservation perspectives. Therefore, knowledge is needed about additional factors beyond deer density that affect damage levels, and management actions that consider competing management goals. We studied the relationships between levels of bark-stripping by red deer (Cervus elaphus) on Norway spruce (Picea abies) and (1) relative deer density indices (pellet group count and deer harvest data), (2) availability of alternative natural forage (cover of forage species) and (3) proportion forest in the landscape, both at a forest stand scale and at a landscape scale. Extensive variation in damage level was evident between the six study areas. On a stand scale, the proportion of spruce damaged was positively related to pellet group density, indicating the importance of local deer usage of stands. In addition, available alternative forage in the field layer within spruce stands and proportion forest surrounding stands was negatively related to damage level. On the landscape scale, damage level was negatively related to availability of forage in the field and shrub layers and proportion forest, but was not related to any of the relative deer density indices. Increasing alternative forage may thus decrease damage and thereby reduce conflicts. Additionally, the proportion of forest in the landscape affects damage levels and should thus be considered in landscape planning and when forecasting damage risk. The relationship between local deer usage of stands and damage level suggests that future studies should try to separate the effects of local deer usage and deer density.
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