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The influence of environmental and human factors on group sizes of large ungulates is still poorly understood, especially when considered at multiple timescales. We analyzed long-term data of red deer (Cervus elaphus) group sizes collected at 3 timescales in Białwieża Primeval Forest, Poland, from 1986 to 2003. On the daily scale, group size differed among periods of the day for females in summer (P = 0.001) and autumn (P = 0.04) but not winter (P = 0.18). Group size of males did not differ (P > 0.35) among the periods of day during any season. On the seasonal scale, both sexes had larger group sizes in winter than summer, and males were always more solitary than females. At the annual scale, multiple-regression analysis explained 96% (r² = 0.957) of deer grouping patterns. Human hunting had the greatest influence (sr²i = 0.414), followed by acorn crop (sr²i = 0.012) and snow cover (sr²i = 0.008). Intense hunting by humans during a 5-year period appeared to cause increases in group sizes, even while red deer densities decreased. The disruption of the normally positive relationship of deer density to group size apparently affected predator-prey relationships, consequently red deer numbers continued to decline even after hunting pressure was relaxed. Our results indicate caution should be used when reducing red deer numbers by dramatic increases in hunting because the resulting behavioral and ecological changes in deer have implications that extend well beyond the season and year, with important consequences for the long-term stability of the population, especially in areas where large carnivores are present. [ABSTRACT FROM AUTHOR]

The cover image, by Sabina Nowak et al., is based on the Biodiversity Research Sedentary but not dispersing wolves Canis lupus recolonizing western Poland (2001–2016) conform to the predictions of a habitat suitability model, DOI: 10.1111/ddi.12621. Photo Credit: Robert Myslajek. [ABSTRACT FROM AUTHOR]

Anti-predator responses by ungulates can be based on habitat features or on the near-imminent threat of predators. In dense forest, cues that ungulates use to assess predation risk likely differ from half-open landscapes, as scent relative to sight is predicted to be more important. We studied, in the Białowieża Primeval Forest (Poland), whether perceived predation risk in red deer (Cervus elaphus) and wild boar (Sus scrofa) is related to habitat visibility or olfactory cues of a predator. We used camera traps in two different set-ups to record undisturbed ungulate behavior and fresh wolf (Canis lupus) scats as olfactory cue. Habitat visibility at fixed locations in deciduous old growth forest affected neither vigilance levels nor visitation rate and cumulative visitation time of both ungulate species. However, red deer showed a more than two-fold increase of vigilance level from 22% of the time present on control plots to 46% on experimental plots containing one wolf scat. Higher vigilance came at the expense of time spent foraging, which decreased from 32% to 12% while exposed to the wolf scat. These behavioral changes were most pronounced during the first week of the experiment but continuous monitoring of the plots suggested that they might last for several weeks. Wild boar did not show behavioral responses indicating higher perceived predation risk. Visitation rate and cumulative visitation time were not affected by the presence of a wolf scat in both ungulate species. The current study showed that perceived predation risk in red deer and wild boar is not related to habitat visibility in a dense forest ecosystem. However, olfactory cues of wolves affected foraging behavior of their preferred prey species red deer. We showed that odor of wolves in an ecologically equivalent dose is sufficient to create fine-scale risk factors for red deer. [ABSTRACT FROM AUTHOR]