First findings of brown hare (Lepus europaeus) reintroduction in relation to seasonal impact

Abstract

In Europe, brown hare (Lepus europaeus) populations have been declining steadily since the 1970s. Gamekeepers can help to support brown hare wild populations by releasing cage-reared hares into the wild. Survival rates of cage-reared hares has been investigated in previous studies, however, survival times in relation to seasonality, which likely plays a crucial role for the efficacy of this management strategy, has not been evaluated. Here we examine the survival duration and daytime home ranges of 22 hares released and radio-tracked during different periods of the year in East Bohemia, Czech Republic. The majority of hares (82%) died within the first six months after release, and 41% individuals died within the first 10 days. Significant differences were found in the duration of survival with respect to the release date. Hares released in the summer months (July and August) survived the longest (on average 103.2 days, SD ± 23.8) and hares released throughout all other months of the year survived for significantly shorter periods of time (on average 20.4 days, SD ± 11.5). The most likely cause of death was red fox predation (38.9%) followed by disease (coccidiosis and other health problems) (27.8%). Three hares (16.6%) were killed by automobile traffic. After six months of radiotracking, we found the average survival time of all hares released was 58 (SD ± 70.9) days. Hares in this study preferred to remain in the vicinity of the release area and the average distance from release point to the center of the home range was 471 m.

Fig 1. Statistical comparison of the mean survival duration of released hares with respect to the cause of death.

The numerical values above each bar show mean values for each cause of death, and lettered indexes above the bars indicate statistical. Error bars depict mean ± standard error.

Fig 2

Survival duration of hares according to cause of death: red–predation by red foxes, yellow–health problems, black–lost transmitter, gray – hit by car, white–unidentified, green–survived monitoring period. Gray axis below depicts days from individual release.

Fig 3. Survival days in relation to the release date of brown hare.

The labels above the bars show the mean value of each variant. Error bars depict mean ± standard error.

Fig 4. Agricultural field area percentage relative to inactive home range size.

Bold line depicts regression function described in the plot. P-values for logarithmic regression assume a null hypothesis based on parameter a of the regression equation y = a * log(x) + b is equal to zero. Natural logarithm was used for regression function.

Fig 5. Meadow area percentage relative to the size of inactive home ranges.

Bold line depicts regression functions described in the plot. Provided p-values for logarithmic regression assume a null hypothesis based on parameter a of the regression equation y = a * log(x) + b is equal to zero. Natural logarithm was used for regression function.