The study includes mating and spawning data of freshwater crayfish, Austropotamobius pallipes Lereboullet, obtained in four consecutive years (1987)(1988)(1989)(1990). A total number of 586 wild-caught female A. pallipes in the 21-65 mm to 45-60mm carapace length (CL) size were held under laboratory conditions at different dates in September-October. Initial densities at mating time were 21 and 24 erayfish/m' with a 1:2 malc:female ratio. High percentages of mating were obtained (97 4-100%) exeept in 1989 (57-5%). ln all years, most of the maiings (90%) were concentrated in a period of 8-12 days with mean water temperatures between 12''C and 13 5°C. Spawning took place a few days after mating (minimum 2 days, maximum 14 days) at mean water temperatures between H^^C and lO-B^C. In the firet 3 years, almost 100% of mated females spawned. However, in the fourth year (1990), when the mean size of erayfish was smaller, only 72-4% of mated females spawned. The mean number of pteopodal eggs was 64 (maximum 220, minimum 18). Egg diameter ranged between 2-30 and 3 25 mm (mean value 2-78 mm). Pleopodal egg number was positively correlated with earapaee length (r = 0 72). Correspondence: Dr Jos

This study aimed to evaluate the postrelease survival and spatial distribution of farm-bred red-legged partridges (Alectoris rufa) that were subject to a prerelease training program based on exemplary behavior and alarm calls given by adults that acted as experienced demonstrators in simulated predator encounters (wooden raptor models and humans). Two groups of partridges were released in this study: trained (intensively reared birds accompanied by tutors) and control (chicks reared without tutors). Releases were conducted in the fall and winter-spring during 2 consecutive years using a total of 44 trained and 40 control radio-tagged partridges. Trained partridges showed statistically higher mean values of survival (72.7 d), home range (13.04 ha), and dispersion (549.58 m) compared with nontrained partridges, with most nontrained birds failing to survive more than 2 wk after release. Trained adult partridges showed the best survival results (105.2 d). Taking all birds into account, causes of death were attributed to terrestrial predators (45%), raptors (18.7%), hunting (11.3%), and unknown causes (25%). Although values of variables reported here were lower than those reported in wild counterparts, survival time and spatial behavior of trained birds were close to that of previous data of parent-reared partridges and higher than that of farm-bred birds. This study aimed to confirm the potential of prerelease training techniques in present-day rearing systems. Farm-bred game birds, which normally suffer from high predation rates after release, could highly benefit from the use of cost-effective training techniques based on learning from experienced adults.

1. On a private property with a stable population of wild red-legged partridge (Alectoris rufa) and an appropriate habitat for the survival of the species, reinforcement repopulations were carried out in the months of October and November for two consecutive years using 5- to 6-month-old birds reared on a commercial game farm. 2. Of the 36 released birds, none was still alive by the following spring's breeding period. Mean survival time was 9.4 d in the first year and 7.6 d in the second year. 3. Seventy-two per cent of mortality was attributable to predation, 11% to hunting and 17% to doubtful causes of death, accidents and starvation. 4. Post-release mean dispersion was 377.8 m in the first year and 526.3 m in the second. Mean home range was 7.1 ha in the first year and 5.4 ha in the second. 5. The production systems and handling practices of commercial game farms may have modified some anti-predator ethological patterns and strategies, which might make it more difficult for the birds to adapt and integrate into the wild, resulting in reduced survival due to premature mortality.

No abstract

On a private property with a stable population of wild Red-Legged partridge (Alectoris rufa) and an appropriate habitat for the survival of the species, reinforcement repopulations were carried out using 54 birds that were 2 to 3 mo old and reared on a commercial game farm. This study aimed to evaluate the effectiveness of repopulations, the behavior in the wild of released partridges, and the possible causes of success or failure of reinforcement population operations. The releases were carried out during August and September of 2 consecutive years. All birds were equipped with radio transmitter collars to determine their behavior after release. Two release methods were used in yr 1: an acclimatization cage (AC) method and a direct release method on the day of the birds arrival (DR). The aim of the release in yr 2 was to collect data to determine the influence of year conditions using the DR method. Of the 54 released birds, none remained alive by the time of the reproductive period in the following spring. The mean survival time was 16.79 d for the AC method and was 11.89 and 5 d for the DR method in yr 1 and 2, respectively. Of the recorded mortalities, we assigned 81.13% to predation, 7.55% to hunting, and 11.32% to unknown causes of death, accidents, or starvation. Repopulation was not successful at providing a long-term increase in partridge numbers, with most birds falling victim to predation within 1 mo of release. Dispersion is the maximum distance from the release point at which each bird was located. The postrelease mean dispersion was 437.65 m for the AC method and was 647.57 and 266.07 m for the DR method in yr 1 and 2, respectively.

No abstract

The egg development of the freshwater crayfish (Pacifastacus leniusculus Dana) under laboratory conditions is studied in this work from spawning to hatching. The sequence of its development is presented here, and the chronology of the different embryonic phases is established at one specific temperature (15.5 degrees +/- 1 degree C).

No abstract