As one of the most abundant game species in Europe, European wild boar (Sus scrofa) populations prove highly adaptable to cultivated landscapes. The ongoing process of climate change and the high agricultural yields seem to further optimize the living conditions for this species. In long-term reproduction monitoring, we collected data on the body weight of wild boar females. Over an 18-year period, the body weight of wild boar females increased continuously, then stopped and decreased. It was possible to detect differences between the body weights of animals from forest and agricultural areas. For these areas, differences in body weight development also led to a significant distinction in the onset of puberty. We conclude that, even in a highly cultivated landscape, forested areas provide habitat characteristics that may strongly influence reproduction. Second, with dominant agricultural areas in Germany, wild boar reproduction has been favored in recent decades.

Background: The wild boar population in Europe is steadily growing, one of the reasons for this increase probably being the high reproductive potential of this large mammal. Population management is important to stabilise wild boar numbers and a great deal of attention is focusing on the reasons, which might contribute to the high reproductive rates. Understanding the timing of puberty attainment provides information required for proper management practices. Knowledge of the earliest expected time of sexual maturation in male wild boars is limited, research being mostly focused on females. Previous hunting references indicate that sexual maturity in males occurs in the second year after birth. In contrast, male domestic pigs become sexually mature from about seven months of age. Thus, aims of this study were to investigate (1) whether there is a physiological ability for reproduction also in male wild boars of a younger age and (2) whether the body weight of wild boar males has a more important role than age in driving the maturation of the testis.Methods: Male wild boar individuals were sampled during hunting drives in the eastern part of Lower Saxony in Germany. Testes with epididymides from 74 males were collected and prepared for histological examination and immunohistochemistry. The reproductive status could be ascertained based on development/occurrence of different germ cell populations using histology and based on the immunohistochemical detection of the anti-Müllerian hormone and androgen receptor.Results: In this study, male wild boars aged nine to ten months already passed puberty and were able to reproduce if they had reached the appropriate body condition of about 29 kg dressed weight. Immunopositivity to the anti-Müllerian hormone in Sertoli cells was evident only in prepubertal animals and decreased with the onset of puberty. No immunoreaction was evident at postpuberty. The androgen receptor was detected in Sertoli cells, peritubular cells and Leydig cells, surprisingly already in Sertoli cells of prepubertal wild boars as well depending on body weight. Moreover, two-thirds of young males aged about ten months were precociously reproductively mature, showing histologically the presence of spermatozoa in testes and epididymides.Conclusions: As piglets are mostly born in spring, also these young male individuals could target the heat of female wild boars in the winter months, resulting in the observed population increase. Therefore, a reduction in wild boar numbers should also focus on piglets of both sexes.

Analyses of sexual steroid hormones in wild boars are rarely described. Testosterone (T) and 17β-estradiol (E2) concentrations are useful to recognize sexual maturation. As threshold values for this species are unknown, additional parameters are required. A total of 127 blood samples from wild boar males were collected to measure T and E2. Age and weight were recorded. Thirty-one epididymides were sampled too. Males were sorted into pre-and postpubertal groups based on the absence/presence of spermatozoa in epididymides and on morphological data following previous results. Forty-four males were prepubertal: the mean age and weight were 10 months and 23 kg, respectively. They showed no spermatozoa. The mean concentrations of T and E2 were 1.2 ± 1.2 ng/mL and 39.7 ± 120.3 pg/mL, respectively. Sixty-six males were postpubertal, twenty-nine of which presented spermatozoa. Their mean concentration of T was 7.6 ± 6.3 ng/mL and E2 was 664.3 ± 250.4 pg/mL. Seventeen samples could not be defined; the hormone concentrations between the two groups suggested a transitional phase consistent with puberty. Wild boars before 12 months of age had high hormone levels like older boars, indicating that they could attempt to reproduce. Hormones at the end of the mating season (January) were high so that reproduction could occur thereafter, shifting farrowing from spring to summer.

The Northern German Black Grouse metapopulation has been affected since decades by a sharply decline that has ultimately led to a reduced genetic variability. Gastrointestinal parasitoses are common among Black Grouse, but it is not clear if they have a further negative impact on the development of this already threatened metapopulation. Therefore, between 2011 and 2014, the occurrence and seasonal variation of gastrointestinal parasites were assessed by coproscopical investigations of Black Grouse feces collected in the nature conservation area of the “Lüneburg Heath”. Feces were obtained also from individuals during capture and re-capture activities. In total, 1,187 fecal samples were analyzed, of which 365 were caecal and 822 were rectal feces samples. 86% of the caecal and 95% of the rectal feces samples were parasite negative. Of the positive samples, oocysts of Coccidia spp. showed the highest prevalences of 12.1% in caecal and 1.1% in rectal samples, respectively. Helminths of the species/genera Trichostrongylus tenuis, Ascaridia spp., Heterakis spp., Capillaria spp., and Syngamus trachea were also observed, but at remarkably lower prevalences. High and moderate excretion intensities were observed only for coccidian oocysts. Coccidian infections revealed a seasonal pattern, occurring mostly during autumn and winter. Nematode eggs occurred more frequently in spring and summer. Four of the seven Black Grouse that were caught and equipped with GPS transmitters, presented high excretion intensities of coccidian oocysts. Despite high/moderate oocyst excretion, no negative health impact was observed, suggesting low pathogenicity of the infecting coccidia species or subsided infections. In contrast to previous studies, this Black Grouse population showed low prevalences of a rather narrow spectrum of parasites. We did not observe any negative impact of parasite infections on this population, which could be responsible for its decline. Thus, causes of decline are to be ascribed to other proximate and ultimate factors.