Information on mating and reproductive behaviour in wild mustelids remains limited and is almost exclusively based on captive studies. The same is true for the steppe polecat (Mustela eversmanii), a particularly elusive species that is endangered in Europe. In the Czech Republic, we used camera traps to capture steppe polecats mating in the wild, documenting the sequence in detail. The footage revealed previously undescribed male behaviours, including long-term den monitoring, burrow modification, and provisioning of nesting material. Copulation began at approximately 07:00, during daylight, above ground, with several mating bouts, the longest recorded lasting at least 21 min. After copulation, the male guarded the female for more than one and a half hours, repeatedly preventing her from leaving the burrow area. These observations are consistent with patterns described in captivity but substantially extend our existing knowledge by documenting complex pre- and post-copulatory behaviour under natural conditions.
Most cobitid loaches (Cypriniformes: Cobitidae) exhibit pronounced sexual dimorphism associated with mating behaviour. However, empirical evidence linking this differentiation in mating-related morphology to reproductive isolation remains limited. In Japan, the dojo loach (Misgurnus anguillicaudatus sensu lato) comprises two distinct species: a cryptic species (Misgurnus sp. Type I sensu Okada et al. (2017), Type I loach) and a common species (M. anguillicaudatus, Type II loach), which co-exist without hybridisation in the Reinan region of Fukui Prefecture, central Honshu Island. Previous morphological comparisons have revealed differences in traits related to mating behaviour between the two loaches, indicating possible mechanical and behavioural isolation. Aquarium observations revealed that both species exhibited a common mating sequence consisting of five phases: approaching and following, parallel swimming and lifting, fixation, coiling and egg release, and separation. During coiling, the male's elongated pectoral fin and lamina circularis supported the female's abdomen, whereas the raised ridges stabilised the spawning posture. Type II males, which possessed more developed mating-related morphological traits, exhibited significantly longer coiling durations than Type I males. This association between morphology and behaviour suggests that these traits could function as behavioural and/or mechanical barriers during interspecific mating.
Sex identification and sex-specific behaviour are fundamental to fish reproductive ecology, yet their spatial variation along environmental gradients remains insufficiently understood. Adult brown trout (Salmo trutta) were sampled during the spawning period at 43 stream sites, each with at least three adult trout. We investigated sex ratios and morphometric characteristics (length, weight, and relative head length) of brown trout in relation to altitude, Strahler stream order, stream depth range, and mean stream depth across the Bohemian Forest (Central Europe). In total, 311 individuals were sexed. Males were significantly larger and had relatively longer heads than females. The proportion of males increased significantly with altitude, indicating a male-biased sex ratio in higher-elevation streams. Fish weight decreased with altitude along upstream-downstream gradients, suggesting that environmental conditions at higher elevations may constrain growth and body size. Measured temperature, Strahler stream order, and depth range had no detectable effect on brown trout sex ratios and morphometric characteristics. These results indicate sex-specific spatial segregation during the spawning period, likely driven by differences in migratory behaviour, competition, and energetic constraints, highlighting the role of natural environmental gradients in shaping salmonid population structure.
In the sand goby, Pomatoschistus minutus, males build nests and provide sole care for the eggs until hatching. We examined whether male and female courtship before spawning were associated with subsequent filial cannibalism by the male. Full and partial brood cannibalism showed distinct patterns. Broods that were later completely cannibalised were smaller, and spawning occurred later than in broods of males that received continued care. In contrast, brood size was not correlated with the extent of partial brood cannibalism. Instead, female courtship was negatively associated with partial brood cannibalism, whereas no similar relationship was found for male courtship. These results are consistent with full and partial brood cannibalism reflecting different biological mechanisms. Female courtship may provide information about future male care, influence subsequent male behaviour, or covary with brood or egg quality.
Ophidiomyces ophidiicola (Oo) is a snake fungal pathogen that causes ophidiomycosis. The disease manifests as dermatomycosis and/or systemic mycosis, and can be fatal. It occurs in free-ranging snakes in Asia, Europe and the USA and has also been demonstrated in captive snakes. We tested for the presence of Oo in free-ranging snake populations in the Czech and Slovak Republics (n = 420) between 2019 and 2022, focusing mainly on grass snakes (Natrix natrix) and dice snakes (Natrix tessellata), as well as various captive exotic species (n = 207). After collecting skin swabs, we tested for Oo using the qPCR method. We confirmed fragmented occurrence of Oo in the Czech Republic (total prevalence 15%) and recorded Oo in the Slovak Republic for the first time (total prevalence 33.9%). The highest prevalence was observed in N. tessellata (20.2%), which appears to be the most susceptible species. The pathogen was not detected in captive snakes.
