Two males of Neurergus strauchii barani sniffing at each other, picking up cues about each others’ sexual identity. Photo: S. Bogaerts. 

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... test (N = (n +  x n2 +/ R + ) – ) gives a total estimate of 24 breeding individuals. The standard error provided by Seber (982) for Chapman’s test leads to a total population size of 24 ± 02 (minimum 39 and maximum 343 adults). A Bayesian approach, as presented by Pellet & Pellet (2003), may be more adequate, yield- ing a more precise outcome than the classical Lincoln- Petersen’s test. We performed it in the manner of Pellet & Pellet (2003), resulting in the breeding population to comprise 305 individuals. Multiplying the standard error with 2, the confidence interval shows indeed that the er- ror is wide. The actual breeding population size is some- where between 4 and 445. Here, the confidence interval is already large as a consequence of the fact that we had only two sampling dates. The estimate solely concerns the breeding population over a small straight stretch of stream, so that it only gives a partial estimate of the total population of N. strauchii bara- ni at this location, which of course also includes juveniles and subadults not found in the breeding water. We also cannot exclude the possibility that animals have drifted off with the stream outside the research area. Because of the low numbers of recapture and the fact that our capture-re- capture method does not fulfill all requirements for closed- population estimates, the range of error is large. In our case these limitations probably have a limited effect, as shown in comparable estimates (see Kendall 999). However, in light of the limitations and uncertainties our calculations can only be very provisional. Sex ratios differed slightly between 7 and 3 April (Table ). Males outnumbered females on both occasions. On the basis of the few data we have, we assume that males enter the breeding site earlier than females. On other occasions in previous years we had found an equal sex ratio or a clearly female-biased number, but in 2005 and 2007 there was less snow cover, and breeding probably started earlier (Table ). We conclude that apparently the aquatic period of breed- ing N. strauchii, at least in the population of the subspecies studied by us, is restricted to roughly three months, start- ing just after thaw and lasting until the beginning of sum- mer. In more eastern locations where N. s. strauchii occurs, breeding can be delayed, depending on the onset of thaw; Schmidtler (994) on 5 June 976 found freshly laid eggs near Bitlis, Bitlis Province, Turkey, roughly 330 km east of Kubbe Mountain. Stream width and water temperatures had changed enormously between the two visits ( Table 2), changing from slow-moving and about  m wide to about twice as wide and running much faster. The water temperature had dropped to 2.5° C, but this did not result in a noticeable change of activity pattern of the newts. Notwithstanding the low temperature males and females were very active and showed reproductive behav- iour. We could observe both male-female and male-male interactions. Movements were slow. Males approached one another, taking up positions more or less face-to-face and sniffing at each other (Fig. 2), checking sexual iden- tity. Then, having identified the other animal as male, they would move away, or remain standing still opposite and facing each other with their tails bent (Fig. 3). We did not observe physical contact between males or other forms of interaction, which could be interpreted as aggressive be- haviour. Two males were seen approaching a female near the stream’s edge and fan their tails in the direction of the female, a form of courtship common to Neurergus and oth- er newt species (see Sparreboom et al. 2000). Eggs were not found and egg-laying was not observed. Previous authors reported 9–0 °C and 0.9 °C, respec- tively, as the lowest temperatures recorded for breeding N. s. strauchii (Schmidtler & Schmidtler 970, Pasmans et al. 2006). Our data show that water temperatures can be much lower in breeding N. s. barani . However, water tem- perature likely increases in the weeks after thaw, as sup- ported by data taken by us on an earlier occasion but lat- er in the year (see Pasmans et al. 2006), and will then be more favourable for larval development. The water quality parameters (Table 2) did not differ much from previously recorded values (see also Pasmans et al. 2006), only the levels of GH (general hardness) and KH (carbonate hardness) were lower in 2007, which was perhaps the result of melting ...