Colonisation and diversification of the blue tits (Parus caeruleus teneriffae-group) in the Canary Islands.

The blue tit (Parus caeruleus teneriffae group) is proposed to have colonised the Canary Islands from North Africa according to an east-to-west stepping stone model, and today, the species group is divided into four subspecies, differing in morphological, acoustic, and ecological characters. This colonisation hypothesis was tested and the population structure between and within the islands studied using mitochondrial DNA sequences of the non-coding and relatively fast evolving control region. Our results suggest that one of the central islands, Tenerife, was colonised first and the other islands from there. Three of the presently recognised four subspecies are monophyletic, exception being the subspecies teneriffae, which consists of two monophyletic groups, the one including birds of Tenerife and La Gomera and the other birds of Gran Canaria. The Gran Canarian birds are well differentiated from birds of the other islands and should be given a subspecies status. In addition, the teneriffae subspecies group is clearly distinct from the European caeruleus group, and therefore the blue tit assemblage should be divided into two species.

Habitat deterioration and efficiency of antipredator strategy in a meadow-breeding wader, Temminck's stint (Calidris temminckii).

Many populations of waders breeding on open shores and shores with short vegetation especially on the Baltic coasts have recently become endangered. The declines have taken place simultaneously with human-induced loss and deterioration of habitats due to eutrophication and overgrowth. To investigate mechanisms by which habitat changes could affect breeding success and ultimately population dynamics, we studied an endangered coastal population of Temminck's stint. We hypothesized that the rate of nest predation has become higher because the nest defence strategy (early detection of predator and early departure from the nest), which originally evolved in open habitats, is less effective on shores with reduced visibility. As predicted, nests survived better on wide than on narrow shores. Predation made a major contribution to this trend, although successful and predated nests did not differ in concealment at a microhabitat scale. The better the visibility from the nest, the longer was the flushing distance, but only in response to alarm calls or behaviour of other species, not when they were absent. Temminck's stints seem to obtain information about an approaching predator visually from sentinels. Therefore, it is essential that there is at least moderate visibility around the nest. We conclude that habitat characteristics - visibility from the nest and sentinel birds - affect the effectiveness of the nest defence strategy of Temminck's stint. These should be taken into account when seeking causes and mechanisms for declines of Temminck's stint and other waders of open and shortly vegetated shores.

Comparison of nitrazepam 5 mg with triazolam 0.5 mg in young psychiatric insomniac inpatients. Double-blind single night cross-over study.

Sixty young male patients with insomniac disorders were treated with nitrazepam 5 mg or triazolam 0.5 mg in a double-blind single night cross-over study. The results were favourable for triazolam in all the sleep parameters assessed. The significance of an hypnotic with a short life and its use in clinical practice is discussed.