摘要:

From 1981 to 1988 the wintering wildfowl population in the valley of the Ticino River varied from a minimum of 6 100 individuals in 1988 to a maximum of 20 910 individuals in 1982. Seventeen species were recorded; the mallard(Anas platyrhynchos)was the most common bird and on average represented 81.1% of the total population. Most of the waterbirds were observed in oxbow lakes, and these areas were positively selected by all species. Canals and streams were preferred by ducks. The river was avoided by all species, and reservoirs were only used by teals (Anas crecca)and, to a lesser extent, by mallards. Riparian vegetation cover and disturbance were the main factors affecting the distribution of water‐birds. Most of the wildfowl used the wetlands only for roosting. A reduction in the movement of birds from roosting to feeding sites (mainly maize and wheat stubbles), and hence a reduction in the mortality caused by hunting, could be achieved by management practices aimed at increasing aquatic vegetation in the wetlands.

ISSN:0373-4137    

DOI:10.1080/11250008909355625

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Following the recent discovery of seven new species, ten specific taxa are now recognized within the genusBacillus:1.B. rossius;2.B. grandii;3.B. whitei;4.B. lynceorum;5.B. atticus;6.B. diplocarius;7.B. carius;8.B. rhodius;9.B. cyprius;10.B. creticus.Furthermore, eight subspecies have been defined withinB. rossius.The distribution and the ecology of the species are summarized. On the basis of ootaxonomy, karyology, electrophoretic allozyme analysis and vitellin comparisons, the phyletic relationships among taxa within the genus are suggested, with particular emphasis on the natural thely‐tokous hybrids,B. whiteidiploid and the triploidB. lynceorum.The main evolutionary mechanisms at work here appear to be: interspecific hybridization, polyploidy, chromosome repatterning and the switch to parthenogenetic reproduction. Gradual genetic differentiation has produced subspecific taxa inB. rossius.

ISSN:0373-4137    

DOI:10.1080/11250008909355626

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Copidognathus dactyloporusn. sp. from plain springs near Verona (northern Italy) is described. This is the first report of a freshwater species of the genusCopidognathusin Italy.

ISSN:0373-4137    

DOI:10.1080/11250008909355627

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Anomalohalacarus singularis,a new species of marine Halacaridae from a sandy bottom near Leghorn (Tuscan coast, Italy) is described. Characteristic features of the species are an undivided anterior epimeral plate and in the male a large number of perigenital setae.

ISSN:0373-4137    

DOI:10.1080/11250008909355628

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0373-4137    

DOI:10.1080/11250008909355629

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

ISSN:0373-4137    

DOI:10.1080/11250008909355614

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor