Author/Editor		Sackl, Peter
Title		Form and function of aerial courtship displays in black storkes Ciconia nigra
Translated title		Oblika in funkcija dvorjenja črnih štorkelj Ciconia nigra v zraku
Type		članek
Source		Acrocephalus
Vol. and No.		Letnik 21, št. 102-103
Publication year		2000
Volume		str. 223-9
Language		eng
Abstract		Hitherto unknown aerial courtship displays of Black Storks Ciconia nigra recorded for the most part during population surveys in northern and eastern Austria between 1979-1991 are described. Aerial displays were seen mainly during early stages of the breeding cycle in April till mid-May (Fig. 1). They are characterized by mates soaring tight together in a highly synchronized manner above the nest-site or in other parts of the home range (Parallel Soaring). Additionally, melodious Hight calls are given by both partners and the white undertail-coverts are widely spread. Occasionally soaring birds were seen whiffling or performing simultaneous darting flights (Fig. 3). According to (1) the regular participation of both breeding partners, (2) their regular performance around nest sites and/or within home ranges, (3) their largely restricted occurrence during early stages of the breeding cycle as well as (4) by their specific pattern of stereotyped and elaborated behavioural elements (Parallel Soaring, Displaying the Undertail-Coverts, Flight Calls, Whiffling and Darting Flights) ceremonial Aights in Black Storks may generally operate as highly ritualised courtship flights. Thus, analogous to aerial displays in other large forest-living birds - like in many raptors - they may help in pointing out nest-sites to potential mates, stimulate pair formation and assist in spacing by discouraging other birds from settling close. The highly elaborated courtship Hights in Black Storks seem to be unique within the "typical" storks of the tribe Ciconiini and coincide with the solitary nesting habit of the species within the closed canopies of heavily wooded areas.
Summary		Avtor obravnava do danes neznano obliko dvorjenja črnih štorkelj Ciconia ciconia v zraku, večinoma zabeleženo med popisovanjem ptičjih populacij v severni in vzhodni Avstriji med letoma 1979 in 1991. Dvorjenja v zraku so bila opazovana predvsem v zgodnjih fazah gnezditvenega obdobja, in sicer od aprila do sredine maja (sl. 1). Glavna značilnost dvorjenja črne štorklje je naglo in nadvse sinhrono dviganje para proti nebu tesno skupaj nad gnezdiščem ali drugod v njunem domačem okoliju (vzporedno dviganje). Oba partnerja hkrati spuščata melodične glasove in razgaljata podrepne krovce. Tu in tam so proti nebu dvigajoči se pari sunkovito pihali ali pa so simultano pikirali proti tlom (sl. 3). Glede na (1) redno sodelovanje obeh gnezdečih partnerjev, (2) njihovo stalno nastopanje nad gnezdiščem in/ali domačim okolišem, (3) njihovo v veliki meri zmanjšano pojavljanje v zgodnjih fazah njihovega gnezditvenega obdobja in (4) tudi glede na značilni vzorec njihovih stereotipnih in dovršenih vedenjskih vzorcev (vzporedno dviganje, razkazovanje podrepnih krovcev, oglašanje v zraku, sunkovito pihanje in pikiranje) se zdi, da so obredni poleti črnih štorkelj visoko ritualizirani snubitveni leti. Analogno z razkazovanjem drugih velikih gozdnih ptic v zraku - na primer mnogih plenilcev - morebiti pomagajo pri sporočanju morebitnim partnerjem, da je tu gnezdišče, stimulirajo oblikovanje parov in pomagajo pri razporejanju parov z odganjanjem tekmecev. Izredno dovršeni snubitveni leti črnih štorkelj se zdijo enkratni med "tipičnimi" štorkljami iz plemena Ciconiini in so povsem v skladu s solitarnimi gnezditvenimi navadami te ptičje vrste znotraj s krošnjami zaprtih in gostih gozdnatih območij.
Descriptors		BIRDS COURTSHIP TIME FACTORS BEHAVIOR, ANIMAL ECOSYSTEM