Acta zoologica cracoviensia, 46(2): 97-195, Kraków, 30 June, 2003 Nesting of the Acrocephalus warblers Zygmunt BOCHEÑSKI and Piotr KUŒNIERCZYK Received: 14 Feb 2003 Accepted: 26 May 2003 BOCHEÑSKI Z., KUŒNIERCZYK P. 2003. Nesting of the Acrocephalus warblers. Acta zoo- logica cracoviensia, 46(2): 97-195. Abstract. The paper contains data concerning nest sites, material, construction, shape, and sizes in the majority of Acrocephalus species. The descriptions are based on field studies, museum specimens, and literature. The system proposed by CLEMENTS (2000) including 36 species in the genus Acrocephalus has been adopted. Similarities and differ- ences in nesting of 32 species and four subspecies are studied in the last chapter on the ba- sis of 38 characters assembled in Table XLI. They do not always reflect systematic relations of warblers within the genus Acrocephalus on the basis of molecular data. Key words: genus Acrocephalus, nest site, nest material, nest construction, nest shape, nest sizes. Z. BOCHEÑSKI (corresponding author), Institute of Systematics and Evolution of Ani- mals, P.Ac.Sc., 31-016 Kraków, S³awkowska 17, Poland. E-mail: [email protected] P. KUŒNIERCZYK, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, P. Ac.Sc., 53-114 Wroc³aw, Rudolfa Weigla 12, Poland. I. INTRODUCTION The genus Acrocephalus seems not to be defined unequivocally. From time to time it resembles a “witch’s sack”, to which various ornithologists place, according to their predilections, various species of Sylviinae, apart of a few, which are always in this genus. Those additional species are in- cluded in other genera, set up especially for them by other researchers . This causes serious diver- gences in the numbers of species, which are also enlarged by the differences in treatment of particular forms at the species/subspecies level. For instance, WILLIAMSON (1960) includes 13 spe- cies in the genus Acrocephalus,CLEMENTS (1974) – 16, WOLTERS (1980) also 16 (but a part of them only is listed by CLEMENTS 1974). According to MORONY et al. (1975) and COURTNEY-HAINES (1991) there are 27 species, and according to HOWARD and MOORE (1991) – 28; they also list in the genus Acrocephalus species which other authors include in the genera Lusciniola, Calamodus, Conopoderax, Calamocichla (part) and Phragmaticola.SIBLEY and MONROE (1990) mention 32 species, treating several subspecies as valid species. None of the above mentioned authors write about Acrocephalus sechellensis and A. rodericanus, listed by them in Bebrornis.KOMDEUR (1996) and SIBLEY (1996), however treat them as them as real acrocephalines which was accepted by CLEMENTS (2000), who in the genus Acrocephalus listed altogether 36 distinct species. The present paper is not strictly systematic, hence, as a starting point, the authors have generally adopted the system and species English names proposed by CLEMENTS (2000). They know that treating particular forms, especially controversial ones, may not be approved by all researches. Z. BOCHEÑSKI,P.KUŒNIERCZYK 98 They hope, however, that the materials presented here may, at least in part, explain the above- mentioned controversies and help a little to set in order the systematics of the genus. According to MAYR (1958) and GREENWOOD (1997), the elements of animal behavior, espe- cially these connected with reproduction, are diagnostic characters equal to morphological and mo- lecular characters. One of them are innate methods of nest formation in birds. This was documented by experiments of PROMPTOV (1945) and stereotype activity of nest cup formation performed by young birds observed by GOODWIN (1954), DILGER (1956) and the HEINROTHS (1965). First of all the authors describe here the nesting of European species, because for them we ob- tained the largest numbers of nests to study. As a background they gathered as much data as possible on the nests of extra-European species, studying specimens in several collections. However, in many cases they failed to collect data because the species grouped in the genus Acrocephalus in- habit huge territory (the Palaearctic, Ethiopian, Indo-Malayan, Oriental, Australian regions and se- lected islands of the Pacific, Indian and Atlantic Oceans – Fig. 1), and many endemic species are not represented in the collections. They were not able to study in person the nests of 18 species listed by CLEMENTS (2000) in the genus Acrocephalus. They are listed below in alphabetical order (together with distribution data): aequinoctialis (Christmas and Fanning Islands), atyphus (Tuamotu Archi- pelago), baeticatus (E & S Africa) brevipennis (Cape Verde Islands), caffer (Society Islands), gra- cilirostris (Subsaharan Africa), griseldis (S Iraq), kerearako (Cook Islands), luscinius (Mariana Islands), orinus (N India – known from one skin only), rehsei (Nauru Islans), rimitarae (Tubuai Is- lands: Rimitara), rodericanus (Rodrigues Island), rufescens (Subsaharan Africa), sechellensis (Seyshelles Islands), sorgophilus (NE China – according to PARKER &HARRISON 1963, Fig. 1. General limits of the breeding distribution of all species included by CLEMENTS (2000) in the genus Acrocephalus, compiled after ALI &RIPLEY (1973), BAKER (1951), CHENG (1976), CRAMP (1992), FLINT et al. (1968), HARRISON (1982), KOVSHAR (1972), NECHAEV &FUJIMAKI (1994), PTUSHENKO (1954), SMITHIES (1968), SONOBE (1982), URBAN et al. (1997). Nesting of the Acrocephalus warblers 99 COURTNEY-HAINES 1991 and SIBLEY 1996 its breeding biology is unknown), taiti (Henderson Is- land) and vaughani (Pitcairn Island). An attempt was made to gather descriptions of their nests scat- tered in ornithological literature. In many cases this was successful, but those descriptions are not always satisfactory. Finally, the authors were unable to find any data concerning the nests of five species (i.e. griseldis, orinus, rodericanus, sorgophilus and tangorum). Many persons helped in gathering the materials for the present paper. Dr E. N. KUROCHKIN,Dr O. LANGRAND, Prof. Dr R. MACKOWICZ, the late Capt. J. H. MACNEILE,MrT.OLEŒ,DrT.TOMEK, and Prof. Dr J. WITKOWSKI collected the nests or the data for nest record cards being in the authors’ charge. Prof. Dr K. HUDEC permitted the studying of nest record cards stored at the Institute of Ver- tebrate Biology, Czech Rep. Ac. Sc. in Brno. The late Prof. Dr A. P. KUZYAKIN and Dr V. V. LEONOVICH permitted examination of the nests at their private collections. Dr P. DEVILLERS (Brus- sels), Prof. Dr V. E. FLINT (Moscow), Dr C. HARRISON (Tring), Dr G. F. MEES (Leiden) gave access to specimens in the collections being in their charge. Dr Ph. HORTON (Adelaide) lent two nests of the Australian Reed Warbler and took measurements of another two nests. Prof. Dr R. MACKOWICZ, Mrs Z. MALCHER and Mrs J. PA£KA helped in gathering the literature. Ms K. OCHMAN M.Sc. helped with statistics, Mr M. FINIK made two drawings based on photographs, Mrs M. MATYJASZKIEWICZ M.Sc. prepared computer version of drawings, dr Z. M. BOCHEÑSKI prepared computer version of photographs (original and reproduced), Mr Ch. PAYNE of Oxford University Press, Mrs A. BIELSKAS of the American Museum of Natural History Library, Mrs J. C. LUCENTE of “The Wilson Bulletin”, Prof, dr Ch. FEARE of the “Bulletin of the British Ornithologist’s Club”, and Dr J. P. DEJONGHE of “Alauda”, sent the permissions for reproducing figures (photographs and drawing) published in journals represented by them. We owe our heartfelt gratitude to them all. We are also greately indebted to Prof. Dr A. DYRCZ and Dr B. LEISLER for their reviews of the manuscript. II. MATERIAL AND METHODS The results of field observations were noted on nest record cards. The data consist of the nest measurements, nest site, material used for building, some characters of nest construction; sketches of the nest sites are often presented. Photographic documentation is provided for many nests. In the case of the Marsh Warbler and Sedge Warbler also used were the data from nest record cards col- lected before 1967 from the territory of former Czechoslovakia and stored at the Institute of Verte- brate Biology in Brno. Most probably they constitute a part of data used then by HUDEC (1983). The nests stored in several museums as well as in private collections were also studied. Original descriptions of nests, made in the field or in collections, are completed by data taken from literature. This especially concerns the species of very vide distribution, if studied specimens come from a part of their breeding areas. The places from which the described nests come are shown on maps, on the background of general limits of the breeding distribution of given species; non- inhabited areas within those limits are not indicated. The finding places of specimens described in fields or in collections are indicated by black dots. Descriptions from literature concerning nests from large areas are indicated with empty asterisks. The scales of maps and their projections are not unified. In describing the nest site, the species of plant (or its kind only), number of stems (or branches), and height above water or ground, were taken into account. The nest sites of the Acrocephalus war- blers are diversified, therefore a few general types of them were established. They are shown in Fig. 2. Unfortunately, the labels of nests housed in collections do not always contain sufficient data con- cerning their sites. The material used for the building of nests is described with various accuracy: in the field, de- scribing the nests