Åòòîëîã³ÿ Á3åðêó 12Â4èï. 2100 258 - 26

CALL FUNCTION AND VOCAL ACTIVITY IN THE SOUTHERN BALD AT A BREEDING SITE

Grzegorz Kopij

Abstract. Studies were carried out in a breeding colony at Welgelegen, eastern Free State, South Africa in 1994. Seven different calls in the Southern Bald Ibis were distinguished and their function has been determined: ‘clangor’, alarm, barking, copulation, snoring, greeting and begging. In the pre-laying phase, breeding and non- breeding pairs were equally vocal. Among breeding females were more (60.0 %) vocal than males (40.0 % of 402 calls recorded), while among non-breeding paired birds the reverse was true (males: 57.5 %, females: 42.5 %; n = 134 calls recorded). At the nest, breeding birds were more vocal during the incubation than during the pre-laying and nestling phases, while non-breeding paired birds are more vocal at the beginning of the breeding season than latter. During the day, breeding birds are more vocal in the morning (700–1000; 40.5 %), while non- breeding paired birds are more vocal around the noon (1000–1400; 50.6 %) and in the evening (1600–1800; 23.4 %). Key words: Southern Bald Ibis, calvus, South Africa, vocalization, vocal activity. Address: Department of Zoology & Ecology, Agricultural University of Wroc³aw, ul. Ko¿uchowska 5b, 51- 631 Wroc³aw, Poland.

Ôóíêöèè êðèêîâ è âîêàëüíàÿ àêòèâíîñòü ó ëûñîãî èáèñà â ìåñòàõ ãíåçäîâàíèÿ. - Ã. Êîïèé. - Áåðêóò. 13 (2). 2004. - Èññëåäîâàíèÿ ïðîâîäèëèñü íà îäíîé èç ãíåçäîâûõ êîëîíèé â Âåëãåëåãåíå íà âîñ- òîêå Îðàíæåâîãî Ñâîáîäíîãî Ãîñóäàðñòâà â ÞÀÐ â 1994 ã. Áûëî âûäåëåíî 7 ðàçëè÷íûõ êðèêîâ è îïðåäå- ëåíà èõ ôóíêöèÿ: òðåâîãà, êîïóëÿöèÿ, ïðèâåòñòâèå, âûïðàøèâàíèå è äð. Ïåðåä îòêëàäêîé ÿèö âîêàëüíàÿ àêòèâíîñòü ãíåçäÿùèõñÿ è íåãíåçäÿùèõñÿ ïòèö ïðèìåðíî îäèíàêîâà. Ñðåäè ãíåçäÿùèõñÿ ïòèö áîëåå àê- òèâíî âîêàëèçèðóþò ñàìêè (60,0 %), ÷åì ñàìöû (40,0 %, n = 402), ñðåäè íåãíåçäÿùèõñÿ – ñàìöû (57,5 %, ñàìêè: 42,5 %; n = 134). Íà ãíåçäå ãíåçäÿùèåñÿ ïòèöû áîëåå êðèêëèâû âî âðåìÿ íàñèæèâàíèÿ, ÷åì äî îòêëàäêè ÿèö èëè ïðè âûêàðìëèâàíèè ïòåíöîâ. Íåðàçìíîæàþùèåñÿ ïàðû áîëåå àêòèâíî âîêàëèçèðóþò â íà÷àëå ãíåçäîâîãî ñåçîíà, ÷åì ïîçæå. Íà ïðîòÿæåíèè äíÿ ãíåçäÿùèåñÿ ïòèöû áîëüøå êðè÷àò óòðîì (700– 1000; 40,5 %), íåãíåçäÿùèåñÿ – îêîëî ïîëóäíÿ (1000–1400; 50,6 %) è âå÷åðîì (1600–1800; 23,4 %).

INTRODUCTION monospecific colonies, not on trees but on sandstone cliffs. Unlike other members of the (Threskiornithinae) are a cosmopoli- order it is also not directly associated with tan ciconiifrom subfamily of 32 found wetlands and it inhabits mountain grasslands mainly in the tropics (Del Hoyo et al., 1992). and farmlands. It is silent while feeding, but In the Afrotropical region, there occur eight vocal in breeding sites. ibis species (Dowsett, Forbes-Watson, 1993) Behaviour of this species in breeding sites associated usually with lowland wetlands. has been thoroughly investigated in its strong- Most of these species are gregarious both while hold in the eastern Free State (Kopij, 1998b; feeding and at nesting sites. The extend of so- Kopij et al., 2000). Its breeding display, ago- cial tendency varies, however, from species to nistic, anti-predator, comfort and parental be- species. is strictly colonial, Ge- haviour were found to be highly developed and ronticus and are less so, and Bostri- complex, and it is often accompanied by spe- chia is actually a solitary breeder (Brown et cific vocalization (Kopij 1998a). Although, the al., 1982). Because of gregariuos habits, most Southern Bald Ibis behaviour is well documen- ibis species should be vocal, but they are in ted, little is known about vocalization in this fact rather silent as their vocal apparatus is not species. Brown et al. (1982) listed seven dif- well developed. ferent calls, but these calls are not fully de- Among ibises occurring in Africa, the scribed and their function is not always well Southern Bald Ibis (Geronticus calvus) is es- explicit. The purpose of this study was to pecially interesting. Unlike most other mem- analyse at breeding sites, the function of the bers of the order Ciconiiformes it breeds in Southern Bald Ibis calls, daily and seasonal

© G. Kopij, 2004 Âèï. 2. 2004.Call function and vocal activity in the Southern Bald Ibis 259 vocal activities between male and female, be- tions; the first one was occupied by a breeding tween parents and offspring and between non- pair, while the other one by a non-breeding breeding and breeding pairs. pair. Observations, using 10 x 50 binoculars and a Panasonic TTL 200 mm video camera, STUDY SITE were made from a shelter built on a rocky out- crop on the opposite cliff at a distance of 15 m Studies were carried out at a colony situ- from the first and 20 m from the second nest. ated in a gorge, 7 km north of Clarens in the The shelter was entered without any distur- eastern Free State (28°30' S, 28°20' E), South bance to the birds. Africa. The gorge is narrow (c. 10–20 m), but Observations at the two nests were stan- deep (c. 80 m), with a small stream flowing dardised and were carried out on a weekly basis through it. As the gorge is closed on three sides, from 21 July until 4 October 1994; i. e. 21 and the stream flowing into it forms a narrow wa- 27 July (pre-laying phase); 4, 11, 18, 25 and terfall. There is a small (c. 30 m2) but quite 30/31 August (incubation phase), 6/7, 13/14, deep (2 m) pool at the point where the gorge 20/21, 27/28 September and 4 October (nest- broadens. Further on the gorge is much ling phase). On 27 July and 4, 11 and 18 Au- broader, forming a valley vegetated with trees gust both nests were under detailed observa- (mainly Grewia occidentalis, Leucosidea tion. Since the nest of the non-breeding pair sericea, Populus tremula and Salix babylo- was occupied only occasionally after 30 Au- nica). The gorge is bordered on one side by gust, observations on it were stopped. From mountainous highveld grassland utilised as 21 July to 25 August, studies were conducted pastures for cattle and sheep, and on the other throughout the day (600–1800), whereas latter by cultivated fields with maize as the main on, observations in the morning (600–1200) and crop. A dam is situated 3 km north of the gorge. afternoon sessions (1200–1800) were carried out The Southern Bald Ibis colony was occu- on alternate days (vide Kopij et al., 2000). pied by 23 breeding and seven non-breeding Most call notes were kept in the form of pairs, and later in the season (after 5 Septem- time-scores (for each 15 minute period). There ber), seven immature birds remained in the is no sexual dimorphism in the Southern Bald colony. Five other nests, built on sandy rock Ibis. Sexes were distinguished in the nests by ledges, were located out of the gorge 100, 200, behaviour and by individual characters, e. g. 400 and 500 m away from the main colony. marks on their foreheads or cheeks. The nest under detailed observation was al- ready occupied by a pair on the first day of the RESULTS AND DISCUSSION study. The first egg was laid on 4 August, the second on 8 August and the third on 10 Au- Call function gust, while the first nestling hatched on 1 Sep- Seven different calls were distinguished in tember, the second on 3 September and the last this study: ‘clangor’, alarm, barking, copula- on 5 September. The youngest chick died at tion, snoring, greeting and begging. age 5 days and the next one at age 12 days; the The Clangor: ‘whee-okh, whee-okh, whee- oldest (when 35 days old) was killed by a Black okh ...’ A prelonged, flute-like call, somewhat Eagle (Aquila verreauxii) (Kopij, 1995). resonant, usually given by birds arriving or de- parting the breeding colony. This call most MATERIAL AND METHODS probably encourages other birds to leave the colony. Studies on the behaviour of the Southern The alarm call: ‘peeokh’. It sounds like a Bald Ibis were conducted at the Welgelegen short version of the clangor. At breeding site, colony during the breeding season, from 2.07 it was heard most often at the beginning of the until 4.10.1994 (Kopij et al., 2000). Two nests incubation phase (i. e. 11–18 August; 77 % of were under detailed week-to-week observa- all records of this call; Fig. 1). During the day, 260 G. Kopij Áåðêóò 13.

20 35 SEASONAL DAILY 30 15 25 20 10 15 10 PERCENTAGE 5 5 PERCENTAGE 0 0 1234 123456789101112 DAY TIME

DAILY 30 SEASONAL 20 25 20 15 15 10 10 5 PERCENTAGE PERCENTAGE 5 0 6H 7H 8H 9H 10H 11H 12H 13H 14H 15H 16H 17H 0 TIME 123456789101112 DAY Fig. 2. Seasonal and daily vocal activity of non- breeding Southern Bald Ibises at a nesting site. Fig. 1. Seasonal and daily vocal activity of 1 – 27 July, 2 – 4 August, 3 – 11 August, 4 – breeding Southern Bald Ibises at a nesting site. 18 August. Black columns indicate adult birds, white – chicks; 1 – 21 July, 2 – 27 July, 3 – 4 August, 4 – 11 August, 5 – 18 August, 6 – 25 August, with growls and moans was also distinguished 7 – 30/31 August, 8 – 6/7 September, 9 – 13/ in the invitation call. The so called ‘croop’ call 14 September, 10 – 20/21 September, 11 – 27/ of the (Geronticus eremita) 28 September, 12 – 4 October (1–2: pre-lay- is probably homologous to this call. Pegoraro ing phase, 3–7: incubation phase, 8–12: nest- and Foger (1995) studied intraspecific varia- ling phase). tion in this call and evidenced sexual and indi- vidual distinctiveness of this call indicating its function as an expression of motivational the call was recorded mainly between 1000 and stages of the signaller. 1300 (61 %) and between 1600 and 1800 (27 % The copulation call: ‘ekekekekekekek...’ It of all alarm calls recorded). The call was ut- is a prelonged version of the barking call, com- tered to warn other birds about a potential posed of dozen or so quick repetitions of the predator, including human, and during com- ‘ek’ syllable. It is uttered by female, 3–6 sec- munal mobbing of the Black Eagle (Kopij, onds after being mounted by male during the 1995). copulation. The barking call: ‘ek-ek-ek...’ Heard only The snoring call. It consists of growls and at nesting sites, and mainly during the nestling moans. Uttered during the back-biting cere- phase (Fig. 1 and 2). It probably strengthen mony and other agonistic interaction (cf. Kopij, the bond between parents and between parents 1998a). This call was also recorded in older and their chicks, as the call is most often ut- chicks during fighting with younger siblings. tered as a reaction for chick’s call and during The greeting call; a mixture of different preening of adult birds (Table). Different num- calls, with growls and moans being most often ber of syllables recorded in the call may indi- heard. This call is delivered during the invita- cate different motivational stages of the sig- tion ceremony (cf. Kopij, 1998a) by the nallers (Table). The male and female differ which has remained in the nest; the arriving slightly in this regard (Table). This call mixed bird remained silent during this ceremony. Âèï. 2. 2004.Call function and vocal activity in the Southern Bald Ibis 261

Begging call: a long persistent The relationship between the number of syllables in the chirrup ‘shreeeee’ uttered by chicks Southern Bald Ibis barking call and its function in discomfort situations, e. g. hun- Ñâÿçü ìåæäó êîëè÷åñòâîì ñëîãîâ â ëàþùåì êðèêå ger, cold, heat. ëûñîãî èáèñà è åãî ôóíêöèåé No mechanical sounds, e. g. bill- clapping, rattle or clatter were re- Situation/sex Mean Range N % corded both in adult birds and Response to chick’s call 4.2 1 – 10 10 8.6 chicks. According to Brown et al. Preening 3.4 1 – 8 20 17.2 (1982) bill-snapping is performed Resting 3.3 1 – 7 66 56.9 by both sexes during the copulation. Other situations 2.8 1 – 5 20 17.2 Vocal activity Male 3.4 1 – 10 61 52.6 In the pre-laying phase, breed- Female 3.0 1 – 8 55 47.4 ing and non-breeding pairs were equally vocal; 104 calls were recorded for a ments in the major textbooks on African birds breeding pair during the 16 hours of observa- (Brown et al., 1982; Del Hoyo et al., 1992; tions (i. e. 6.5 calls per hour) were uttered by a Maclean, 1993) that the Southern Bald Ibis is, non-breeding pair. as for an ibis species, very vocal at breeding Among breeding birds females were more colony throughout the breeding season. This (60.0 %) vocal than males (40.0 % of 402 calls could have developed under conditions where recorded), while among non-breeding paired communally breeding birds had problems in birds the reverse was true (males: 57.5 %, fe- visual contacts, as in some caves or hanging males: 42.5 %; n = 134 calls recorded). Breed- rock cliffs. Probable strong pair-bond could ing females are more involved in incubation have also facilitated birds to be vocally active. and brooding, spending more time in the nest than the male (Kopij et al., 2000), while non- REFERENCES breeding male and female spend the same Brown L.H., Urban E.K., Newman K. (1982): The Birds amount of time in the nest. of Africa. Vol. 1. London: Academic Press. The vocal activity of parents and chicks Del Hoyo J., Elliot A., Sargatal J. (1992): Handbook of was held on similar level throughout the nest- the Birds of the World. Vol. 1. Barcelona: Lynx ling phase. During 54 hours of observations, Edicions. Dowsett R.J., Forbes-Watson A.D. (1993): Checklist of 124 calls of single parent and 243 calls of two birds of the Afrotropical and Malgasy regions. Liege chicks were recorded (Fig. 1). (Belgium): Tauraco Press. At the nest, breeding birds were more vo- Kopij G. (1995): Black Eagle Aquila verreauxii predation on Southern Bald Ibis Geronticus calvus nestlings cal during the incubation than during the pre- in South Africa. - J. Afr. Raptor Biology. 10 (1): 37. laying and nestling phases, being especially Kopij G. (1998a): Behavioural patterns in the Southern vocally active during the egg-laying and early Bald Ibis Geronticus calvus at breeding sites. - incubation phases (Fig. 1). At these stages the Vogelwarte. 39: 248-263. Kopij G. (1998b): Breeding ecology of the Southern Bald vocalization may strengthen the pair-bond. Ibis Geronticus calvus in the Free State, South Africa. Non-breeding paired birds are more vocal at - Acta. Orn. 33: 99-111. the beginning of the breeding season than latter. Kopij G., Kok O.B., Nuttall R.J. (2000): Breeding cycle of the Southern Bald Ibis Geronticus calvus. - During the day, breeding birds are more Ostrich. 71: 393-399. vocal in the morning (700–1000; 40.5 %; Fig. Maclean G.L. (1993): Robert’s birds of southern Africa. 1), while non-breeding paired birds are more Cape Town: John Voelcker Bird Book Fund. vocal around the noon (1000–1400; 50.6 %) and Pegoraro K., Fager M. (1995): Die ‘Chrup’-Rufe des Waldrapps Geronticus eremita: ihre verschiedenen 00 00 in the evening (16 –18 ; 23.4 %; Fig. 2). Funktionen in einem komplexen Sozialsystem. - J. Chicks are more vocal in mid-day (Fig. 1). Orn. 136: 243-252. The present studies confirm general state-