PwG OTOP - Południowowielkopolska Grupa OTOP
Transcription
PwG OTOP - Południowowielkopolska Grupa OTOP
Tryjanowski P., Sparks T.H. & Jerzak L. (eds.) The White Stork in Poland: studies in biology, ecology and conservation Bogucki Wydawnictwo Naukowe, Poznań 2006 “Close to Storks” – a project of on-line monitoring of the White Stork Ciconia ciconia nest and potential use of on-line monitoring in education and research Paweł T. Dolata South Wielkopolska Group of the Polish Society for the Protection of Birds, Wrocławska 60A/7, PL-63-400 Ostrów Wielkopolski, Poland, e-mail: [email protected] ABSTRACT: This paper describes the on-line monitoring project “Close to Storks”, carried out by the South Wielkopolska Group of the Polish Society for the Protection of Birds. The monitored nest of the White Stork Ciconia ciconia is situated in the village of Przygodzice, near the town of Ostrów Wielkopolski (South-Western Poland). The main aim of the project was popularisation of ecological issues. Over the five months of the 2006 breeding season more than 660,000 people from 84 countries visited the website www.bociany.ec.pl with the image of the nest. Polish media were also keenly interested in the project. From the research perspective, camera monitoring provides a good opportunity to collect breeding biology and ecology data, which is difficult (or even impossible) to obtain by standard methods. Preliminary results collected in 2006 are presented, including the first precise observation of egg laying by White Stork in Poland and a clear case of parental infanticide. Intervals between successive eggs laid by the female were about 45–48 hours. The female laid eggs at night. Potential applications and problems entailed by camera monitoring are discussed. Using this method should involve full video-recording of subjects and collaboration with ornithologists. KEY WORDS: Ciconia ciconia, ecological education, on-line monitoring, breeding biology, breeding ecology, parental infanticide, egg laying Introduction The White Stork Ciconia ciconia is one of the most popular bird species in Poland (Sokołowski 1958, Lewandowski & Radkiewicz 1991, Dolata 2006) and for this reason it seems to be an appropriate species for the purpose of increasing interest in birds and nature protection problems in Poland. 438 Paweł T. Dolata Although the White Stork is also one of the most extensively studied bird in Poland, some details of its biology and ecology are unknown or unclear (e.g. Ptaszyk 1998, Antczak & Dolata 2006, Kania 2006, Profus 2006). Between the years 1971–2000, according to the Wildlife & Ecology Studies Worldwide, 737 ornithological papers about the White Stork were published in Poland (Kopij 2005), but a large majority of them concerned only population size, distribution and breeding success. There are only a few Polish papers that focus on other aspects of the White Stork’s breeding biology (e.g. Mrugasiewicz 1972, Profus 1986, 1991, 2006, Radkiewicz 1992). Some data, such as that concerning egg laying can be collected accurately by monitoring nests with a camera, like it was done in Germany (Hoffmüller 2001). This paper reports the first results obtained in the “Close to Storks” on-line project, led by the South Wielkopolska Group of the Polish Society for the Protection of Birds (Południowielkopolska Grupa Ogólnopolskiego Towarzystwa Ochrony Ptaków, PwG OTOP), which aimed to be an example of its scientific usefulness. Methods th On the 24 of March, 2006, before storks returned to their breeding grounds, a small digital TV-camera was installed on a chimney 1.5 m above White Stork nest. The nest is located in the village of Przygodzice (51°35' N, 17°49' E) near Ostrów Wielkopolski (the Wielkopolska region), on the edge of the Barycz River Valley. The area is part of the Barycz Valley Landscape Park and of a Special Protected Area of the Natura 2000 network of the European Union. The Barycz River Valley was the feeding area for the observed pair. Additionally, while nestlings were ringed on the 19th of June, a microphone was installed by the nest (Phot. 1). The camera was fixed on an arm, which did not hamper the birds with landing or taking off from the nest (Fig. 1). Throughout the entire breeding season the birds’ behaviour did not appear to be affected by the equipment (see Phots. 1 & 2). The camera image (Phot. 2), refreshed every 2–5 seconds, and the sound from the available on-line initially on the PwG OTOP website www.pwg.otop.org.pl and later on the specially created website www.bociany.ec.pl, and also as a continuous image (streaming) via ITTV Interactive Television. As the camera had the infra-red function, the storks could be tracked also at night. Details of the storks’ activity in the nest were recorded from the camera on-line image by: – four project members (Marcin Rachel, Eva Stets-Vithoulka, Sv tlana Vránová and author); – volunteer internauts who responded to an invitation to cooperation placed on the website, which outlined the aim and importance of observations and reports of the page viewers. The website enjoyed great popularity, being visited a few thousands times a day (up to 12,500). Therefore, it seemed advantageous to take the opportunity and invite visitors to collaboration. Support of these voluntary observers was important because long time observation of the nest was difficult to carry out by one or two observers. “Close to Storks” – a project of on-line monitoring of the White Stork nest 439 Phot. 1. The monitored nest with one-month nestlings, the microphone and the camera, th 19 June 2006. The Barycz River Valley in the background. Photo: Paweł T. Dolata 440 Paweł T. Dolata th Phot. 2. Screenshot of the monitored nest with displaying adults and eggs, 19 April 2006. Photo: Marcin Rachel Educational aspect During the five months of the 2006 breeding season (April–August) more than 660,000 people from 84 countries visited the website www.bociany.ec.pl, where the camera image of the nest was transferred, which made up nearly 1,300,000 visits. Various Polish media were also greatly interested in the project. More than 100 articles, notes or news broadcasts concerning the project were published in popular TV and radio channels, on websites, and in national as well as regional newspapers. The 1st Meeting “Close to Storks” in Przygodzice, which took place between 22–23 July 2006, was part of the project and was attended by approximately 70 participants. Feedback from internauts such as e-mails to the organizers of the project, opinions in the guest book on the website and a discussion forum indicated that the project “opened the eyes of ordinary people” for the birds and nature (majority of which were not birdwatchers or nature-lovers). Initial research results The initial results are given in Table 1. First, short visits of the monitored nest were done by not the same birds which occupied this nest for breeding season – on 28th “Close to Storks” – a project of on-line monitoring of the White Stork nest 441 Table 1. Selected data concerning the on-line monitored White Stork nest in Przygodzice, in 2006 Date Hours Short visits of the first White Storks at the nest Observed event 28.03 05.04 14.10 12.20 Nest occupied by a pair 08.04 13.13 First copulation st 1 egg laid 08.04 14.06 14.04 00.30–01.26 2nd egg laid 15.04 21.51–22.18 3rd egg laid 17.04 21.31–23.01 4th egg laid 19.04 20.01–20.14 5th egg laid 21.04 21.15 First documented event of alternate incubation 24.04 st 1 nestling hatched nd 18.05 The first change-over photographed, later change-over observed frequently afterwards 02.10–04.49 2 nestling hatched 18.05 09.30–11.30 3rd nestling hatched 19.05 before 04.47 4th nestling hatched 21.05 before 04.54 5 nestling hatched 22.05 16.42–17.13 One nestling disappeared from the nest 29.05 A living chick struck by a parent with its bill and thrown out of the nest 30.05 First fledged young 22.07 th Last night with all three young in the nest 09/10.08 First night without any stork in the nest 16/17.08 Last nights with one stork in the nest 17/18.08 18/19.08 Nest without birds since 19.08 Notes each visit lasted only a few minutes During a storm, probably pushed out by the wind (transmission error – no view from the camera) 13.08 The smallest nestling of the four, moving only slightly from the morning onwards, but alive in the moment of attack (observer via www: M. Bociański); found dead on the ground (T. Wojtasik) 15.07, 15.07 Probably frightened by a and 15.09 “stork-lover” who came too close to the nest and waved his hands to the camera Last stay of all the three in the nest Age of the bird not known 442 Paweł T. Dolata March it was with no doubt the bird which the same day started occupy another nest in Przygodzice. For egg laying and nestling hatching two times are given: the last observation before a new egg or nestling appeared and their first observation (e.g. on the 14th of April the last observation of the nest without eggs was at 00.30 and the first observation of an egg was at 01.30, when the female stood up). The female laid the first egg on the 7th day after arrival to the nest and the first copulation. The next 4 eggs were recorded at about 45, 48-, 45- and 48-hour intervals, respectively. The female was laying the eggs at night or in the evening (as was the case with the fifth egg). Since April 24th it was frequently recorded that the parents incubated the eggs alternately. With the presumption that three first hatched nestlings survived to fledging, based on general breeding ecology of the species (Profus 2006) and small body size of disappeared and killed chick, they first successful flights was done on 66th, 66th th and 67 day of life, respectively. Even flying during the days, they roosted on the nest regularly 19–25 consecutive nights (Table 1). A wider report of behavioural data collected in the project will be prepared by Sv tlana Vránová. Discussion Observed cases of early spring, short visits of birds which not stayed here for breeding season agree with data of Wuczyński (2005), that such cases are common. First arrivals of storks on the nest are such important event for the village people (as “sign of spring”) that it stayed in their memory, questionnaires or notes and are reported to the scientist as occupations of the nests – it may be source of important error in such data (see also Mrugasiewicz 1972). Clear instructions must be included in the inquiries or detailed interview must be done by researches to avoid such errors. The observed pair occupied the nest in the peak of the arrival time typical of the White Storks in Poland (Profus 1991, 2006, Radkiewicz 1992, Ptaszyk 1994). Time from the arrival of the second bird (occupation of the nest by the pair) to the first egg laying was also typical. In the breeding colony in Kłopot and in adjacent areas (W Poland) the first egg was laid 1–9 days (in one case 11 days) after the arrival of the second partner on the nest, and in 60.6% of the cases 3–4 days (Radkiewicz 1992) and in Upper Silesia (S Poland) the commencement of breeding occur in the average 10±0.82 days (SE) after the arrival of the second partner on the nest (N = 9, Profus 2006). Time of egg laying in the monitored pair was relatively early. In other studies (all of them were carried out in South-Western Poland, as in the case of the monitored nest, but most of them had a more southern location) females began laying eggs later: in the district of Milicz, between 1959–1968 less than 10% females started laying before April 15th; between 1973–1978 in Upper Silesia the average laying date was the 30th of April (Profus 1991) and in the province of Legnica in 1987 the first egg was laid between the 15th of April and the 4th of May (K. Kujawa, after Profus 1991). Data from studied nest are similar to the new data from Upper Silesia: during the period 1992–2002 the most intensive egg lay- “Close to Storks” – a project of on-line monitoring of the White Stork nest 443 ing (about 60% of pairs) occurred between 11th and 25th April and during the period 1990–2002 the average date of laying the first egg was 20th April (Profus 2006). Such earlier laying date of the monitored pair could be linked to a generally earlier laying date observed in the White Stork in the recent years (Ptaszyk et al. 2003, Profus 2006). Before the project was started, the most accurate data about the laying date of the White Stork in Poland was established by means of direct nest controls carried out every second day (Radkiewicz 1992). Less accurate data (up to one week or 4–6 days) was obtained by means of water tests (Majewski 1980) performed during a control of a nest (Profus 1991, 2006). Laying date was also estimated from the time of fledging, basing on a much smaller sample of multiple (we do not know how frequent) direct controls of 39 nests (Mrugasiewicz 1972). Such methods are sufficient to provide a general view of the breeding ecology of the species but they do not allow to obtain as precise data as it is possible with a camera. Sokołowski (1958) and Makatsch (1974) report that female White Storks laid eggs at 48-hour intervals. A more detailed study conducted by Radkiewicz (1992) revealed some variation in the laying interval: most of the eggs were laid at two-day intervals but some of them at one- or three- day intervals (19.4% and 0.9%, respectively). We should bear in mind that the study method classified an egg laid 15 minutes after control as an egg laid after a one-day interval. Also, a review of the Western Palaearctic literature published by Cramp (1998) reports that “eggs are laid at intervals ranging from 1 to 4 days, most typically 2”. One of the problems during the observation was that the precise laying time was impossible to pinpoint as most of the time the eggs were obstructed by the incubating female, especially in the second stage of the laying period. The number of eggs could be established only when the adult stood up. Therefore, in Table 1 two times are given for each egg: the last moment without the egg while nest bottom could be seen and the first time when the egg was observed. We noted an incidence of a chick being thrown out by a parent. Before this took place, several observers reported on the chick’s condition; however, only two of them noticed the actual moment of rejection of alive bird (M. Bociański and one anonymous observer from St Petersburg). This clearly shows that a flaw in this project was that the camera image was not recorded continuously. Even participation of more observers cannot substitute for systematic, continuous recording of the camera image and it should be crucial in on-line monitoring projects. Parental infanticide, which took place probably in the 9th or 10th day of the chick’s life (assuming that the chick, which was the smallest of the four, hatched as the fourth or fifth) occurred at a typical age. In Spain the average nestling age when parental infanticide was observed was 7.3 days (Tortosa & Redondo 1992). For over a hundred years Polish researchers studying the White Stork have discussed whether adult birds kill (throw out from the nest) their offspring or not (e.g. Wodzicki 1877, Sokołowski 1932, Czudek 1935, Ołtuszewski 1937). As early Sokołowski (1932) noticed that a chick found under the nest could have fallen out due to struggle for food between the nestlings. As he puts it, “the folk people, who have fertile imagination, claim that adult storks throw out their chicks themselves, when they 444 Paweł T. Dolata decide that the young will not bring any profit”. Nowadays it is known that parental infanticide does occur in the White Stork and we partly understand what causes this behaviour (Sokołowski 1958, Tortosa & Redondo 1992, Sasvári et al. 1999a, Zieliński 2002). However, no case of parental infanticide has been recorded throughout the author’s 13-year studies on the White Stork in the Ostrów Wielkopolski district, which included systematic and detailed interviews of “nest owners” (people living close to the nest). There have indeed been, though, a few clear cases of a chick falling out of nest accidentally, as a result of struggles between the young. Regarding every nestling found under a nest as thrown out by its parents may cause a large methodological error in a study of brood loss. Even a larger error, resulting in overestimation of parental infanticide is treating parents as killers of their young and cause of brood loss. Papers by Jakubiec (1991) and Guziak & Jakubiec (2006) do not provide information on what basis parents were treated as the agents of brood loss in the nest. At least 1121 broods were regarded as affected by parental infanticide (Guziak & Jakubiec 2006). On the basis of data collected in yearly White Stork nest censuses conducted between 1970–1985, which also included interviews of owners of houses with storks’ nests, Jakubiec (1991) estimated that brood reduction by parents took place in 110 (34.1%) out of 323 cases of chicks’ death and did not report any case of young falling out from their nest. However, almost all of the material was obtained only by means of interviews of villagers – the “nest owners” (registered by researchers who counted nests or by village mayors). Data obtained by Guziak and Jakubiec (2006) was collected using the same method. Field research was carried out and questionnaires were sent out to village mayors (and not directly to nest owners, who provide more reliable information – see Kujawa 1991) and schools, but a primary source of data on brood loss were in almost all cases people living in the nest’s neighbourhood. It is very difficult to observe the exact moment when a chick is thrown out or falls out of nest without continuous nest observation, and it is clear that “nest owners” do not make such observations. Even when an accidental observer is lucky enough to spot this moment, they practically are not able to tell whether the chick was killed by a parent or died in the nest and then was thrown out. Out of 17 papers on White Storks living in various Polish provinces, which were published by Guziak and Jakubiec (2006), only one (Ptaszyk 2006) noticed such probability. Lacking personal observation, the interviewed villagers may have provided a biased, anthropomorphic view of nestlings being thrown out from their nest by their parents, when the latter “know” that it is going to be “a hard year” and that “they won’t be able to feed all their offspring” (Wodzicki 1877, Sokołowski 1931, Ołtuszewski 1937, Lewandowski & Radkiewicz 1991, own data). Information coming from folk people, in most cases not verified by a direct interview is then used as material in scientific papers. Jakubiec (1991) claims that the data in his paper can be regarded as reliable, but it was difficult to determine precisely the true cause of offspring loss. It was shown that data from surveys investigating as simple issues as the number of nests occupied by White Stork pairs or the number of young that fledged the previous year, are not accurate and have limited value (Zieliński & Andrzejczak 1991). They are “Close to Storks” – a project of on-line monitoring of the White Stork nest 445 of even less value in breeding biology, especially in the case of difficult to observe, short events such as parental infanticide. Kujawa (1991) said: “Even in the case of a species that is as well known as the White Stork, the only true information from the surveys is the presence of a White Stork nest in the locality in question”. Moreover, parental infanticide was not recorded during more detailed studies, such as the three-year study conducted in Hungary by Sasvári et al. (1999b), although it was recorded in seven cases out of 37 in continuously monitored White Stork nests in Spain (Tortosa & Redondo 1992). As a matter of fact, in spite of the large number of papers about White Stork breeding success in Poland (see above), probably only one clear and detailed case of parental infanticide, studied as in the Black Stork Ciconia nigra (Kłosowski et al. 2002), was reported by a qualified observer (Borowski 1963). Part of the papers in Jakubiec (1985) reported only the number of eggs and nestling thrown out of nests, without discussing possible causes of these incidents due to lack of sufficient data. However, in the book by Guziak and Jakubiec (2006), which was based on material collected in a similar fashion, more than thousand cases of offspring loss are reported as parental infanticides. It is important to note that in a detailed study performed in Upper Silesia by Profus and Chromik (2001), which was based on field observation and surveys and focused on breeding aspects (including causes of nestlings’ death), the authors did not find any case of parental infanticide in a total of 304 dead nestlings; in 127 of them the cause of death was “unknown (dead nestling was found in or under a nest)”. Using additional cases of nestlings’ death from this area, Profus (2006) still did not find any case of parental infanticide in a total of 392 dead nestlings. No case of parental infanticide was confirmed. A cautious approach should be adopted when we have no clear evidence of parental infanticide. Data from camera monitoring can help to establish how frequently the true parental infanticide occurs in the White Stork in Poland. A very important characteristic of the camera monitoring method is its non-invasiveness as opposed to direct controls of the nest, especially over such key periods as laying or incubating eggs. One of the main problems with research application of cameras in the White Stork nests in Poland is lack of good cooperation between scientists and camera monitoring projects. The main goal of these projects is popularisation of knowledge about the monitored subjects, and sometimes promotion of the project’s organising body; still, achieving this aim may as well include cooperation with and support of researchers. The first on-line White Stork nest camera project in Poland, led by an informal group of “stork lovers”, was launched in 2004 in the Chyby village near Poznań (www.bociany.kalinski.pl). The project’s authors, however, did not take this opportunity to carry out a scientific research. Cooperation with researchers seems to be important or even necessary in all on-line monitoring projects, not only in the case of the White Stork (for instance, in Poland the first projects with the Kestrel Falco tinnunculus nest cameras have just been started). Camera monitoring of a nest appears to be useful in resolving some problems in breeding and feeding biology, as well as in behavioural ecology of the species, including: 446 – – – – – – – – – Paweł T. Dolata accurate time of egg laying and hatching; participation of the male and the female in incubation, including night incubation – Sokołowski (1958) suggested that only the female incubates at night; amount, type and frequency of food delivered to the nest by each of the parents, which is very important due to lack of such data in Poland (Kosicki et al. 2006); changes of parental care during different age of nestlings; food competition between nestlings; social relations between adult and young storks; interaction with alien storks (including nest defence); detailed picture of parental infanticide and discriminating between cases of falling out of nest and being thrown out of nest; precise length of the offspring’s stay in the nest from fledging to leaving the nest. Acknowledgements I want to thank the Przygodzice Community Office and its Chief Mr. Przemysław Kaźmierczak for financial and technical support of the project; to Telekomunikacja Kolejowa Sp. z o.o., Przedsiębiorstwo “Pro-Art”, REXE and Telewizja Interaktywna ITTV firms for technical support; Marcin Rachel, Marek Radziszewski, Tomasz Świątek and Tomasz Wojtasik for their cooperation in the project; and Maciej Bociański, Marcin Rachel, Sv tlana Vránová, Eva Stets-Vithoulka and others for data collection. References Antczak M., Dolata P.T. 2006. Night roosts, flocking behavior and habitat use of the non-breeding fraction and migrating White Storks Ciconia ciconia in the Wielkopolska region (South-Western Poland). In: Tryjanowski P., Sparks T.H., Jerzak L. (eds.) The White Stork in Poland: studies in biology, ecology and conservation. Bogucki Wyd. Nauk., Poznań: 209–224. Borowski S. 1963. 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