JournalTime budget of andThreatened behavioural Taxa traits |of www.threatenedtaxa.org Indian Eagle Owl | 26 November 2015 | 7(14): 8139–8147 Ramanujam The time budget and behavioural traits of young and adult Indian Eagle Owl Bubo bengalensis (Franklin, 1831) (Aves: Strigiformes: Strigidae) in and around a nesting site: ISSN 0974-7907 (Online) Short Communication Short a preliminary report ISSN 0974-7893 (Print) M. Eric Ramanujam OPEN ACCESS Principal Investigator (Faunistics), Pitchandikulam Bioresource Centre / Pitchandikulam Forest Consultants, Auroville, Tamil Nadu 605101, India [email protected] Abstract: A family of the Indian Eagle Owl Bubo bengalensis was Activity profiles, as deduced from time budgeting and monitored at their nest site at Nanmangalam Reserve Forest on the behavioural patterns, provide an ethological profile of a outskirts of Chennai City from 5 January to 8 March 2011. Various behavioural patterns were identified and the time spent on each species since these are a quantitative description of how activity was noted. All three types of subjects (viz.: breeding male, animals partition their time in relation to their activities brooding/incubating female and young) showed different behavioural characteristics. In the breeding female, high intensity activities were (Kurup & Kumar 1993; Ramachandran 1998). Patterns incubation, brooding, vigilance and out of sight (construed to be out of activity can vary widely between species and these hunting) and low intensity activities comprised comfort movements, activity budgets are fundamental to the study of life feeding, pellet regurgitation, feeding young, prey delivery and disturbed at the nest. In the young, high intensity activities were histories and ecology of a species (Evers 1994; Hamilton resting and moving, while low intensity activities were feeding, pellet et al. 2002; Jonsson & Afton 2006). Time activity regurgitation and wing flapping. In the male, the bulk of time was budgets reflect not only on behavioural aspects but spent in vigilance and the other high intensity activity was out of sight (construed to be hunting). Low intensity activities included comfort also on individual physical condition, food availability, movements and prey delivery. The male hunted more than the female. social structure and environmental conditions (Pauls Forty-five prey items were delivered by the two parents and these 1998). Hence, they are the fundamental parameters items were identified to the species or generic level. for understanding the behavioural ecology of a species, Keywords: Behavioural traits, biomass, comfort movements, which can holistically influence conservation biology. descriptive approach, ethograms, long-term activities, short-term A case in point was the study on the time budget activities. Bubo bengalensis Indian Eagle Owl NOT DATA NEAR CRITICALLY EXTINCT LEAST VULNERABLE ENDANGERED EXTINCT EVALUATED DEFICIENT CONCERN THREATENED ENDANGERED IN THE WILD NE DD LC NT VU EN CR EW EX DOI: http://dx.doi.org/10.11609/jott.2429.7.14.8139-8147 Editor: Reuven Yosef, Ben Gurion University of the Negev, Eilat Campus, Israel. Date of publication: 26 November 2015 (online & print) Manuscript details: Ms # o4266 | Received 24 January 2015 | Final received 14 October 2015 | Finally accepted 26 October 2015 Citation: Ramanujam, M.E. (2015). The time budget and behavioural traits of young and adult Indian Eagle OwlBubo bengalensis (Franklin, 1831) (Aves: Strigiformes: Strigidae) in and around a nesting site: a preliminary report. Journal of Threatened Taxa 7(14): 8139–8147; http://dx.doi.org/10.11609/jott.2429.7.14.8139-8147 Copyright: © Ramanujam 2015. Creative Commons Attribution 4.0 International License. JoTT allows unrestricted use of this article in any medium, reproduction and distribution by providing adequate credit to the authors and the source of publication. Funding: None. Conflict of Interest:The author declares no competing interests. Acknowledgements: I wish to thank the Principal Chief Conservator of Forests and Chief Wildlife Warden, and District Forest Officer, Chengalpattu Division for granting us the ‘permit for entering into Nanmangalam Reserve Forest and carrying out research’ (Order dated 06.12.2010, Ref. No. WL5/53750/2010). I also wish to thank our photographer A. Lakshmikantan for diligently following the owls and photographing them. M. Bubesh Guptha was an enormous help in rendering the statistics and keeping up with my mercurial way of thinking in presenting this article and so was our systems manager P. Karunakaran. 8139 Time budget and behavioural traits of Indian Eagle Owl Ramanujam and behavior of the nesting Bald Eagle Haliaeetus Aumann 2001; Madders & Whitfeld 2006). leucocephalus, which has had an impact on the In this study, I present the time budget and activity protection of nesting sites and curtailment of human pattern of a pair of Indian Eagle Owls and their young activity of pertinent areas during the breeding season both during the day and night. (Cain 2010). Published information on the activity budget of Material and Methods Indian birds is very poor—only a few case studies exist Study area: Nanmangalam Reserve Forest (NRF) concerning the Pheasant-tailed Jacana Hydrophasianus (12093’N & 80017’E) is spread over 320.92ha and is chirurgus, Bronze-winged Jacana Metopidius indicus cradled by the vast townships of Tambaram, Pallikaranai, (Ramachandran 1998), Southern Crow Pheasant Alandur and Velachery on the outskirts of Chennai, Centropus sinensis (Natarajan 1991), White-breasted Tamil Nadu in southern India (Fig. 1). The vegetation Kingfisher Halcyon smyrnensis (Asokan & Ali 2010), of NRF is described as ‘Vandalur scrub’. Hillocks occupy Indian Roller Coracias benghalensis (Sivakumaran & approximately half of the area, predominantly towards Thiyagesan 2003) and Indian Myna Acridotheres tristis the centre. Low lying plains are present along the (Mahabal 1991). Among owls, globally, the only species boundary on both the eastern and western sides and whose activity budgets have been studied are the three ponds occur there. In the years 1963-1980, areas Burrowing Owl Athene cunicularia (Haug et al. 1990; were leased out for quarrying rocks. Subsequently, Plumpton & Lutz 1993; Chipman 2006; LaFever et al. when the Forest Conservation Act came into force, the 2008) and the Snowy Owl Bubo scandiacus (Sheilds 1969; practice was discontinued. The signs of the quarrying Krivtsov 1988; Potapov & Sale 2012). Activity patterns industry are still visible in the form of five deep and for some nocturnal owls are available (e.g., Bosakowski steep sided water filled depressions – the nesting areas 1989; Sovern et. al. 1994; Delany & Grubb 1999) but of Bubo bengalensis (Anonymous 2009). time budgets were not prioritized. This is contrary to Methods: Studies on B. bengalensis in NRF lasted diurnal raptors whose time budgets and activity patterns from December 2010 to November 2011 - a period have been studied in detail (e.g., Fischer 1986; Collopy & of one year. On 05 January 2011 a nest scrape with Edwards 1989; Jimenez & Jasic 1989; Watson et al. 1991; three eggs (Image 1) was located (date of laying Figure 1. Study area 8140 Journal of Threatened Taxa | www.threatenedtaxa.org | 26 November 2015 | 7(14): 8139–8147 Time budget and behavioural traits of Indian Eagle Owl Ramanujam © A. Lakshmikantan birds was deduced. Since we did not know the exact date of hatching and did not have permission to handle any wildlife, the approximate age of the nestlings was inferred using feather morphology/molt patterns (Ramanujam & Murugavel 2009). We chose a basic descriptive approach because of the small sample size (one nest and five subjects) and not a hypothesis testing approach where investigators have estimated outputs based on many observations and large sample sizes. LaFever et al. (2008) adopted the descriptive approach concerning A. cunicularia in spite of a hypothesis testing option “…. because for a non-experimental study of behavior, we expect a priori that there were differences among groups of individuals observed. This follows the recent argument for emphasizing estimation rather than statistical significance of null hypotheses that are trivial and Image 1. Nest scrape with overhang discovered on 05 January 2011. presumably false (Yoccov 1991; Johnson 1999)”. I wish to state that it was impossible to arrive at the exact moment when behaviour of long-term activities unknown). This belonged to a single pair of owls that was concerned - for example, ‘vigilance’ and ‘out of were quite comfortable with humans after having been sight’. We had recorded these in hours/minutes and had photographed over many years by members of Pelican to balance them out when filling in the spreadsheet and Nature Club. This nest and its environs were watched converting data to seconds. This is the reason why most, for the next nine and half weeks (up to the middle of the if not all authors dealing with activity budgets and time second week of March 2011) on a 24- hour basis twice a profiles prefer to provide percentage values rather than week. Our vigil usually began around 16.00hr and lasted raw data (see Supplementary file). Here I have provided until the same time the next day. Occasionally, due to raw data along with percentages converted from hours inability to get to the site on time, we began later but and minutes to seconds. Some rounding off had to always maintained the 24 hour observation period. By be resorted to so as to suit the 86,400