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  • Tawny owl VHF telemetry studies in Northern Spain

    Dr Iigo Zuberogoitia X. Slyomcsalogat (10. 'Falcon luring')

    28th February 1st March 2015 Szarvas, Hungary

    Dr Iigo Zuberogoitia & Gorka Burgos

  • Knowledge about distribution and status: Six years censusing tawny owls in Bizkaia, Northern Spain.

    Zuberogoitia, I., Campos, L.F. 1998. Censusing owls in large areas: a comparison between methods. Ardeola, 45 (1): 47-53. Zuberogoitia, I., Campos, L.F. 1997. Intensive census of nocturnal raptors in Biscay. Munibe. 1997, 49: 117-127. Zuberogoitia, I., Martnez, J.A. & Alonso, R. 2011. Censusing owls. Some considerations to achieve better results. In

    Zuberogoitia, I. & Martnez, J.E. (Eds). Ecology and Conservation of European Forest-Dwelling Raptors, pp 137-145. Diputacin Foral de Bizkaia. Bilbao.

    Zuberogoitia, I. &. Martnez, J.A 2003. Crabo Comn. En R. Marti y J.C. del Moral. (Eds). Atlas de las aves reproductoras de Espaa. Pp 320-321. Direccin General de la Conservacin de la Naturaleza-Sociedad Espaola de Ornitologa. Madrid.

    Zuberogoitia, I. 2012. Crabo comn. En SEO/BirdLife. Atlas de las aves en invierno en Espaa 2007-2010, pp 336-337. Ministerio de Agricultura, Alimentacin y Medio Ambiente-SEO/BirdLife. Madrid.

    Knowledge about vocal behaviour of tawny owls Zuberogoitia, I. & Martnez, J.A. 2000. Methods for surveying Tawny Owl Strix aluco populations in large areas. Biota, Vol 1,

    N 2: 137-146.

    Knowledge about breeding of tawny owls Zuberogoitia, I., Martnez, J.A., Iraeta, A., Azkona, A. & Castillo, I. 2004. Posible first record of double brooding on Tawny

    Owl Strix aluco. Ardeola, 51 (2): 435-437. Zuberogoitia, I. 2011. Weather influence on breeding success of the tawny owl on the southwest limit of Eurosiberian

    Region. In Zuberogoitia, I. & Martnez, J.E. (Eds). Ecology and Conservation of European Forest-Dwelling Raptors, pp 184-189.

    Knowledge about inter-guild relationships: Zuberogoitia, I., Martnez, J.A., Zabala, J. & Martnez, J.E. 2005. Interspecific aggression and nest-site competition in a

    European owl community. Journal of Raptor Research, 39(2): 156-159. Zuberogoitia, I., Martnez, J.E., Zabala, J., Martnez, J.A., Azkona, A., Castillo, I. & Hidalgo, S. 2008. Social interactions

    between two owl species sometimes associated with intraguild predation. Ardea 96 (1): 109-113.


  • Background

    Other works related to the vocal behavior of owls: Martnez, J.A., Zuberogoitia, I., Cols, J. & Maca, J. 2002. Use of recorder calls for detecting Long-eared Owls Asio otus.

    Ardeola, 49 (1): 97-101 Martnez, J.A. & Zuberogoitia, I. 2002. Factors affecting the vocal behaviour of Eagle Owl Bubo bubo: effects of sex and

    territorial status. Ardeola, 49 (1): 1-10. Martnez, J.A. & Zuberogoitia, I. 2003. Factors afecting the vocal behavior of Eagle Owls Bubo bubo: effects of season,

    density and territory quality. Ardeola, 50 (2): 255-258. Zuberogoitia, I., Zabala, J., Martnez, J.A., Hidalgo, S., Martnez, J.E., Azkona, A. & Castillo, I. 2007. Seasonal dynamics in

    social behaviour and spacing patterns of the Little Owl Athene noctua. Ornis Fennica 84, 173-180. Zuberogoitia, I., Zabala, J. & Martnez, J.E. 2011. Bias in little owl population estimates using playback techniques during

    surveys. Animal Biodiversity and Conservation, 34.2: 395-400.

    Other works related to the habitat selection of owls: Martnez, J.A., Serrano, D. & Zuberogoitia, I. 2003. Predictive models of habitat preferences for the Eurasian Eagle Owl Bubo

    bubo: a multi-scale approach. Ecography. 26: 21-28. Martnez, J.A. & Zuberogoitia, I. 2004. Effects of habitat loss on perceived actual abundance of the Little Owl athene noctua.

    Ardeola, 51 (1): 215-219. Martnez, J.A. & Zuberogoitia, I. 2004. Habitat preferences and causes of population decline for Barn Owl (Tyto alba); a multi-

    scale approach. Ardeola, 51 (2): 342-344. Martnez, J.A. & Zuberogoitia, I. 2004. Habitat preferentes for Long-eared Owl Asio otus and Little Owl Athene noctua in semi-

    arid environments at three spatial scales. Bird Study, 51: 163-169. Zabala, J., Zuberogoitia, I., Martnez, J.A., Martnez, J.E., Azkona, A., Hidalgo, S. & Iraeta, A. 2006. Occupance and

    abundance of Little Owl (Athene noctua) in an intensively managed forest area in Biscay. Ornis Fennica 83: 97-107. Martnez, J.A., Zuberogoitia, I., Martnez, J.A., Zabala, J. & Calvo, J.E. 2007. Patterns of territory settlements by Eurasian

    scops-owl (Otus scops) in altered semi-arid lanscape. J. Arid Environm. 69: 400-409.

  • Background Goals

    The main goals we planned were: To study two different populations in two different types of forest structure: large deciduous forests with field-grass for cattle, mainly cows, and few buildings (Burcea) vs pine timber plantations with dense but disperse buildings with gardens and field-grass for sheep (Durango).

  • Background Goals

    Burcea Burcea

    Durango Durango

  • Background Goals

    The main goals we planned were: Of course, we wanted to describe the habitat selection, considering both foraging and resting habitats. The main questions were: 1. Could we hope differences in density and home range? 2. Could we hope differences in habitat use? 3. Could we hope differences in breeding success? 4. Could we hope differences in vocal behavior?

  • Background Goals

    The main goals we planned were: But also we wanted to know: 1. Is the vocal behaviour related to population density, habitat quality and individual

    quality? 2. Do tawny owls use vocal behaviour in the borders of the home range? Or

    perhaps it is also conditioned by the habitat and population structure? 3. And, once in this step, could we hope differences in the results of census using


  • Background Goals

    The main goals we planned were: And, trying to go further: 1. Do the habitat quality condition the moult of tawny owls? 2. Do the human density and the use of natural resources condition the behaviour

    of tawny owls?

  • Background Goals Methods

    Study area selection: 1- Radio-tracking tawny owls with no financial support (we received a little grant for materials Gobierno Vasco and Gorka Burgos received a grant during three months from the Santander Bank) We bought 20 transmitters (Biotrack) for one year of life-span. We needed to trap 10 tawny owls in each study area. But, what is more important, we needed to trap neighbours. All birds in the same two areas. We selected these two areas because I live in one and Gorka Burgos (he is doing his PhD Thesis with this project) lives in the second. It is important to make it easy! We were to spend hundreds of hours during daytime and nights in the following years, so we needed to have easy and quick access to the areas.

  • Background Goals Methods

    Trapping owls: 2- We started trapping four owls in March 2013 in one area and we waited till the autumn for continuing. We trapped tawny owls using a broadcast (voices of male, female or both) and a mist-net (21 x 3 m, 7 cm mesh). The best season to trap tawny owls was the period from November to January. For trapping tawny owls: 1- we playbacked the records and waited 10 minutes for answer. 2- If we obtained weak answer or silent, we did not set the net and moved to another point. 3- If tawny owls came hooting and flying above the tape, we set the net cutting the trajectory between the canopy. 4- We stopped the tape and then we set the net until 9 m height, and latter we switched on the tape again. 5- Normally the owl is trapped in few minutes if the net is correctly set.

  • Background Goals Methods

    Tagging owls: 3- We ringed, measured, dated and took the moult card of the trapped owls, and finally we put the tags in the back of the owls. We sexed tawny owls listening them, before trapping!

  • Background Goals Methods

    Monitoring radio-tracked owls: 4- We used homing technique in order to detect the positions of owls with precision. 5- To avoid pseudoreplication we only obtained one position per night, 2-4 nights per week and one-two diurnal positions per week. 6- We pointed out the position, data and time, the type of forest, the activity and the weather. But also we pointed out every time that the target owl produced a voice and the type of voice. We also pointed out the vocal activity of every tawny owl (target or no) detected during the radio-tracking period.

  • Background Goals Methods

    Processing data: 7- We noted every position each following day in a GIS software (Quantum Gis) .

  • Background Goals Methods

    Testing vocal activity census validation: 8- We tested the response of target owls to the broadcast during winter. We tested the response 3-4 times/individual from November till February. We used different voices each time (tawny owls are able to recognize the voice of their neighbours and can learn about the voice you use to call them). Basically, we are trying to develop the same protocol that we used in:

  • Background Goals Methods

    Monitoring breeding success: 9- We detected and described nesting sites and we monitored the breeding success of each monitored owl. 10- We set camera traps and infrared barriers with a camera in the nest sites in order to monitor the type of prey items that each owl carried to the nestlings.

  • Background Goals Methods

    Analysing prey abundance: 11- We used sherman traps in order to analyse the abundance of micro-mammals in di