<abstract xmlns="http://www.w3.org/1999/xhtml"><p> Several bird species utilize artificial structures for communal roosting. Between 26 May and 28 Jun 2012, the selection of buoys and times of departure by Mediterranean Shags Phalacrocorax aristotelis desmarestii were studied at three communal roosts within shellfish farms in the Bays of Sv. Jernej (Debeli rtič), Strunjan and Piran (Sečovlje). A total of 3,110 buoys were counted and categorized into two groups according to their shape (horizontal and vertical) and colours. The black horizontally floating buoys were of two types (barrelshaped and oval). The Shags chose to utilize the horizontally floating buoys only, most often black and white in colour. Owing to their poorer stability and smaller standing surface, the vertically floating buoys are clearly unsuitable for them. The highest share of Shags with regard to the number of buoys of separate types was registered on black barrel-shaped buoys. As the percentage of occupied buoys was similar at all roost sites (36-39%), it was deduced that Shags distribute evenly among roosts, regardless of the number of individuals present in the Slovenian sea. At the larger roost at Debeli rtič, the percentage of adult individuals (73.5%) was greater than at Strunjan (42.5%). This could be due to the competition for better places, given that competitively stronger individuals select safer larger roosts. Between 5.42 and 9.00 hrs, 53.3% and 69.1% of Shags departed from the roost sites at Debeli rtič and Strunjan, respectively, with the majority of departures recorded between 7.50 and 8.30 hrs. They left their roosts mostly individually (48.7%) or in pairs (23.3%), at Debeli rtič predominantly in the SW (58.9%) and W (16.9%) directions, and at Strunjan in the NE (42.3%) and N (38.5%) directions.</p></abstract>

Several bird species utilize artificial structures for communal roosting. Between 26 May and 28 Jun 2012, the selection of buoys and times of departure by Mediterranean Shags Phalacrocorax aristotelis desmarestii were studied at three communal roosts within shellfish farms in the Bays of Sv. Jernej (Debeli rtič), Strunjan and Piran (Sečovlje). A total of 3,110 buoys were counted and categorized into two groups according to their shape (horizontal and vertical) and colours. The black horizontally floating buoys were of two types (barrelshaped and oval). The Shags chose to utilize the horizontally floating buoys only, most often black and white in colour. Owing to their poorer stability and smaller standing surface, the vertically floating buoys are clearly unsuitable for them. The highest share of Shags with regard to the number of buoys of separate types was registered on black barrel-shaped buoys. As the percentage of occupied buoys was similar at all roost sites (36-39%), it was deduced that Shags distribute evenly among roosts, regardless of the number of individuals present in the Slovenian sea. At the larger roost at Debeli rtič, the percentage of adult individuals (73.5%) was greater than at Strunjan (42.5%). This could be due to the competition for better places, given that competitively stronger individuals select safer larger roosts. Between 5.42 and 9.00 hrs, 53.3% and 69.1% of Shags departed from the roost sites at Debeli rtič and Strunjan, respectively, with the majority of departures recorded between 7.50 and 8.30 hrs. They left their roosts mostly individually (48.7%) or in pairs (23.3%), at Debeli rtič predominantly in the SW (58.9%) and W (16.9%) directions, and at Strunjan in the NE (42.3%) and N (38.5%) directions.

Roost-Site Characteristics of the Mediterranean Shag Phalacrocorax Aristotelis Desmarestii Along the Slovenian Coast

Nacionalni inštitut za biologijo, Večna pot 111, SI–1000 Ljubljana, Slovenija

Na griču 3, SI–3202 Ljubečna, Slovenija

Jurjevica 61, SI–1310 Ribnica, Slovenija

Velika Pirešica 27k, SI–3310 Žalec, Slovenija

Mala Slevica 2, SI–1315 Velike Lašče, Slovenija

Acrocephalus

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Several bird species utilize artificial structures for communal roosting. Between 26 May and 28 Jun 2012, the selection of buoys and times of departure by...

Roost-Site Characteristics of the Mediterranean Shag Phalacrocorax Aristotelis Desmarestii Along the Slovenian Coast

Published Online: May 27, 2014

Page range: 5 - 11

Received: Jul 19, 2012

Accepted: Feb 24, 2014

DOI: https://doi.org/10.2478/acro-2013-0001

Keywords
Mediterranean Shag, Phalacrocorax aristotelis desmarestii, roostsite, buoys, Slovenian coast

© by Dejan Bordjan

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Roost-Site Characteristics of the Mediterranean Shag Phalacrocorax Aristotelis Desmarestii Along the Slovenian Coast

Published Online: May 27, 2014

Page range: 5 - 11

Received: Jul 19, 2012

Accepted: Feb 24, 2014

DOI: https://doi.org/10.2478/acro-2013-0001

KeywordsMediterranean Shag, Phalacrocorax aristotelis desmarestii, roostsite, buoys, Slovenian coast

© by Dejan Bordjan

This article is distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Keywords
Mediterranean Shag, Phalacrocorax aristotelis desmarestii, roostsite, buoys, Slovenian coast