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Nocturnal predation by total of eight Storm-petrel rings (Figure 1). At least two pellets also contained the remains the Grey Heron Ardea of small shrimp, probably Palaemon serratus, cinerea on the European and two other pellets contained a small pharyngeal bone of an unidentified wrasse Storm-petrel Hydrobates species, and an unidentified periwinkle pelagicus species (Littorina sp.) respectively. Grey Heron Ardea cinerea were then found in the Bernard Cadiou1,2 same location as some pellets, indicating that the Grey Heron was the predator. In 2012, a Email: [email protected] Grey Heron was regularly recorded roosting 1 Bretagne Vivante - SEPNB, 186 rue during the day in two areas, away from Anatole France, BP 63121, F-29231 Brest Storm-petrel nest-sites, and ten pellets were cedex 3, France; found, containing three rings. Careful 2 Réserve naturelle nationale d’Iroise, Maison examination also revealed a few Storm-petrel de l’environnement insulaire, Le Bourg, F- bones, but totally soft and elastic as a result 29259 île Molène, France. of the strong action of gastric juices.

The European Storm-petrel Hydrobates From 2009 to 2012, this (presumed the pelagicus colonies located in the Iroise same) Grey Heron had killed at least 17 National Nature Reserve, Molène archipelago, ringed , previously mist-netted at night western Brittany, are the largest in France (12) or ringed as breeders (3) or as chicks with a total of 710–765 apparently occupied (2) at nest-sites. Amongst them, there was sites (AOS) in 2012 (Cadiou et al. 2004; one of the oldest Storm-petrels known Bretagne Vivante 2012). European Storm- from Iroise, a mist-netted in July 1983 petrels nest mainly in cavities under rocks, in and killed in August 2011, 28 years since former European Rabbit Oryctolagus ringing and thus at least 30 years old, since cuniculus burrows or in boulder beaches. Storm-petrels normally begin to frequent colonies from the age of two, and very These colonies are visited regularly from late rarely at the age of one year (pers. obs.). March to late October to search for pellets This Storm-petrel had been controlled at regurgitated by in to evaluate the night almost every year during the last intensity of predation of European Storm- decade before its death, and its age was petrels (hereafter ‘Storm-petrels’). About close to the British and Irish record for the 100–400 pellets have been found annually species of 32 years between ringing and since the mid 1990s (Bretagne Vivante recapture (Robinson & Clark 2012). 2012). All pellets were examined to search for possible rings of Storm-petrels, as adults The Grey Heron has been established as and chicks have been ringed annually since breeder in the Molène archipelago since the mid 1970s and 1997 respectively. 2002, with nests built on the ground, generally on the foreshore (Cadiou & Le Gall In September 2009, an unusually large pellet 2006). In 2009–2012, 7–11 pairs bred but was found that contained many feathers and none were on islands with breeding Storm- three rings from Storm-petrels. The predator petrels (Bretagne Vivante 2012). It has could not be identified. In June 2010, two probably been the same individual Grey similar pellets, containing one and two Heron which has specialised in this type of Storm-petrel rings, respectively, were found nocturnal predation in recent years (see Hall but the predator still could not be identified. & Kress (2008) about specialisation), but In 2011, a further 15 such pellets were whether it is a local breeder or a non- reported from June to August, containing a breeder is unclear. This individual probably

SEABIRD 26 (2013) 93 Note

Figure 1. A regurgitated Grey Heron Ardea cinerea pellet containing European Storm-petrel Hydrobates pelagicus remains, with a ring on the surface (on the left), found in June 2011 in the Molène archipelago. © Bernard Cadiou.

rests on the island, on the lookout for from burrows during the day (Harris 1969). Storm-petrels landing at or leaving their However, such predation on storm-petrels burrows at dusk, at night or at dawn, may go unnoticed, because it occurs at night presumably adopting the ‘stand and wait’ and the pellets are regurgitated by herons at feeding behaviour (Willard 1977). As with places used for roosting, probably sometimes gulls, predation by the heron almost located outside the storm-petrel colonies. certainly occurred by night in the Molène archipelago, Storm-petrels being Grey Heron can thus be added to the list of inaccessible in their nest-sites by day, and predators of Storm-petrels in Brittany: Great there were no signs of attempts of Black-backed Larus marinus, Herring L. extraction in the soil at the entrances of the argentatus and Lesser Black-backed Gulls L. burrows. The nocturnal activity of these fuscus (Cadiou et al. 2004; Bretagne Vivante predators may probably be sometimes 2012), Short-eared Asio flammeus facilitated by ambient light from the moon. (Cadiou 2003), Neovison vison (Cadiou 2008), and Brown Rattus norvegicus Nocturnal or crepuscular foraging is common or Black Rats R. rattus (Cadiou 2002) acting in ardeid species such as herons of the genus on the colonies themselves; and Cats Felis Ardea (Cramp & Simmons 1977; Van Vessem catus on neighbouring islands inhabited by & Draulans 1986; McNeil et al. 1993, 1999; humans, such as Molène and Ouessant Black & Collopy 2002). Herons feed (Kerbiriou & Le Viol 1999; Bretagne Vivante opportunistically on various types of prey 2012); and Peregrine Falco peregrinus (fishes, amphibians, invertebrates, mammals, at sea, with three cases recorded at different birds: Cramp & Simmons 1977; Fasola 1994). localities in Brittany in recent years (E. Cozic, Amongst , terns are the group Y. Février & B. Dumeau pers. comm.). reported most regularly as prey of heron species (e.g. Hunter & Morris 1976; Ramos & Acknowledgments del Nevo 1995; Barbour et al. 2000; Williams The study was conducted on the Iroise & Ward 2006; Perrow et al. 2010). Williams & National Nature Reserve, managed by the Ward (2006) found only one reported case of NGO Bretagne Vivante-SEPNB with predation of storm-petrels by herons, this financial support of the Conseil Général du being in the Galapagos Islands where Great Finistère, landowner of the reserve, the Blue Heron Ardea herodias extracted young Direction Régionale de l’Environnement, de Madeiran Storm-petrels castro l’Aménagement et du Logement (DREAL

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Bretagne, French Ministry of Environment) seabird colony: implications for management. and the Conseil Régional de Bretagne. Rings The Wilson Journal of 120: 637–640. were provided by the Centre de Recherches Harris, M. P. 1969. The biology of Storm Petrels in par le Baguage des Populations d’Oiseaux the Galapagos Islands. Proceedings of the (CRBPO). I am very grateful to Hélène California Academy of Science 37: 95–166. Mahéo and David Bourles, wardens of the Hunter, R. A. & Morris, R. D. 1976. Nocturnal reserve, to all the volunteers involved predation by a Black-crowned Night-Heron at a annually in fieldwork as well as to Mike Common Tern colony. Auk 93: 629–633. Harris and Martin Heubeck for helpful Kerbiriou, C. & Le Viol, I. 1999. Prédation de comments and improvements. l’Océanite tempête Hydrobates pelagicus par le Chat domestique Felis domesticus dans References l’archipel de Molène et sur l’île d’Ouessant Barbour, D. L, Morris, R. D. & Moore, D. J. 2000. (Finistère). Alauda 67: 119–122. and chick fates of Common Terns in areas of McNeil, R., Benoît, R. & DesGranges, J. L. 1993. high and low nest density. Journal of Field Daytime and nighttime activity at a breeding Ornithology 71: 34–43. colony of Great Blue Herons in a nontidal Black, B. B. & Collopy, M. W. 1982. Nocturnal environment. Canadian Journal of Zoology 71: activity of Great Blue Herons in a north Florida 1075–1078. salt marsh. Journal of Field Ornithology 53: McNeil, R., Rojas, L. M., Cabana, T. & Lachapelle 403–406. P. 1999. Vision and nocturnal activities in Bretagne Vivante 2012. Rapport d’activité 2012 wading birds and shorebirds. In: Adams, N. J. & de la Réserve Naturelle d’Iroise. Unpublished Slotow, R. H. (eds.) Proceedings of the 22th report Bretagne Vivante - SEPNB, Brest. International Ornithological Congress, Durban: Cadiou, B. 2002. Oiseaux marins nicheurs de 2691–2710. BirdLife South Africa, Johannesburg. Bretagne. Les cahiers naturalistes de Bretagne Perrow, M. R., Gilroy, J. J., Skeate, E. R. & N°4. Conseil Régional de Bretagne, Editions Mackenzie, A. 2010. Quantifying the relative Biotope, Mèze use of coastal waters by breeding terns: towards Cadiou, B. 2003. Prédation du Hibou des marais effective tools for planning and assessing the Asio flammeus sur l’Océanite tempête ornithological impacts of offshore wind farms. Hydrobates pelagicus. Alauda 71: 295–297. ECON Ecological Consultancy Ltd. Final report Cadiou, B. (coord.) 2008. ‘Oiseaux marins to COWRIE Ltd. nicheurs de Bretagne, 2007’. Contrat de projets Ramos, J. A. & del Nevo, A. J. 1995. Nest-site État-Région (CPER 2007–2013), programme selection by Roseate Terns and Common Terns in Sauvegarder et Valoriser le Patrimoine Naturel. the Azores. Auk 112: 580–589. Unpublished report Bretagne Vivante - SEPNB / Robinson, R. A. & Clark, J. A. 2012. The Online Conseil Régional de Bretagne. Ringing Report: in Britain & Ireland Cadiou, B., Pons, J.-M. & Yésou, P. (eds.) 2004. in 2011. BTO, Thetford (http://www.bto.org/ Oiseaux marins nicheurs de France métropol- ringing-report, created on 7 September 2012). itaine (1960–2000). Éditions Biotope, Mèze. Van Vessem J. & Draulans D. 1986. Factors Cadiou, B. & Le Gall, J.-Y. 2006. Implantation et affecting the length of the breeding cycle and nidification au sol du Héron cendré Ardea cinerea the frequency of nest attendance by Grey dans l’archipel de Molène. Ornithos 13: 268–270. Herons Ardea cinerea. Bird Study 33: 98–104. Cramp, S. & Simmons, K. E. L. (eds.) 1977. The Willard, D. E. 1977. The feeding ecology and Birds of the Western Palearctic. Vol. 1. Oxford behavior of five species of herons in University Press, Oxford. southeastern New Jersey. Condor 79: 462–470. Fasola, M. 1994. Opportunistic use of foraging Williams, A. J. & Ward, V. L. 2006. Sacred Ibis and resources by heron communities in southern Grey Heron predation of Cape Cormorant Europe. Ecography 17: 113–123. and chicks; and a review of Ciconiiform birds as Hall, C. S. & Kress, S. W. 2008. Diet of nestling seabird predators. Waterbirds 29: 321–327. Black-crowned Night-Herons nesting in a Maine

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