Comparative Nest Site Selection and Breeding Success in 2 Sympatric Ardeids, Black-Crowned Night-Heron (Nycticorax nycticorax) and Little Egret (Egretta garzetta) in the Axios Delta, Macedonia, Greece

Abstract

We studied nest site selection and breeding success of Black-crowned Night-Herons (Nycticorax nycticorax) and Little Egrets (Egretta garzetta) in the Axios Delta (Greece) from 1988 to 1990. Both species nested above the middle of tamarisks and alders. Nest density varied each year from 333.3 nests/ha to 646.2 nests/ha for Blackcrowned Night-Herons and 291.7 nests/ha to 421.5 nests/ha for Little Egrets. Black-crowned Night-Herons started to breed earlier than Little Egrets, also placing their nests higher (mean nest height: 4.21 ? SD of 0.80 m and 3.54 ? SD of 0.71 m for Black-crowned Night-Herons and Little Egrets, respectively). The nearest neighbors were conspecifics for Black-crowned Night-Herons and heterospecifics (Black-crowned Night-Herons) for Little Egrets. The mean distance of the nearest neighbor was similar in both species (1.02 ? SD of 0.46 m and 1.11 ? SD of 0.37 m for Black-crowned Night-Herons and Little Egrets, respectively). In contrast to late-nesting Little Egrets that located their nests lower, Black-crowned Night-Herons maintained a constant nest distance from the ground. The mean clutch size (3.40 ? SD of 0.60 and 4.32 ? SD of 0.81 for Black-crowned Night-Herons and Little Egrets, respectively) and the mean chick survival per nest (2.48 ? SD of 0.95 and 2.53 ? SD of 1.28 for Black-crowned Night-Herons and Little Egrets, respectively) of both species varied among the study years. No variation was observed in the means of clutch size and chick survival per nest of Black-crowned Night-Herons among the 3 sub-periods of the breeding season. Little Egret clutch size and mean number of eggs hatched was smaller in late nesters, but no difference was observed in chick survival per nest between early and late nesters. Nest placement did not affect chick survival in Black-crowned Night-Herons and only marginally in Little Egrets.

Vertical nest stratification and breeding success in a six mixed-species heronry in Taeseong, Chungbuk, Korea

“…In some areas where the black-crowned night herons and little egrets competed for nest sites, the early-breeding blackcrowned night herons nested higher than the little egrets. The little egrets showed reduced hatching success, while the black-crowned night herons showed no variation in this rate (Kazantzidis et al 1997). …”

Breeding success of Black-crowned Night Heron (Nycticorax nycticorax), Little Egret (Egretta garzetta) and Cattle Egret (Bubulcus ibis) (Aves: Ardeidae) in relation to nest height in the South Caspian Sea

“…Cattle Egrets, Black-crowned Night Herons and Little Egrets, like other herons, are quite adept at exploiting available local nesting resources such as vegetation type and height (Voisin 1991;Perennou et al 1996;Kazantzidis et al 1997). The majority of nests were located in Alnus glutinosa trees.…”

“…Some studies have been made of nest-site selection by the Cattle Egret (Bubulcus ibis) and Little Egret (Egretta garzetta) (Arendt & Arendt 1988;Kazantzidis et al 1996) and its effect on breeding success (Kazantzidis et al 1997). Studies of nest-site selection by the Cattle Egret and Little Egret have also been conducted in subtropical North America and in southern Europe (Telfair 1983;Arendt & Arendt 1988;Kazantzidis et al 1997), but information on the nesting success of these species in south and southeast Asia is scarce.…”

“…Studies of nest-site selection by the Cattle Egret and Little Egret have also been conducted in subtropical North America and in southern Europe (Telfair 1983;Arendt & Arendt 1988;Kazantzidis et al 1997), but information on the nesting success of these species in south and southeast Asia is scarce.…”

“…Nest-site parameters also influence hatching success (Ludwig et al 1994;Kazantzidis et al 1997;Hilaluddin et al 2003) and fledging success (Buckley & Buckley 1980). While nest-site characteristics appear less important in colonies with small numbers of breeding pairs (Harris et al 1997), in big colonies containing one or more species, factors such as vegetation type, horizontal-vertical layering and site selection can affect breeding performance (Uzun 2009).…”