Fr: Héron des Galapagos
All: Lavareiher
Esp: Garcilla de lava
Ita: Airone delle Galapagos
Nd: Galápagosreiger
Sd: Galapagoshäger
Photographers:
Roger Ahlman
Pbase Galleries Peru and Ecuador
John Anderson
John Anderson Photo Galleries
Text by Nicole Bouglouan
Sources:
Animal Diversity Web (University of Michigan Museum of Zoology)
Wikipedia, the free encyclopaedia
Galapagos or Lava Heron
Butorides sundevalli
Pelecaniformes Order – Ardeidae Family
INTRODUCTION:
The Galapagos Heron also known as Lava Heron is endemic to the Galapagos Islands. Its slate-grey plumage allows it to blend in with the lava rocks.
This heron is still considered sometimes a subspecies or a colour morph of the Green-backed Heron (B. striatus). But full species or subspecies, the Galapagos Heron is a good example of the adaptation of the fauna to these islands.
DESCRIPTION OF THE BIRD:
Biometrics:
Length: 35 cm
Wingspan: 63 cm
Weight: 190-235 g
The Galapagos Heron is a small heron with dark slate-grey to blackish plumage overall, with silvery sheen on back and greenish gloss on wings.
On the head, we can see a short crest on the hind crown.
During the breeding season, the long beak is glossy black. The eyes are pale yellow to pale orange. The lores turn green to bright blue. Legs and feet are bright orange.
Outside this period, the bare parts are much duller, with grey legs and feet.
The hunched shape of this heron is commonly seen along the coasts of these islands.
Both sexes are similar.
The immature has brown plumage, with dark streaks on breast, dark crown and greyish back.
It feeds primarily on crabs and small fish, taken in tide-pools, and lizards caught among the rocks. It also takes insects, prawns and some small birds, their eggs and their chicks too.
It perches on tree roots in mangroves, from which it dives into the water to catch preys. It also crouches before to stab at prey, both in water and on land.
The Galapagos Heron is usually solitary and very territorial. It chases away the intruders while it raises its short crest.
During the breeding season, the male gives advertising calls. It performs aerial displays, by circling in the air, and by chasing too, in order to attract a mate.
Both sexes stretch, bow and coo, about one metre from each other. Mutual preening is also reported.
But generally, the displays of the Galapagos Heron are less elaborate, with less aerial displays than in closely related species. They are monogamous.
The female usually lays 1-3 eggs, and both adults incubate during 21-22 days. The young birds fledge 34-35 days after hatching, and they are independent two weeks later.
This species produces up to three clutches per season.
PROTECTION / THREATS / STATUS:
The Galapagos Heron is common on the Galapagos Islands, but the species will be threatened in the future by destruction of mangroves for shrimp farming expansion.
But currently, the Galapagos Heron is not globally threatened.
RANGE:
The Galapagos Heron is endemic to the Galapagos Islands, and it occurs on all islands.
HABITAT:
The Galapagos Heron frequents intertidal areas and mangrove trees. It can be seen on lava shorelines, under lava outcrops and on rocky shores. Its cryptic plumage makes the bird difficult to find.
CALLS ANS SONGS:
The Galapagos Heron gives harsh alarm calls “keyow” or “keuk”. In territorial defence, it utters raspy calls. During the courtship displays, the male gives some “skow” to attract females. Both sexes give “cooing” during the ritual displays.
BEHAVIOUR IN THE WILD:
Unlike other Butorides species which feed in dense swamps and marshes, the Galapagos Heron forages in open shoreline.
But like all the Ardeidae species, it feeds by standing motionless or walking very slowly at water edge. It moves frequently from a feeding area to another one according to the tidal flux, through a wide intertidal zone.
The Galapagos Heron is mainly sedentary and moves only for foraging and mating.
Like numerous island species, it tends to fly very little and prefers to walk. But once in the air, it performs low and direct flight, and over short distances.
REPRODUCTION OF THIS SPECIES:
The Galapagos Heron can breed throughout the year, usually after heavy rainfalls, and mainly between September and March.
Both sexes build a nest with twigs, and the nest-building takes up to two weeks. They nest solitary, except in areas with abundant food sources. In this case, two or three nests can be seen in close proximity.
The nest is placed close to the ground within one metre, in mangroves, bushes or under rocks.
