Order: Ardeiformes - Family: Ardeidae
The Rufescent Tiger-Heron is a bird of solitary habits. Away one from the other, they keep within their limits and do not interfere. With the arrival of the breeding season two Tiger-Herons together may be a promising signal. They nest up in trees solitarily. This characteristic differentiates them from other herons, such as the Great and Snowy Egrets and the Cocoi Heron, which do nest in mixed heronries.
|© Norberto Oste||© Norberto Oste|
|In August 2010 this pair of Tiger-Herons was spotted in the nest. The previous instances: courtship, nest building and mating were not observed.|
The nest was spotted on 21st of August. Bearing in mind that incubation takes some thirty days, hatching could be expected by middle of September. On 17th of September an adult was sitting on the eggs but there was something unusual. It was not lying passively as usual. Something seemed to be pricking it from below. After a long wait the adult exposed two small white balls only for a short time and covered them again to warm them. Other observers saw the two chicks and a third egg still unhatched. This is not weird since there are species that begin incubation as eggs are laid. So chicks are born sequentially. This is known as asynchronous hatching. In the case of herons egg laying is every two days, time needed for the egg to form.
The nest is the world of the heron chicks during two months till they begin to fly. Parents' care is more dedicated at the beginning when siblings need to be fed and to be warmed. Once this stage is over their development is very quick and there is an increasing separation from the siblings. Lack of space obliges parents to watch the chicks from a nearby branch and when they are more mature they are left alone in the nest. Chicks' diet consisted of fish brought from the river. The adult regurgitated pieces of semidigested fish in the nest. As newly hatched they could not cope with the piece so they poked it with the bill. Very soon they were able to swallow it whole. There was a struggle to get hold of the piece, but no violence. There were no squabbles. Nor a fierce competition among siblings. In herons larger siblings usually attack the smallest one with bouts of pecks or push it out of the nest, which inevitably ends up in the chick's death. This was not the case but the smallest chick got rather behind the other two, which made us fear the worst. Luckily it caught up with the rest after a month.
Daily life goes by in silence. In solitary nesting this is the way to pass unnoticed. This is another difference with other herons which breed in colonies, where chicks are very noisy. One of the chores is to keep the nest stable. Three small nestlings moving around, an adult dodging them and the branch moved by the wind contribute to loosen the structure. So, they need to relocate, readjust or add more new material. The chicks watch their parents and imitate the actions.
|© Carlos Gonzalez L.||© Carlos Gonzalez L.|
Cleaning and hygiene go hand in hand. Parents keep the nest clean. Any infestation muy result fatal when chicks are small and fragile. They throw literally every bit of food over board. As far as the chicks are concerned they poop out of the nest. On the edge of the nest they point their rear parts high to expel fecal matter as far as possible.
|© Carlos Gonzalez Ledo||© Carlos Gonzalez Ledo|
Stretching legs, wings and neck is a way to exercise and strengthen the muscles which must be fully functional in a short time. In my opinion these stretchings also help to free feathers. Feathers grow enclosed in tubules which when torn from tip to base let the shafts unwrap.
|© Carlos Gonzalez Ledo||Feathers unwrapping out of the tubules
© Silvia Vitale
|© Carlos Gonzalez Ledo|
|Rufescent Tiger-Heron Tigrisoma lineatum Breeding of Rufescent Tiger-Heron in September 2010 © Roberto Ares|