Birds- Nesting Styles
BIRDS – NESTING STYLES
NIDICOLOUS and NIDIFUGOUS BIRDS
Birds do not live in nests all the time. In fact it does not live there except for incubating their young ones. Being (Diurnal- active by day) they go in search of food in the day and roost in a convenient spot in the night mostly perching on a tree branch. “BIRD’S HOUSE IS CALLED A NEST” IS A WRONG CONCEPT! Unfortunately we do not have much control on the text books that gets published. This is similar to the statement “Cauliflower is a FLOWER”, which is again is a wrong concept. If Cauliflower is a flower, should it not have the other parts of a flower, like petals, sepals, anthers etc. ? Technically cauliflower is undeveloped flower buds. It does give separate yellow coloured flower when it matures, rising from the middle portion in a long stalk. Birds build nest only for BREEDING young ones. Nest building is more through instinct and the material used by different birds differ and the styles of nest are also different. It is possible to identify a bird by observing its nest. Some like TAILOR BIRD (Orthotomus sutorius) stitch leaves. “Tailorbirds get their name from the way their nest is constructed. The edges of a large leaf are pierced and sewn together with plant fibre or spider’s web to make a cradle in which the actual grass nest is built. ”
When and how do birds build nest?
Most animals, even the GREGARIOUS(living in loosely organised groups and flocks includes humans too) ones, do not intentionally recognise its opposite sex except during breeding season. Emotional attachment is unique and well developed in human beings to the extent of taking care of the Chid and old. (With the abnormal increase in old age homes and crime against the aged, perhaps, we seem to be e loosing this emotional attachment. Can we afford to blame evolution?) Birds are not an exception even those that live in flocks. Each bird has a specific breeding season when the male and female bird pairs. The pairing lasts at least for one season in most cases as the parents take care of building nest and caring the siblings. In some cases such as ruby-throated humming birds, the emotional relationship lasts only till mating and after that the male goes away. Birds do not form emotional relationships like humans do, and their main drive for forming a pair bond is to produce offspring rather than for any emotional fulfilment. For all birds, the odds of producing surviving offspring are increased with a strong, healthy mate, which is why birds have different to find the most suitable partner.
As a RULE ,
“Birds that build nests on trees and lay eggs, hatch to give NAKED CHICKS, and fed by parent till they grow feathers and are capable of flying. ”
“Birds that build nests on ground and lay eggs , hatch to give fully grown chicks capable of walking and feeding themselves immediately after hatching”
BASED on THE NESTING SITE, BIRDS ARE CLASSIFIED AS
- NIDICOLOUS (ni·dic·o·lous(n-dk-ls)) BIRDS and
- NIDIFUGOUS BIRDS
- NIDICOLOUS birds remain in the nest for a time after hatching. The hatchlings are born without feathers.
- birds leave the nest shortly after hatching. They are born after feathers have grown on them.
Let us know about them in detail
In simple words, “the birds that are born on nests in trees are NAKED, BLIND, almost immobile and helpless. These baby birds (hatchlings) are without feathers. These are called Nidicolous birds”. Technically such birds are also called as ALTRICIAL meaning :
|A young bird or other animal, hatched or born in an undeveloped state and requiring care and feeding by the parents. Look at the photograph, the hatchlings are naked, blind, almost immobile and helpless. They have to be fed by their parents till feathers grow and they could fly and feed themselves. This weaning period may be about two weeks or more. Usually the birds in most cases are monogamous at least for one season so that both the parents look after their young ones! They build nests using different kind of materials including threads and cobwebs. Threads are used for stitching leaves in the case of TAILOR BIRDS and cobwebs protect the nest from ants. The nests are meant for one season only. After the breeding and when the fledglings fly away, birds abandon the nest. In the next season, they build another one to raise their young ones with the same partner or a different partner. Then they lay the eggs and incubate for about 18 to 22 days. Then the hatchlings emerge by opening the egg using the so called egg tooth situated on their beak. In the case of Nidicolous or Altricial birds have to be fed by their parents. The chicks open their mouth (beak) wide whenever the nest is disturbed by instinct. SOME EXAMPLES OF NIDICOLOUS NEST and EGGS
Their parents feed them for almost two weeks or more. They push the food, like caterpillars or other insects down their throat. Refer to the photos for details. NIDIFUGOUS BIRDS – ni·dif·u·gous – (n-dfy-gs):
These birds’ nests are found on the ground or on water. The eggs are laid on the nest or just a cavity on the ground lined with down feathers. When the hatchlings come out they are covered with downy feathers. An interesting feature is the camouflage they use for the colour of their eggs as well as downy feathers so that it is difficult to spot them even by their predators. These chicks can run about and feed on their own with in minutes of their hatching. The wet downy feathers dry off very fast. Perhaps the mother birds eat away the egg shells to conserve calcium and to prevent ants and flies disturbing them. Birds hatched on the ground need more protection than their counterparts hatched on nest in trees or bushes. They need protection from their enemies both on the ground and air. They also run the risk of being trodden on by larger animals. Two things primarily protect these young hatchlings. Ø Their downy feathers are usually camouflaged to blend with their background so that it is difficult to see them. Ø They freeze perfectly still at the first sign of danger, instead of flying away and exposing themselves fully. When they freeze it is really difficult to find them. You may see their breathing movement if you observe carefully. Refer to the photographs of Red Watled Lap wings chicks and eggs. Young chicks are protected from their enemies through instinct. Their parents also teach them by example that some animals are dangerous for them. Example of NIDIFUGOUS BIRDS, Nest and eggs
Article by Mr. R Venkata Ramanan. Chennai based educational consultant. See linkedIn profile. R Venkata Ramanan