Every visit to the jungle has something new to teach us, for every inhabitant of the jungle portrays the most indispensable skill of life - 'Survival'. For survival, these inhabitants need to protect themselves and their offsprings by exhibiting a high degree of parenting skills. From the myriad jungle visits, the one that I have narrated below inspired me to learn and research more on the parenting behavior in birds.
Like any other ardent birder, I was ready to observe the roosting of the birds in and around my house, which is situated at the foot of the Sholur Hill of the Nilgiris Biosphere Reserve. The forest in this area is a mix of shrub and bamboo vegetation and I had to carefully select a spot that gives me a good view of the landscape.
Having stayed in this place for a while, I have become familiar to the various bird species that visits regularly. For instance, to the east corner of the house, is a banyan tree which hosts a monstrous nest of the Crested Serpent Hawk Eagle and one can hear its offsprings giving out loud calls once a while; to the west of the house, I had often seen a pair of Brown Headed Barbets, merrily flying amidst the confused branches of the silver oak trees. From the corner of my eye, I had noticed a small bird, displaying acrobatic skills between the twigs of branches, stealing away cherry fruits, which were evidently the Hanging Vernal Parrots. To the south of the house were several wagtail nests. The northern side has rich bird life which includes - the Copper Smith Barbet, Asian Leaf Bird, Shrike, Starling, Green Bee-eater, Babblers, Scaly-Breasted Munia, Thrush, Spotted Owlet, Jungle Fowl, Oriole and Minivets. To extreme north of the house, I had also witnessed two pairs of Yellow Wattled Lapwings, guarding their nests.
It must have been around 18.00 Hrs, when I heard continuous cries from the Lapwing. These birds nest either on bare ground or in short vegetation. I noticed few men passing by the area where these birds had their nests. Slowly, the men walked away not disturbing the birds; the alarm calls subsided and I went about with my business. Twenty minutes later, I was writing my notes on the observation made during the day. I was so lost in writing, that I almost did not hear the alarm calls from these birds again. Only after the fifth or the sixth alarm call, I reluctantly abandoned what I was doing to see what was happening in front of me. It was only then I realized that there were no human disturbances this time and surely something was lurking around, as these birds were making continuous and high pitched alarm calls. Almost three minutes passed and I still could not spot anything. It was also difficult to understand what was disturbing these birds for two reasons - one it was quite far and secondly, the sun light was slowly fading away, which made it unnavigable for the human eyes. Suddenly, I saw something crawling in the middle of the bushes, making its way to the nests - it was a snake. From the size and the appearance, I realized it was a Rate Snake. The lapwings had sensed the danger and what happened in the next few minutes, clearly showcased the intricate design of nature - the parental instincts.
The male bird stood right in front of the snake, while the female stood diagonal to the male bird, possibly standing as a back up. The male bird went too close to the snake and spread its wings wide apart. He altered his stance, resting all his weight on one leg and rapidly fluttered his wings back and forth. Suddenly, the female bird took off from the ground, flying too low, with her loud alarm calls, trying to strike the snake on its head. The snake lifted its hood for a possible attack and I thought the parents had lost the battle. As though, they had well- rehearsed this scene a zillion times, the parent birds, came together very close to the snake, both with their wings wide open and the female, suddenly took off again and flew to the rear side of the snake. With the male distracting the snake, the female started attacking the snake, leaving quick pokes on the reptile's thick scales. This continued for few minutes and the snake had to finally let go off the hunt. The parent birds, though tired from the ordeal, ensured they did not move their glance from the serpent that was slithering away.
It took a while for my heartbeats to come back to normal. What I had witnessed was a remarkable chain of survival techniques deployed by these birds to protect their young. After experiencing this incident, I decided to spend the next few months to study the parental care in birds.
It is always fascinating to find bird nests, not just because of the excitement of locating something that is supposed to be hidden and remain a secret, or because these nests contain tiny, fragile shells that hold the future of avian life. Rather, the nests themselves are captivating - meticulous construction in hard-to-reach places, both sturdy and cushioning, able to withstand the elements, forged from materials scavenged from who-knows where and woven by these birds, who have nothing more than a beak and a pair of feet.
Three questions always haunted my mind - How do these birds chose the nest supplies? What factors do they take into consideration before building their nests? How do they raise their young to the point of independence?
Avian builders do not pick their supplies at random. Evolution has educated each species about the benefits of choosing some materials while ignoring others; because habitats will always be different, most species find a range of materials acceptable, rather than relying on one or two must-haves. Building supplies can be broadly classified to one of the three categories: vegetation, animal products and inorganic materials. The first category includes parts and various stages of plant growth, including rootlets, leaves and everything in between - bark, twigs, sticks, flowers etc. Also included in this category are mosses, seaweed, lichens and fungi. The second category includes animal products that may come from the birds themselves - feathers or mucus, as well as those that have been scavenged from elsewhere - particularly popular are bits of fur, hair and skin. Finally the third category encompasses inorganic items as diverse as mud, human trash and stones. Birds employ two basic techniques for nest construction and these determine which materials are suitable. The first technique is sculpting, a process by which birds remove material from an existing structure, ultimately leaving only a nesting cavity or scrape. The second is assembling, a process by which various materials are gathered and then joined together to create a place where eggs can be deposited. This category actually comprises a variety of techniques, such as weaving, interlocking, piling up and sticking together.
Birds must find a secure place to hatch their eggs. All sorts of predators hunt for eggs, since they are high in protein and nutrition. Although birds' eggs appear to be fragile, they are in fact extremely robust. The oval shape applies the same rules of engineering as an arched bridge; the convex surface can withstand considerable pressure without breaking. This is essential if the egg is not to crack under the weight of the sitting bird. For example, it takes 26 pounds of pressure to break a swan's egg and 120 pounds to smash the egg of an ostrich.
One of the most remarkable ploys of placing its eggs out of reach of most predators is demonstrated by the African palm-swift. It uses its own saliva to glue its nest, a little pad of feathers, to the vertical underside of a palm frond. The two eggs are also glued to the nest and the parents incubate them by turns, clinging to the nest.
The edible-nest swiftlets of South-East Asia make a most unusual nest - entirely from their own saliva. The swiftlets build their nests high up on the roofs of a cave. The hard basket-shaped cups are made of concentric rings of a protein-rich goo secreted during the breeding season by the male's enlarged salivary glands. He dribbles long sticky strands, using his beak as a shuttle to weave a cup-shaped bracket onto the cave wall.
Birds employ the most astonishing strategies to conceal their young from predators. The female hornbill seals herself into the nest and stays inside the tree cavity throughout incubation, leaving only a tiny aperture. The female bird also spends few days testing the male's ability to provide her with food before she committed herself to laying.
The final ingredients that some birds may ‘add’ to their nests are nearby animals. Generally, the other animals fall into two categories: other breeding birds and arthropods. Colonial breeders such as seabirds and finches take advantage of the safety-in-numbers effect: A larger number of watchful eyes allow quicker detection of predators, and a higher number of nesting neighbors increases the likelihood that someone else’s nest will be predated. For other birds, it is advantageous to nest near another species altogether, one that is more vigilant and/or more dangerous-particularly, birds of prey. Sometimes this means risking predation, but the increase in fledging rates at these extra-guarded nests is worth the gamble. Termites, caterpillars, spiders, ants and bees may also be closely associated with bird nests. In some cases, the birds nest within structures created by these animals - sunbirds in Africa nest within spider webs, while kingfishers and parrots nest inside arboreal termite nests. White-browed sparrow-weavers do nothing to discourage paper wasps from nesting on the underside of their nests. As is the case with most of these bird-arthropod relationships, the birds benefit from the proximity of neighbors who provide constant protection from predators; in some cases, they might occasionally offer a tasty snack, as well!
A very unusual cooperation in breeding has evolved between members of two different bird species. The small red-breasted goose breeding on the Siberian tundra is extremely vulnerable to predation by arctic foxes. The geese have established a working relationship with another inhabitant of the arctic tundra. The peregrine falcon nests on the tundra at the same time and this small but fierce bird of prey is able to ward off the hungry arctic fox. Red-breasted geese nests in tight knots around the nests of peregrine falcons, benefitting from the protection that the bird of prey offers. The peregrine does not prey on the geese and their young. In return, the loud alarm calls of the geese alert the peregrine, which has its own chicks to protect. The swooping vicious attacks of the peregrine falcon soon deter the fox from coming any nearer.
There are other birds that dispense with every convention of home making and parenthood, and resort to cunning to raise their families. These are the 'brood parasites', birds which never build their own nests and instead lays their eggs in the nest of another species, leaving those parents to care for its young.The cuckoo is the best known brood parasite, an expert in the art of cruel deception. Its strategy involves stealth, surprise and speed. The mother removes one egg laid by the host mother, lays her own and flies off with the host egg in her bill. The whole process takes barely ten seconds. Cuckoos parasitize the nests of a large variety of bird species and carefully mimic the color and pattern of their own eggs to match that of their hosts. Each female cuckoo specializes on one particular host species. How the cuckoo manages to lay eggs to imitate each host's eggs so accurately is one of nature's main mysteries.
The greater honeyguide in Kenya is another parasite. It lays its eggs in the nests of the red-throated bee-eater; but its chicks, when they hatch, have a deadly advantage. They are armed with a murderous hook-tipped bill. The chicks of the red-throated bee-eater die under the vicious attacks of the honeyguide chick within the first few days of hatching. The murder weapon then drops off, its purpose achieved. The foster parents now devote all their energy towards feeding the killer of their own young.
Birds must leave their nests in time - provided they have survived the many dangers of home life. There is a great deal of variation in how independent the young are once they hatch from the egg. The only birds able to fend for themselves from the moment they hatch are the Australian Brush Turkey or mound-builders. Birds hatch at very different stages of development. In general, the shorter their incubation time, the less developed the young are when they break out of their shells. Altricial species, which includes most song birds, hatch at a very early stage. Naked, blind and helpless, they depend on their parents for food and warmth until they are ready to leave the nest. Precocial young are quite different: they hatch with functioning eyes and a covering of fluffing down. Within minutes of hatching, they are on the move and soon can feed themselves. This type of young are produced by ground-nesting birds such as Waders, Ostriches, Waterfowls. Between these two categories are intermediate species that do not fit either category. For example, gulls and terns hatch with a covering of down and are able to walk, but stay at the nest to be fed by their parents.
After their young have hatched, adult birds face a monumental task to keep their growing family fed. Every day, a pair of thrushes may make several hundred return flights with bill full of food, while smaller birds such as tits or chickadees, can make two thousand or more trips daily. Birds of Prey make fewer journeys to and from the nest, but depending on their size, they can usually carry large prey in their talons. Sea birds often swallow their food, making it easier to transport on the long flight back to the nest. During this journey the food is partly digested, so the parents feed its young by regurgitating the remains. Pigeons have a unique solution: they produce a fatty secretion called crop milk, which their young drink by reaching into their throats.
The Raptor Resource Project brought the internet's first bird cam, (popularly knows as Decorah Iowa Eagle Cam Project), which quickly became the busiest corporate site in the world. Over 200,000 million people from 184 countries watched the live telecast of the eagle family.
When I got in touch with couple of my birder friends, Rina LaBelle and Gordon LaBelle, who have been closely observing the Bald Eagle site, they had a lot to say about the parenting instincts. They quote, “We have watched the Bald Eagle site on the webcam and in the year 2009, we found a Bald Eagle site that we visited every 7-10 days. The Bald Eagles chose their nests depending on the food supply, which is predominantly fish. The Bald Eagles we have seen on the webcam had their nest close to a fishery and the river. They also hunt for rabbits, squirrels and even small deers. The nests are very big and they constantly work to maintain the nest with twigs and branches. Depending on the age of the parents and their previous experience, the offsprings will have a fewer or better chance on survival. On the webcam the male had a lot of experience with a previous female, who suddenly died during a winter storm. Though the Bald Eagles chose their partner for life, nature found its course and in the next season the male found a young, strong but inexperienced female; Because this young female was inexperienced she had no clue what to do with the little fuss balls, but the male showed her how to deal with them and feed them. Soon she got the hang of it and now she has been doing it for three years in a row, very successfully with three eggs every season”.
A year or so later, I sat in the very same spot from where I had seen the Lapwing defending against the Rat Snake. This time, I saw five pairs of Lapwings. Still, the preponderance of nest-builders indicates that it is well worth the birds’ time and effort to continue with the age-old practice of scouting out clumps of lichen and tufts of shed fur, all in the endeavor of putting together the perfect nest in which to raise a brood. Procreation is what I saw this time.