Vultures constitute an important component of the ecosystem. Being carrion feeders, they perform an important task as finishers in the ecosystem in returning human and animal corpses into their elemental forms back into the system and thus play a significant role as cleaners or disposers in the nature. They are capable of stripping carcasses free of all flesh, soft and hard tissues such as tendons, cartilages, softer bones, skins, hairs and keratins with their sharp claws and beaks; and due to special enzymes in their stomach are capable of digesting them. Different species of vultures are reported from the Indian subcontinent and unfortunately the populations of most of these ecologically important species are showing serious signs of decline across most of their natural ranges. Some of the factors that have contributed towards the rapid decline of the populations of different species of vultures across the subcontinent include: loss of habitats and habitat fragmentations; removal of old and big trees in and around city fringes, city parks and city gardens causing loss of suitable nesting sites; rapid and unplanned urbanization drive to cater to the growing human populations in the cities and towns; unprecedented boom of real estate business and infrastructural developments causing the loss of green spaces within and around the major city areas, the added areas and their subsequent extensions and in the greater metropolitan areas including district towns and municipalities; rapid, unrestricted, unplanned and unmonitored growth of both legal as well as illegal industrial units within city limits and adjacent areas causing pollution of the local environment; severe anthropogenic pressures in the remaining open spaces at the city fringes due to human encroachments and establishments of slums and shanties; communicable diseases among vulture populations; and last but not the least, poisoning of the animal carcasses on which these birds feed as their primary food sources both intentionally as well as accidentally. Furthermore, pesticide poisoning of the birds have also been reported from several parts of the subcontinent.
Subsequent scientific studies established that diclofenac, an anti-inflammatory drug commonly administered to the Indian livestock for the treatment of wounds and inflammations, as one of the potent chemicals that have been killing and decimating the vulture populations in India through the process of biomagnification. The leading cause of death through poisoning by the drug among vultures is through drastic renal failures. The species that have been worst impacted are the Indian vulture (Gyps indicus Scopoli), the white-rumped vulture (Gyps bengalensis Gmelin) and the slender-billed vulture (Gyps tenuirostris Hodgson (in Gray)); that were reduced from stable populations of several millions to just a few thousands over the span of two-three decades.
In several parts of their former ranges a decline between >70-85% to < 97-99% in their wild populations have been reported raising an important concern for their threats to extinction in the next 20-25 years. Unfortunately, the Indian vulture, the slender-billed vulture and the white-rumped vultures are all now placed under the category of critically endangered by the IUCN; while the Egyptian vulture (Neophron percnopterus Linnaeus) is currently considered to be endangered. The only species that is evaluated to be near threatened in the wild is the famous Himalayan vulture or better known as the Himalayan griffon vulture (Gyps himalayensis Hume) that is restricted to the Himalayas and the Tibetan plateau and is not dependent too heavily upon livestock carcass as their principal dietary source; and the Eurasian griffon (Gyps fulvus Hablizil) which is under the least concern category. The facts clearly indicate that the vultures belonging to the genus Gyps are most readily impacted and also these species are distributed predominantly in the river valleys, great northern and western plain lands and the plateau region of the subcontinent with significant agronomic activities and substantial livestock populations. Hence the biomagnification poisoning through diclofenac has been identified as one of the most devastating factors decimating the vulture populations in the Indian subcontinent in addition to several other anthropogenic factors mentioned above.
Several vulture rehabilitation, breeding and reintroduction centers have been established in India being alarmed with the sharp decline of the vulture populations and a few more are coming or are being proposed. However, their numbers are too meager compared to the need from the context of species revival. Some success has been documented in the breeding, rearing and reintroduction of different vulture species in the wild in various parts of their former home ranges; however, much needed to be done. Steps have been taken in removing diclofenac as the preferred veterinary drug by the cattle handlers and livestock operators with other alternatives having much lower impacts on the vulture populations has been recommended and/or prescribed. But the drug is continued to be used in small to moderate numbers till date across the home range of the vultures. Lack of education and awareness; as also lack of care and empathy for the long term sustainability of the local ecosystem and environment by agricultural workers, cattle handlers and livestock operators have been another serious concern that needs to be addressed sincerely by the vulture conservation agencies. It will be necessary to completely ban this drug from the livestock industry and strong monitoring and surveillance will be necessary to evaluate the wild populations of vultures in the coming decades. Unless a comprehensive conservation, rehabilitation and reintroduction policy is adopted with strong legislative measures and effective wildlife management strategy is implemented and practiced in saving the Indian vultures, their future looks extremely grim and vulnerable with dangers of extinction in the wild.
Article contributed by: Saikat Kumar Basu
The rhinoceros hornbill (Buceros rhinoceros) is a most unusual looking bird found primarily in the rain forests of Sumatra, Borneo, Java, Singapore, the Malay Peninsula and southern Thailand. Its large yellow-orange hornlike casque, curving upward from between its eyes as an extension of its beak, makes it immediately clear why this species of hornbill is associated with a rhinoceros. As one of the largest hornbills, adults weigh up to 3kg and are typically between 91 and 122 cm long. They have a lifespan of thirty-five years or more in captivity and there is little difference in appearance between the male and female of the species, other than the male having orange or red irises, and the female’s irises being whitish in color.
While the casque may be shaded in orange and yellow, the beak of the rhinoceros hornbill is mostly white. When in flight, the rhinoceros hornbill’s black wings curve around gracefully towards its head, while it’s white tail feathers with a perfect semi-circle of black spreads out like a fan. As omnivores, these fascinating birds eat fruit, insects, rodents, small reptiles and even smaller birds.
During the breeding period the female rhinoceros hornbill is completely dependent on her mate as she incubates the eggs and starts raising their chicks. Upon finding a suitable cavity in a tree trunk, the female lays one or two eggs while the male collects mud which the pair will mix with food and feces to close up the entrance to the nest. They leave a small hole in the newly made wall for the male to pass food through for the female and later for the chicks. The female also defecates through the hole to avoid soiling the nesting cavity. Around thirty days after the eggs hatch the female breaks through the wall and seals it behind her. Both parents continue feeding the chicks through a small hole until they are able to break through the wall on their own, at which point they are ready to fly.
Rhinoceros hornbills are not considered to be endangered at present, however deforestation is a problem which could impact populations in the wild in the future. Moreover, these birds are hunted as food, and ornaments are made out of their casques. Members of the public can play a part in conserving rhinoceros hornbills and other animals by refusing to buy ornaments or other products made from their body parts.
Irrigation canals constitute an important nesting site for several aquatic bird species and have slowly transformed into an excellent natural habitat over the passing decades. Several wild aquatic bird species such as Canada geese (Branta canadensis L.; Fig 1) and mallard ducks (Anas platyrhynchos L.; Fig 2) have in particular found such canals as important nesting, resting, breeding and foraging sites across the Canadian Prairies. The lush vegetation that accompanies irrigation canals traversing across the municipalities and rural districts provides excellent nesting and hiding sites for the breeding aquatic species; while the water in the irrigation canal serves as important foraging ground. The dense vegetation protects the nests, eggs and nestlings from a host of predators making their breeding a success story across the Prairies.
The security of the bushes and the abundant supply of food, water, foraging and nesting resources have made certain stretches of the intricate network of irrigation canal a bold success story for several such aquatic bird species. During the breeding season large flocks are seen to be approaching the canal nesting sites in good numbers both by the mallards (Fig 3) and the Canada geese (Fig 4). Although a number of predatory birds and mammals do also nest in nearby trees (Fig 4) and bushes and woods to take advantage of the yearly bounty; particularly the highly vulnerable nestlings and fledglings such as the young and defenseless ducklings and goslings.
However, the greater number and close guards by the caring parents do not actually impact the species population and is in particular nature’s own monitoring in keeping the population under check (Figs 5-6). Hence, in a broader term a healthy and thriving population of the ducks and the geese actually positively contributes towards the stable population of the predatory birds and mammals too; further extending the success of the irrigation canals to other wildlife species. In addition to the mallards and Canada geese or black geese, other species of ducks and geese (such as the grey and white geese) are also known to take advantage of the refuge of the irrigation canal habitats along their annual migration routes. Several other non-aquatic bird species like the different black birds (Fig 5) that inhabit the ecotones between land and water also take advantage of the natural habitats produced by the irrigation canals.
Hence, the construction and development of the large network of irrigation canals across the Prairies have been an excellent natural resource that has been helping in building the population of local birds and in directly contributing towards establishing a sustainable environment. However, it will be important in future to do extensive bird surveys in and adjacent to such artificial habitats for monitoring the bird population and in better understanding the nature and behaviors of different species that have been intelligently using such available resources to their advantage. It is often interesting to note that anthropogenic activities that impact wildlife species so negatively could also have positive impacts in some other ways. It will be therefore important for us to learn from the experience and develop our future technologies in a pro-nature or environment friendly fashion so that we could effectively curb our foot prints on the nature and also successfully reduce our impacts on the population of different wild species of birds.
Prime nesting and foraging habitats of Canada geese adjoining irrigation canals are pictured below (Fig 7-8).
Article contributed by Saikat Kumar Basu
Swooping through the air in flocks of up to a million birds, starlings have long been a feature of rural life in the United Kingdom. A flock of starlings in flight looks like a dark cloud constantly changing shape as they expand and contract randomly with no apparent leader. This bustle of activity usually takes place near their nesting grounds, in both rural and urban settings, and while some see them as pests, primarily because such large flocks of birds produce large amounts of droppings which can become toxic, starlings are considered to be part of the UK’s natural heritage. So, a recent report by the RSPB based on the annual Big Garden Birdwatch showing that the starling population in the UK had dropped by 80 percent since 1979, with almost a third disappearing in the past decade, is viewed as a cause for concern. Research further reveals that, since 1980, up to 40 million starlings have vanished from European Union countries, translating into a rate of 150 birds an hour.
As primarily insectivorous birds, but eating grains, fruit, and seeds if available, starlings keep insect numbers in check. They have an interesting feeding habit that ensures all in the flock are fed. As they forage amongst short-cropped grasses, birds from the back will continually fly to the front so eventually every bird will have had an opportunity to lead the flock and be first in line to probe the ground for insects. They are also very successful at snatching insects in mid-flight. Unpaired males build nest with which to attract a potential mate, and they often decorate the nest with flowers and green foliage. Upon accepting a mate, the female promptly discards the decorations. Males sing as they construct their nests and will launch into their full repertoire if a female approaches the nest. With starlings nesting quite closely together in large numbers, courting season is a lively time.
The RSPB has launched a research project to try and determine the cause of the drastic decline and formulate a conservation plan. RSPB researchers will be working in conjunction with farmers in Gloucestershire and Somerset to examine whether there are sufficient nesting sites and food sources for starlings resident in livestock areas. Conservation director for the RSPB, Martin Harper, noted that they hope the research will yield the information necessary to provide the starlings with a secure future through the development of practical and cost effective solutions for farmers and land managers to implement.
Believed to have been domesticated in the Mediterranean region up to 5,000 years ago, pigeons are providing new insight into the role of genetics in the development of physical traits. A study being carried out by the University of Utah, in the United States, has revealed that there is an enormous amount of diversity among these birds, with more than 350 breeds of pigeons differing in body size, color, patterning, beak size and shape, posture, skeletal structure, vocalizations, flight behavior and feather placement. Enlisting the help of pigeon breeders around the world, the study focused on the visible traits and genetic relationships of 361 pigeons representing 70 domestic breeds, as well as populations on the Isle of Skye in Scotland and Salt Lake City, Utah.
Michael Shapiro, assistant professor of biology at the University of Utah, and the senior author of the study which was published in the journal Current Biology earlier this year, noted that it was observed during the study that similar traits can be found in birds that are distantly related, and conversely, closely related birds can at times look quite different. Among the examples cited to support the study is the fact that both the English trumpeter pigeon and the German owl pigeon have crested head feathers despite not being closely related. Furthermore, English trumpeters have feathers on their feet similar to that of English pouters, and yet the two species are not closely related, as is the case of the short beaks shared by the African owl pigeon and the Budapest short-faced tumbler. On the other hand, the closely related African owl and German owl pigeon have short beaks in common, but the African owl has plain head feathers, with the German owl sporting a head crest.
Other interesting findings of the study include the fact that free-living pigeons, such as those commonly found in cities, particularly around statues, carry the DNA of racing pigeons. Some of the traits found in pigeons are likely as a result of selective breeding, as is the case with other domesticated animals, such as dogs, but many of the traits found in pigeons are as a result of adapting to their environment. Shapiro pointed out that many different animals use the same genes in order to build similar body structures, and if scientists can understand which genes are behind normal diversity in the wild through the study of pigeons, this knowledge could ultimately provide insight into diversity in humans, including human disease.