Ibisring

Ibisring has the honour to publicate the thesis and publications of Dr. Khem Chand Soni. He has studied the population, foraging, roosting and breeding activities of the Oriental black ibis inhabiting the arid zone of Rajasthan (India).

It's always possible to contact Dr. Khem Chand Soni for more information: kcsibis@yahoo.com or (91)9414466107.

• You can download the full thesis here: The_Black_Ibis_Thesis.pdf
• You can download an article about the effects of environmental stress on this ibis species here (published: Environmental degradation and management. Vol.2, 2006, 49-56): Effects_Environmental_Stress.pdf
• You can download an article about the role of this ibis species in crop protection in agriculture here (published: Flora and fauna 13(2): 371-374): Role_Of_The_Black_Ibis.pdf

The following summary is composed by Koen Thijs (koen@ibisring.com) for Ibisring.

Introduction

There are two races of the species Pseudibis papillosa: Black ibis (papillosa) and White shouldered ibis (davisoni). The eastern subspecies, the White shouldered ibis was formerly found throughout Southeast Asia from Burma, Thailand, Malaysia, Cambodia, Laos, Vietnam and north to Yunnan and China. Now-a-days, it is considered as threatened to near extinction. However, rediscovery of few individuals of White shouldered ibis in Vietnam, it is an helpful case to take up some intensive conservation measures to save the species from total extinction.

Fig. 1: An adult Black ibis showing black coat colour, characteristic triangular red wart and long curved bill.

The Indian Black ibis (Pseudibis papillosa Temminck) is one of the 23 ibis species of the world, and one of 33 avian species belonging to the family Threskiornithidae. It is a medium sized bird of about 68 cm length with a wing span of about 38 cm having a 16 to 19cm long tail. The adult bird has a triangular patch of red warts on the head and extending about 13 to 17 cm long down curved bill. It has an inner lesser wing covert with a white shoulder patch that is visible while the bird is in flight. The neck, mantle, lower back, rump and lower plumage are all brown. The scapulars and back feathers are bronze green. The tail is black and richly glazed with blue green. The wings are black, glazed blue and secondary feathers of wing are sometimes flecked with white. A large, brood patch of white runs along the leading edge of the wing on the lesser wing coverts to well below the carpal joints. Although prominent in flight, this features shows only a thin white line when the wings are closed. The short legs are hidden beneath the steel blue tail in flight. The tibia has feathering half way to the tarsus joint. The head, somewhat square shaped is black and distinctively capped with a triangular patch of warty red skin, absent in juveniles. The eye is orange red to bright red. The curved bill and the broad stubby feet are horn coloured. The iris, legs and feet turn bright red at the commencement of breeding. The male is slightly larger than the female.

Fig. 2: A pair of Black ibis depicting morphological differences in male and female. Note-Comparatively long bill and big size of the male Black Ibis.

Young birds are dark brown all over lacking red wart and have yellow iris with paler breasts. They lack the iridescent tinge on their feathers. The pale horn coloured bill is shorter than that of the adult. The Black ibis is generally a silent bird when feeding but is noisy at the evening roost. There, its call is loud and trumpet like. It is sounded particularly when the breeding season approaches, as the male birds advertise at nest sites prior to pair formation.

The Black ibis is wide spread in Indian subcontinent, occurring almost through out India, Pakistan, Nepal, Bangladesh, and China. The bird is popularly known as “farmer's friend” as it feeds on large number of insects injurious to crop. Not only this but also it is among a few ibises who inhabits dry areas. The Black ibis occupies a similar ecological niche in Asia, as does the Hadada ibis in Africa.

Habitat

The Black ibis needs a region where bird roosts or built there nests and a region from where it gets its food. In these study, the bird has been seen in:

• Waste water bodies: in these water bodies Chironomous larvae and many aquatic insects are found in abundance. The Black ibis preferably feeds on these insects.
• Municipal garbage dumping stations: in these areas the waste materials collected from the houses and public places are dumped. Earthworms, Spiders, Cockroach and Beetles develop here which are eaten by the Black ibis.
• Animal dead body dumping stations: climatic conditions in the survey area are very harsh. In winter the temperature falls below freezing point and in summer it reaches up to 50° C. It is also a drought prone area and regularly faces the great problem of drought. As a result of this, thousands of animals die. These animals are dumped in these areas. Maggots and Blow fly larvae develop in abundance at dumping station which is utilized by Black ibis as food.
• Agriculture farm houses: the study area covers some tube wells based agricultural farm houses and rain fall dependent fields. During rainy season the insect fauna flourish well. Black ibis preferably feeds on these insects.
• Sand dunes: large and regularly changing sand dunes are very common. Generally cattle's graze in the sand dunes for herbs and shrubs and they egested out dung in sand dunes. The dung contains cellulose and fibrous material which are digested by dung beetles. The Black ibis feeds on these beetles by probing their bills into holes below the semidry dung.

Fig. 3: A single Black ibis feeding on Beetles in the sand dunes.

• Grazing fields: worship and protection of birds and animals are important aspects of Indian culture. There are thousands of hectares of land for grazing the pet animals like cow, buffalow, ox, camel, goat etc. By aggregation of these animals in grazing fields, the dung gets accumulated. Hence, grazing fields are the rich source of dung beetles which are used as foraging materials by Black ibis.
• Forest areas: as per environmental policy of government of India some areas are protected as forests reserve. Acacia spp. is in abundance in forest reserve. There are numerous plants like neem (Azadirachta indica) or peepal (Ficus religiosa) on which ibis generally roost or nests. So ibises are generally not found in forest areas. But during rainy season insect fauna is very abundant in forest area which is an attraction to this bird.

Fig. 4: An adult Black ibis searching food in the forest area.

Feeding Ecology

Though majority of the Ibises characteristically feeds in and around water, some of them are not necessarily rely upon wetlands. The species of Ibises like Bald ibis (Geronticus eremita), Hadada ibis (Bostrychia hagedash) and Indian Black ibis (Pseudibis papillosa) are primarily terrestrial birds, but they also use aquatic habitats.

The ibis exhibited several kinds of feeding behaviours. Probing behaviour was found as the chief technique with more than 90% of the time applied. Standing fly-catching was uncommon and applied in an habitat which had a considerable amount of flies. Packing, a visual feeding technique was applied in all the habitats. Bill dragging, flipping, and foot raking were used rarely; depending upon the situation and type of prey. In sand dunes, the ibis used stepping and probing to dig out the beetles. Shallow probing was applied in all habitats.

Primarily the ibis found to feed on animal matter, but consumed plant matter depending upon opportunity. Its diet composition was determined by stomach content analysis, faecal pellet analysis and by field observation methods. The Black ibis was usually found to feed on Locust, Grasshoppers, Mantis, Dung beetles, Tiger beetles, Scrab beetles, Municipal garbage, Caterpillar, Spiders and Centipedes. Availability of food was affected by the seasonal changes. Therefore the duration of feeding was more in summer and rainy season as compared to winter season.

Roosting behaviour

In the study area, a total of 35 roosts sites were identified Out of the total 35 roost sites, 21 were found temporary whereas 14 were permanent. A total of 430 trees belonging to 14 species were recorded as roosting trees. Khejari Prosopis cineraria (40%), Neem Azadiracta indica (28%), Peepal Ficus religiosa (12%) and Saresh Albizzia lebbek (7%) were the principal roosting trees comprising 88% . The ibis selected live and unbroken canopies of the tall trees to roost. Though height was one of the considerations for roosting but only tall trees of Neem, Peepal, and Bargad with good canopy preferred for roosting. Thus a combination of height, canopy and DBH were found to influence the roosting of the Black ibis on trees.

Fig. 5: A Black ibis showing flight for roosting. One Black Ibis is already roosted on the Neem tree.

Flight formation of the arriving and departing birds was typically V-shaped with occasionally random pattern. At the study sites, a higher percentage of juveniles were noticed to arrive earlier than the adults to the roost site. It was observed that the juvenile birds followed the adults at the time of departure from the roosts in the morning. Birds were observed to pre-roost on the khejari tree near to roosting neem tree, on the top perch of building, and on the highest available perch, like TV-antenna, microwave tower, etc. Out of 100% roosted ibises only 86 % ibises followed pre-roosting. The ibis was mainly involved in preening and calling loudly while pre-roosting. Interactions among individuals were seldom. It was noticed that the roosting bird apparently change its position after arrival of all members on the roosting tree. Juvenile birds were seen in the lower canopy of the roosting trees, whereas adults were seen throughout all available perch sites at different heights. After entering the roosts, some individuals shifted from one perch to the other and sometimes made circular flight while re-entering the roosts. The circular flight was generally clockwise in almost all observations. Once sitting on the roost trees, the majority of individuals moved toward the inner canopies. The accumulation of faecal matter on the branches below the perched branches indicated the same perches were used repeatedly over several nights and possibly by the same individual. The ibis preened its shoulders, wings, belly, back, and tail before persisting rest.

Fig. 6: A group of eight Black ibises showing diurnal resting on the khejri (Prosopis cineraria) tree.

During breeding season, the female occupies the perch near to its future nesting site at the roosting tree and male bird occupies the top branch of that roosting tree. During rainy season the Black ibis preferred roosting in outskirt of rural and urban area due to availability of feeding material in grazing fields and agriculture farm houses. But in winter season, they shifted themselves to roosting sites close to human habitation and their number also increased per roosting tree due to aggregation as the bird had communal roosting.

Fig. 7: A flock of five adult Black ibises showing diurnal resting on the branches of dead tree.

During flight they followed a V-shape pattern and during flight in sky they also produced voice like klarr, klarr but with longer interval. During summer in mid day the ibises flew at high altitude along with Egyptian vulture and showed circular motion like Kite or Egyptian vulture.

Breeding biology

Total of 28 nest sites of the Black ibis were noted within the study area during the study period. Majority of the nest sites were located in the heart of rural and urban area and nearby feeding sites. But in rainy season the Black ibis preferred to nest in outskirt of rural and urban area. The Black ibis preferred nest sites at the trees in the club of number of tree species. Relatively densities of Neem (Azadirachta indica) and Peepal (Ficus religiosa) were significantly higher then other trees in the habitat of the Black ibis. All observed nests of the ibis were found to locate on the third sub-branch of the trees.

Fig. 8: Adult Black Ibis defending the nest from the House Crow.

In the month of March-April at the height of the breeding season the male Black Ibis acquired brighter red colour in a wart patch on head. The gullar pouches became visible. The Black ibises were quiet and staid, being tolerant of one another. They showed billing during courtship. Soon after “getting together” they started billing, rattling their long bills together and moving their head from side to side and up and down. After about a minute they paused to preen, but soon resumed their billing. This happened near the nesting site. Both the sexes were noticed to give soft call note, allopreen, hold bills of each other, shake each others bill, and made quick bill contacts. Among all the defined courtship behaviours, making call notes was the most commonly exercised behaviour by both the sexes mainly before they copulated.

Male ibises were seen shaking soft twigs of the trees in the presence of females on a roost and give loud calls like “klaaa klaaa”. On hearing the male; a direct flight of the female to the male was seen. Thus the pair formation initiated. Later on the male bird mounted the female. Mating was performed mainly at the nesting site during nidification. The male bird mounted the female bird during his visits to the nest with the nesting material. An average 4,3 matings occurred in a day.

A pair of the Black ibis was observed to examine one deserted nest. After mating, a female partner entered the nest and gave a loud call and later the nest was occupied. Hence it was considered that the preference of a nest selection was made by the female partner for that particular pair. Construction of a new nest was very rare, rather renovation of an old nest was seen as a priority. In case of conflict the aggressive male of a pair could succeed in acquiring nest site.

Role of male and female parents in incubating eggs and rearing the chicks was studied in ten breeding pairs. Changeover during incubation was found five times while it was eight times during rearing the chicks. The minimum changeover was 3 during incubation period and 5 during chick rearing period. Maximum changeovers took place in the morning and less in the evening and noon. Changeover did not take place in the night. The nest was made of sticks and leaves of local plants. The largest sticks were on the outer edge and the smallest in the center of the nest. The slightly depressed center of the nest was lined with leaves and grasses.

Average 9.3 days were spent for nidification. An avid female Black ibis laid an average 2.2 eggs in three days. Eggs of the Black ibis were ellipsoid in shape, plain and dull white with faint bluish tinge with a few dark bloody reddish spots. The average period of incubation was 29.8 days.

The average number of chick hatched was 1,8, while the chicks fledged was 1,6. The average of nestling period was 16,2 and fledgling period was 36. From pair formation to fledgling, one complete breeding cycle took 13-15 weeks of period.

Fig. 9: Nest of the Black Ibis showing one infertile egg along with the 16 days old nestling hatched from fertile egg.

Chicks hatched asynchronously. At hatching, the Black Ibis chick was altricial with close eyes. Most of its body had a sparse cover of creamy down feathers. The black down covered the head, dorsal and lateral areas of the neck. The bill was black while legs were uniformly pinkish white in colour. At on to four days, the chick was blind and having creamy coat of down feathers, black head and bill. It was unable to move. Four to eight days old chick was having open eyes. It was raising the body, and threatened the intruder by creating sound. The chick tried to stand erect on their week legs with the support of the bulging abdomen. The chick gave short note “cheek” at that time. The sheath of the remises and rectrizes began to grow. Feathers having cobalt blue pigment appeared on the back of 8-12 days old chick. Plumage began to turn darker, and chicks initiated stepping in the nest. The bill, legs, neck and wings also grew. At 12 – 16 days of age the nestling was having white spots on shoulders. The body parts further developed and the colour became brownish black. The beak of the chick was small, but decurved and legs were gray and enlarged especially at the joint between tibio-tarsus and tarso-metatarsus. The gular area turned greenish to whitish. The nestling started flapping the wings at the age of 16 to 20 days. The chicks were not guarded all the time during this stage. The body was covered by feathers along with the dark gray down in the head and neck region. The nestling became fledgling at this stage. The rate of increase in body weight declined at this stage due to loss in flapping the wings. Chicks were noticed more active, alert, and aggressive with full black plumage and brighter white shoulder patch. The fledgling continued to move around the nest.

Fig. 10: Spreaded wing of the chick of young Black Ibis showing further growth of feathers.

At 20-24 days of age, the young ibis excreted faecal matter outside its nest. The fledgling stood on the nest most of the day and begged for food from parents. Chicks were flapping their wings vigorously, walking on the nest and greeting parents at the time of their arrival. The young ibis of 24 to 28 days was fully feathered and the feathers began to unsheathe. At 28-32 days of age, the young Ibis lost sheathes of the feathers. The body parts continued to grow. The young ibis of 32-36 days of age climbed to the nest tree but returned to nest after some times. It moved about the nest and made the nest flat. The fledgling became more aggressive. Activities like preening and clearing the waste out of the nest were seen in the fledgling at 36-40 days of age. The nap area became brownish. The fledgling made short flight between the branches of nest tree at 40-44 days of age. At 44-48 days, the body parts of the fledgling continued to grow. It walked atop the tree. Parents fed fledgling out of the nest but on the nest tree. The fledging at 48-52 days of age was fully grown. It left the nest under safe guarding of the parents. Female guided the fledgling to the safe site out of the nest tree. During the chick's development, parents were found to feed 7-10 times a day by mouth to mouth packs. Chick's begging for the pack of a food were noted. They were darting the beak on parent's lower mandible. Whenever chicks failed to pack, they continued mock packing by thrusting their beaks in the direction of parent's bill. As hatching was asynchronized, competition among the different aged siblings was noted.

The fledgling returned to nest in the night. It deserted nest completely only after attaining 105 days of age. The identification was easy due to the absence of red wart on the head of the young. Triangular patch of red warts on the head completely developed in 18 months. Losses from nests with eggs were greater than losses of nests with nestling. House crows and raven were the main egg eaters. The nestling losses were due to falling from the tree. The cat also predated nestlings on the nesting tree. Fledgling and nestling after falling from the tree were predated by dogs. Sand storms also destroyed nest. The adult Black ibis also fell down and wounded due to sand storm. Human disturbance also affected the breeding of the Black ibis nested on the neem tree as the leaves and sticks of this tree were cut and used as fire wood.

Nepotistic behaviour

Out of 14 nests studied in the study area during drought in 2006 only three were having one helper each. They were the young's of the previous brood of the breeding parents. These helpers were engaged in feeding the brooding female, nestling and fledgling, and defending the nest by vocalizing against the intruders. They were not found to help in nesting and incubation. The average clutch size, number of young hatched and young fledged were comparatively in the nest with one helpers. The nestling grew rapidly and all the chicks fledged earlier in the nest with helpers as compare to nest without helpers. None of the nests helped were predated.

Fig. 11: Young chick of the previous brood of Black Ibis helping the parents in breeding.

Fig. 12: Young Black ibis alarming to members by giving anti-predator vocalization.

You can download the full thesis here: The_Black_Ibis_Thesis.pdf