320 SHORT COMMUNICATIONS IBIS 121

REFERENCES ALLEN, J. 1973. STEPREG 1. Stepwise multiple regression analysis. Madison: University of

Wisconsin. CALDER, W. A. & KING, J. R. 1974. Thermal and caloric relations of birds. In Farner, D. S. &

King, J. R. (eds), Avian biology 4: 259413. New York: Academic Press. CROWE, T. M. 1978. The evolution of guineafowl (Galliformes, Phasianidae, Numidinae). I.

Taxonomy, phylogeny, speciation and biogeography. Ann. S. Afr. Mus. 76: 43-136. CROWE, T. M. & SNOW, D. ll'. 1978. Kumidinae. In Snow, D. W. (ed.), An atlas of speciation in

African non-passerine birds: 132-1 35. London: British Museum (Natural History). EHRLICH, P. & RAVEN, P. 1969. Differentiation of populations. Science, N.Y. 165: 1228-1232. ELGOOD, J. H., FRY, C. H. & DOWSETT, R. J. 1973. African migrants in Nigeria. Ibis 115: 1-45. JACKSON, S. P. 1961. Climatological atlas of Africa. Pretoria: Government Printer. JASfEs, F. C. 1970. Geographic size variation in birds and its relationship to climate. Ecology 51 :

JOHNSTON, R. F. 1972. Ecologic difierentiation in h'orth American birds. Univ. Arkansas Mus.

LCCAS, A. M. & STETTENHEIM, P. R. 1972. Avian anatomy integument. Part 11. Washington, D.C.:

~ ~ O R E A U , R. E. 1957. Variation in the western Zosteropidae (Aves). Bull. Br. Mus. (Nat. Hist.) 4:

NILES, D. M. 1973. Adaptive variation in body size and skeletal proportions of horned larks of

ROSENZWEIG, &I. L. 1968. Net primary productivity of terrestrial communities : prediction from

SOKAL, R. R. & ROHLF, F. J. 1969. Biometry. San Francisco: W. H. Freeman. THORNTHWAITE ASSOCIATES 1962. Average climatic water balance data of the continents. Lab. of

365-390.

Occ. Pap. 4 : 101-132.

U.S. Government Printing Office.

311-433.

southwestern United States. Evolution 27 : 405-426.

climatological data. Am. Nat. 102: 67-74.

Climatol., Publ. in Climatology 15: 114287.

FitzPatrick Institute University of Cape Town

Kondebosch 7700 South Africa

20 June 1978

T. M. CROWE

BREEDING BIOLOGY OF THE PARIAH KITE MIL VUS MZGRANS AT DELHI ZOOLOGICAL PARK

The Pariah Kite Milvus migrum is one of the commoner birds of prey in India. Several authors have given details of the nest, clutch size and measurements of eggs (Donald 1918, Ali 1926, Baker 1928, Dharamkumarsinghji 1954, Meyburg 1967, 1971) but, in spite of its abundance and importance, the species has not been thoroughly studied in India. Its density in Delhi is unusually high (Gallushin 1971). This paper treats data collected at the Delhi Zoological Park during 1973-1976. The Park is a woodland area of 240 acres (97 ha), in which Pariah Kites have nested in naturally occuring trees since its inception.

In all, 60 nestings occurred in the three years. The birds were watched through 8 x 30 prismatic binoculars. For the study of reproductive performance 15 occupied nests were followed each year. These nests were examined daily from December-April.

Eggs were marked with indelible ink for the determination of the incubation period, and weights and measurements of 102 were taken.

OBSERVATIONS

During the three successive seasons 1973-1974 to 1975-1976, some pairs laid eggs in November and December but the peak period was during January and February. Some nests with young were observed during December but in most nests the young hatched during February and March. Some nestlings left their nests in March, but most left during April-May and very few in June. 0019-1019/79/030320+06 $02.00/0 0 1979 The British Ornithologist's Union

1979 SHORT COMMUNICATIONS 321

During June-August, few Pariah Kites were present in the Park. During September numbers increased, to reach a maximum in December-March. It is likely that the birds moved into the Park to nest from adjoining neighbourhoods. The birds arrived already paired at the nesting ground. Soon after their arrival, construction of a new nest or repair of an old nest commenced. Nests were located at the bases and also at forks of the branches

TABLE 1

Dimensions and time required for construction of 15 nests in 1973-1975

Diameter Time Height of taken to nest from Length & of

started (days) level (m) (4 ( 4 (cm) Nest-building complete ground width depression Depth

26 Oct. 14 Nov. 21 Nov. 24 Nov. 25 Nov. 16 Dec. 18 Dec. 19 Dec. 19 Dec. 19 Dec. 19 Dec. 20 Dec. 20 Dec. 28 Dec. 31 Dec.

67 59 47 68 38 46 18 26 43 27 42 29 51 23 24

7.30 7.35 7.90 8.80 9.40 9.10 8.15 8.25 5.50

10.45 8.30 8.90 9.10 . _.

7.95 10.00

60 x 44 22.9 4 6 ~ 3 7 . 5 254 60x48.5 20.3 60x47.0 20.3 70 x 41 22.8

48.5 x 43.5 27.5 45 x 30 20.3

48.5 x 41 25.4 45 x 35 22.8 50 x 40 20.3 60 x 30 20.3

48.5 x 36 30.4 40 x 35 20.3 46x37.5 25.4 46 x 30 22.8

7.5 6.5 6.5 5.1 6.5 5.1 ~~

5.1 7.5 7.5 5.1 7.6 6.5 6.5 6.5 6.5

of Prosopis julij2ora, Ficus religosa, Eucalyptus sp. or Salmalia malbaricum, at heights of 7-10 m from the ground. Although a few sites were occupied by kites year after year, it could not be ascertained if the ownership remained the same, or changed. Those birds which occupied an old nest rearranged the twigs and added new material. Every season new nests were also constructed. Nest material consisted chiefly of 30-60 cm long dry twigs, picked by the birds from the ground, with the addition of iron wire, paper, rags, cotton, clods of soil, dry leaves, feathers, bones, etc.

In the initial stages of nest construction the sticks were arranged in a criss-cross fashion, to form an oval platform. As the sticks increased on the sides, a shallow depres- sion was formed in the centre. This depression was enlarged and later lined with thin,

TABLE 2

Time lapse between the completion of the nest and laying of the 1st egg, 1974-1976

Date nest 28 Dec. 29 Dec. 2 Jan. 7 Jan. 7 Jan. 14 Jan. 16 Jan. 16 Jan.

Days to first 10 7 5 12 13 7 14 13

Datenest 23 Jan. 3 1 Jan. 4 Feb. 13 Feb. 28 Feb. 2Mar. 23 Mar.

completed

egg

completed

Days to first 9 9 4 3 13 8 4 egg

322 SHORT COMMUNICATIONS IBIS 121

dry twigs, within which was placed an inner layer of cotton, rags or even mud. The nest-building continued after the eggs were laid. It was observed that sticks were collected b y both partners, but most by the female. Cumulatively they made 3-10 trips per day to bring sticks, and it took 18-68 days for a pair to complete the nest (Table 1).

Frequent copulations were observed during the nest-building period and even after the eggs were laid. Twenty copulations averaged 5-5 s (range 2-13 s) from stepping on to stepping off by the male. The eggs were laid 3-14 days after the completion of nests (Table 2). The successive eggs in a clutch were generally laid two or three days apart, but occasionally the interval was greater.

TABLE 3

Clutch size of Pariah Kite at Delhi Zoological Park

No. of eggs in a clutch

Season 1 2 3 hv. clutch size

13 6 2.0 3 1 3 2.5

1973-1974 2 19761975 3 1975-1976 1 8 9 2.4

Total 6 26 28 2.3

Kate: The freshly laid eggs were light green in colour, sometimes spotted with brown, and became dull and dirty coloured as incubation progressed. 102 eggs measured on average 53.9 mm in length (range 48.7-63.5 mm) and 42.6 mm (39.7-48.2 rnm) in width. The average weight of 102 eggs laid during the three seasons, recorded within 24 h of laying, was 49.8 g (range 39.7-78 g). The average weight of the eggs thus formed 6.6% of average body weight (756.5 g, n = 20 adults).

TABLE 4

Hatching success of 102 eggs of Pariah Kite in annual samples of 15 nests, 1973-1976

Hatching success Year Eggs laid Eggs hatched ( Y o )

1973-1974 33 19 1974-1975 37 20 1975-1976 32 17

57.6 54.1 53.1

Total 102 56 54.9

Of 60 clutches completed during the three years, 28 clutches (46.6%) were of three eggs, 26 (43.3%) of two eggs and 6 (10%) of only one egg (Table 3).

Incubation began soon after the laying of the first egg. Both sexes shared in incubation, but the female played the major part. The male usually remained nearby; he also brought food for the female. In ten nests, on average, the incubation contribution by the male amounted to 33.3% of observation time, by the female 61.8%, while 4.8% of the time the eggs were unattended. The incubation period was taken as the interval between the laying of an egg and its hatching. Thirty-six marked eggs successfully hatched. The position of these eggs in the laying sequence, and the size of the clutch of which they were part were not noted. Three of these eggs (8.3%) hatched after 29 days, 9 (24.9%)

1979 SHORT COMMUNICATIONS 323

after 30 days, 11 (30.5%) after 31 days, 3 (8.3%) after 32 days, 6 (16.6%) after 33 days, one (2.8%) after 34 days, and three eggs (8.3%) after 35 days, average 31.4 days. The interval between the pipping and final hatching of 28 chicks ranged from 1-3 days. Since most chicks hatched at intervals of at least one day, the nests rarely contained chicks of the same size, and the first chick was often five or more days older than the youngest. The hatching success of 102 eggs in sample nests was 55% (Table 4); 46 eggs failed to hatch due to infertility, predation, breakage, death of the embryo or other undetermined reasons.

TABLE 5 Fledging success in 15 sample nests each year, 1973-1976

Fledging Eggs Young success

Year hatched fledged ( Y o )

1973-1974 19 15 1974-1975 20 17 1975-1976 17 12

79 85 71

Total 56 44 78

Newly hatched chicks weighed on average 39.8 g (range 2 9 4 9 g, n = 25). They were guarded by both parents. The female played a major role in rearing the chicks and also went in search of food more frequently than her partner. The male generally sat on a nearby tree or in the nest tree.

The first attempt to feed the young was made when it was a day old. The female brought the meat in pieces in her beak and fed the chick by cutting it into still smaller pieces. Fish measuring 2-3 cm were also brought by the parents. The frequency of feeds dropped as the young developed. In a nest containing two chicks, the parents made 5-6 trips a day during the first 15 days, but only 2-3 trips per day when the chicks were 3 0 4 5 days old. Although the young were fed at any time during the day, food was commonly brought during the forenoon hours. The female was also observed to bring water for the young. The stronger (bigger) chicks fed first and, until satisfied, did not allow younger ones to approach the parents. On several occasions it was also observed

TABLE 6

Summary of causes of mortality among chicks in 15 nests each year, 1973-1976

Causes 1973-1974 1974-1975 1976-1977 Total (%)

Starvation - 1 - 1 (8.2) Predation 1 1 2 4 (33.2) Accidental

fall from nest, and unknown 2 2 3 7 (58.4)

Total 3 4 5 12

324 SHORT COhlMUNICATIONS IBIS 121

that the stronger chicks attacked the younger chicks, which became piogressively weaker and ultimately died of starvation. The dead chicks were eaten by the parents or thrown out of the nest.

During the three seasons, of 56 nestlings hatched in the annual sample of 15 nests, 12 did not survive to fledge, i.e., mortality 21.8% (Table 5). Mortality due to starvation was 8.2% during the first two weeks, since the parents were unable to meet the full require- ments of more than two chicks. Yet death due to accidental fall ( i t . , attributable to fighting among chicks, and also to high winds) accounted by far the greatest proportion of nestling mortality (Table 6). Once chicks reached the age of 3-4 weeks their prospects of further survival were much improved.

T A B L E 7

Dates ofjirstpight and finalpedging of 18 nestlings in 1974 and 1975

Duration of Duration of Date of final Interval after Clutch Date of first fledging leaving the 1st flight

Year size hatching flight period (days) nests (days)

1974 15 Jan. 6 hlar. 50 20 Mar. 14 2 16 Jan. 6 Mar. 49 20 Mar. 14 1 19 Jan. 6 Mar. 46 13 Mar. 7 3 25 Feb. 18 Apr. 52 10 May 22

25 Feb. 2 May 66 13 May 11 28 Feb. 2 May 63 13 May 11

2 28 Feb. 24 Apr. 55 29 Apr. 5 2 Mar. 24 Apr. 53 29 Apr. 5

1 2 Mar. 20 Apr. 49 8 May 18

1975 3 11 Feb. 1 Apr. 49

12 Feb. 2 Apr. 49 1 3 Feb. 2 Apr. 48

2 20 Feb. 7 Apr. 56 26 Feb. Died of starvation

2 3 Mar. 30 Apr. 58 3 Mar. 24 Apr. 52

1 15 Mar. 5 May 51 2 19 Mar. 12 May 54

21 Mar. 16 May 56

14 Apr. 1 3 17 Apr. 15 17 Apr. 15 28 Apr. 21

- - 19 May 14 18 May 6 19 May 5

TABLE 8

Repuoductiue succcss in 15 closely zcatched nests each season

No. of Reproductive Average number eggs No. of success of fledged young

Year laid young fledged (yo) reared per pair

1973-1974 3 3 15 45.4 1.0 1974-1975 37 17 35.9 1.1 1975-1976 32 12 37.5 0.8

Total 102 44 42.9 1 .o

1979 SHORT COMMUNICATIONS 325

The young began flapping their wings at the age of 30-35 days but they were actually unable to fly till they were about six weeks old. Even after they were capable of flying, the young continued to use their nests for several days, to roost at night and part of the day.

The average nestling period of 18 chicks during 1974-1975 from the day of hatching until they finally left the nest was 64.3 days (range 53-77 days) (Table 7). The combined incubation and fledging period averaged 85 days.

Overall reproductive success in the annual samples of 15 nests is summarized in Table 8. Mortality of nestlings ranged from 7*7-19-8y0 per annum (average of 12.8y0). Mortality among eggs was highest (42.2%) in 1975-1976 and lowest (36.5%) during 1973-1974 with an overall average of 30.2%. The combined mortality rate of eggs and nestlings was 51%.

REFERENCES ALI, S. 1926. Mating habits of common Pariah Kite (MiZous migrans gooindu). J. Bombay Natl.

BAKER, E. C. S. 1928. The fauna of British India including Burma and Ceylon, vol. 5. London:

DHARMAKUMARSINGHJI, R. S. 1954. Birds of Saurashtra. Bombay: Author. DONALD, C. H. 1918. The birds of prey of Punjab. J. Bombay Natl. Hist. SOC. 26: 826-835. GALLUSHIN, V. M. 1971. A huge urban population of birds of prey in Delhi, India. Ibis 113: 552. MEYEIURG, B. U. 1967. Observation of breeding biology of Black Kites (MiZvus migruns). Vogelwelt

MEYBURG, B. U. 1971. On the question of the incubation period of Black Kite (MiZww migrans).

Hist. Soc. 31: 524-526.

Taylor and Francis.

88: 70-84.

Ibis 113: 530.

Delhi Zoological Park,

10 February 1978 New Delhi-110003, India

J. H. DESAI A. K. MALHOTRA

DIET OF MEADOW PIPITS ANTHUS PRATENSZS ON MOUNTAIN GRASSLAND IN SNOWDONIA

The Meadow Pipit Anthus pratensis is one of the commonest bird species in upland Britain. In Snowdonia, a few birds are present during the winter but most of the breeding population migrates, returning from southern Europe in March.

During 1972 and 1974-75, in the course of a study of the ecology of the species on mountain grassland (See1 & Walton 1979), and under licence from the Nature Conservancy Council, I shot 304 Meadow Pipits. The birds were shot at weekly intervals from March- October, all between 11.00 and 13.00 hrs GMT, at two sampling areas, one on Moel Eilio in the Conway Valley and the other on Moel Siabod near Cape1 Curig. Both areas were sheepwalks above 300 m, dominated by NarduslMolinia grassland, often with Pteridium, Juncus and Calluna.

All birds were allocated to one of two age classes, i.e., Juvenile, a bird hatched in the current year, or Adult, a bird hatched in any year prior to the current year. Both classes were readily recognized by appearance both in the field and in the laboratory.

The stomach was removed from each bird, the contents washed out with 70% alcohol and examined. For each stomach a list of items was made. Only those remains which could be positively identified were recorded. For the most part, stomach contents con- sisted of arthropod material, ranging from undamaged specimens to fragments which gave no clue as to their origin. It seems likely that, as well as the soft parts, much of the chitin present in the exoskeleton of arthropods was eventually digested; Jeuniaux (1962) showed the presence of high chitinase activity in the gut of the House Sparrow Passer 0019-1019/79/030325+05 $02.OOjO 0 1979 The British Ornithologists' Union