Food and feeding behaviour of the great Indian bustard Ardeotis nigriceps (Vigors)

14 Pages·1992·8.3 MB·

by  Bharat Bhushan

:
FOOD AND FEEDING BEHAVIOUR OF THE GREAT INDIAN BUSTARD
ARDEOTIS NIGRICEPS (VIGORS) 1
BharatBhushan2 andAsad R. Rahmani3
(With twoplates andfourtext-figures)
Introduction hyaPradesh.Theaverageannualrainfallrecorded
by us from 1983 to 1985was 966 mm. Summers
ThegreatIndianbustardArdeotisnigriceps (MarchtoJune)areveryhot(maximumrecorded
,
endemictoparts oftheIndiansubcontinent, is an 48°C),buttemperaturesas lowas 4° Chavebeen
endangered avian species. It is included in recorded inwinter(Novemberto February). The
ScheduleIoftheWildlife(Protection)Act, 1972, terrainis gentlyundulating, withscatteredstones
andanumberofsanctuarieshavebeenestablished andboulders.
for its protection (Rahmani 1987, 1989). The Theoriginalvegetationoftheareawasclas-
present study on the food and feeding behaviour sified as Tropical Dry Deciduous Forest (Cham-
ofthespecies forms part ofa widerinvestigation pion and Seth 1968). There are a few hillocks,
on its ecology. Studies on food and feeding be- which some decades ago would have been
haviour were mainly done at Karera Bustard coveredwithAnogeissuspendulatrees,butindis-
Sanctuary, Madhya Pradesh, butwhereverneces- criminate cutting and lopping have eroded the
sary, data from othersites such as Nanaj bustard hills, leavingstunted specimens. The plains have
area in Solapur district, Maharashtra, and Rol- degradedintoopenscrub.Whereverpossible,the
lapadu Bustard Sanctuary in Kumool district, land has been cultivated. Today the shrubs
Andhra Pradesh, are also included. ZizyphusrotundifoliaandAcacialeucophloeaare
Owingtoitsstatusasagamebird,thenatural the dominant natural plants, the latter scattered
history ofthe great Indian bustard, including its and the former in clumps in all the uncultivated
food, has been described by many workers; but parts oftheplains.
thereisnodetailedstudyonits feedingbehaviour In the scrub area, along with Zizyphus,
andseasonaldependenceondifferent fooditems. variousgrasseswerefoundbutseverelyexploited
This paperdeals withthese aspects. The study is by livestock. Except forprivate fields, the entire
based largely on faecal analysis. While previous area was totally grazed. Among grasses
reviews of food habits analyses (Hartley 1948, Heteropogon contortus, Cynodon dactylon,
Van Tyne and Berger 1959, Korschgen 1969, Andropogonpumilus, Pennisetum pedicellatum,
Lorin 1970) maintainthat analysis offaecal mat- Aristida spp. andEragrostrisspp.werecommon.
A
ter should be the last alternative for study, they number of ephemeral streams run across
also accept that it is the only solution where the sanctuary and flow into the village tanks or
endangeredspecies are concerned. rivers. These streams dry up by the end of Sep-
tember or October. With constant soil erosion in
StudyArea
the hills, the dried streambeds showpresence of
The202.21sq.kmKareraBustardSanctuary soil, gravel and rocks all alongtheir course.
(25°30’ to 24°40’N, 78°5’ to 78°12’ E) (hence- Thereare33villageswithintheboundary of
forthKarera)is located inShivpuridistrict, Mad- the Sanctuary, and both human density (127per-
sons/sq. km) and the livestock population
1AcceptedFebruary1991.
2,3BombayNaturalHistorySociety,HombillHouse,Shaheed (179.5/sq. km) are high.
BhagatSinghRoad,Bombay400023. The bustards are found in open scrubland.
3Present address Centre for Wildlife and Ornithology, During our study period, there were about 25
AligarhMuslimUniversity,Aligarh202001. bustardsintheSanctuary.Thebreedingseason at
JOURNAL,BOMBAYNATURAL HIST. SOCIETY, Vol89
Fig. 1.StudyareaintheGreat IndianBustardSanctuary,Karera.
J. Bombaynat. Hist. Soc.89 Plate 1
Bhushanand Rahmani: Great Indianbustard
GhanaCicerarietinumplantmatterrecoveredfrombustardfaeces.Left:wholeshreddedandfibrouspodmaterial.
Rightabove:wholeseeds.Rightbelow:shreddedandfibrousstalkmaterial.
Mantidcacoons(right) afterrecoveryfromfaecal matter,ascomparedtotheirshapebeforebeingeaten(left).
9
J. Bombaynat. Hist. Soc. 89 Plate 2
Bhushan andRahmani: GreatIndianbustard
^
•
• * w
*)•*««*«
4c
* • «
f
i
tMI
1
A"'
-
ill
Coleopteranbodypartsrecoveredfromfaecal matter.
Orthopteranbodypartsrecoveredfrom faecal matter.
FOOD AND FEEDING BEHAVIOUR OF THE GREATINDIANBUSTARD 29
Karera is frommidMarchto endJune.Although the bird was watched continuously for a five
occasionalnestswerefoundinJulyandAugustas minute unit, termed here as a ‘scan'. During a
well, courtship display of adult males was not single scan, eachpeckby the bustard away from
seenafterJune. itslateralpositionwascounted.Thetotalnumber
The other areas were Nanaj (for details see ofpecksinasingle scanwasconsideredtobethe
Ali and Rahmani 1982-84, Rahmani and feedingrate(orpeckrate) forthatparticularscan
Manakadan 1989) and Rollapadu (see (afterMcKee 1982). The scancountwas discon-
ManakadanandRahmani 1989). tinuedwhenthebird went outofview.
Peck rates were studied from May 1982 to
Methods
August 1984 and 1271 readings were taken,
Study plots: Seven plots where bustards spread over different seasons and months. For
were seen foraging were selected (Fig. 1). The various reasons, equal numberofreadings could
names of these plots are based on local names. not be taken every month orevery season. Most
Detailed descriptions of the plots are given by readings were taken during the breeding season
Bhushan(1985) andRahmani (1989). (summer) and in winter, when the birds were
Analysis offaecalsamples: Morethan300 watched more regularly.
faecal samples were collected at Karera for Identification: To study the peck rate of
analysis to determine the bustard's varying de- different individuals, bustards were identified as
pendence on seasonal food. Most ofthe samples (i) Alpha male = adult territorial male; (ii) Beta
were collected from roosting sites. Wet samples male=subadultnon-territorialmale;(iii)Juvenile
werepreservedin 10% formalin,anddrysamples male=lessthanoneyearold,generallyseenwith
preserved in separate packets for later analysis. themother; (iv)Mother= henwith juvenile; (v)
Analysis was done on the basis of Korschgen Breeding female = hen with an egg or a chick;
(1969) and Lorin (1970). Faecal material was and (vi) Non-breeding female = hen without an
studied under a stereoscopic binocular micro- egg orchick.
scope.Variousitemsinthedietwereidentifiedby Entomological studies: Sweeping method
comparisonwithreferencematerial ordirectly in was used to count the insect number. Weekly
the case of such undigested parts as chelicera sweeps were carried out in different plots. 100
(arachnida) elytra and mandible (insects), seed sweeps eachwere done overa fixed stretchofan
,
(Triticum,Zizyphus andpod (Cicer,Arachis). areaineachplot,between0700and0900hrs.The
)
Figs. 2and 3showthepercentageweightof mainemphasiswas onthestudyofgrasshoppers,
various fooditemsinthefaecalmaterialcollected which constitute the major animal food of the
fortnightly. Although insects appear to be bustard, and are comparatively large and easy to
preferred by the bustards (visual observations), identify and count. Moreover, sweeping method
they are under-represented inthe figures, mainly is muchmoreeffectivetostudythepopulationof
becausetheyweredigestedandthusdidnotshow OrthopteraandLepidopterathanColeoptera.The
relativeproportions inthe faecalmaterial. Onthe insects caught or flushed during sweeping were
other hand, plant material is over-represented counted.
mainly because many plant parts (i.e. seed) The following were the common Orthop-
remain undigested and are thus easily identified terans andLepidopterans foundinthestudyarea:
andweighed.Smallreptileswhichareopportunis- Acrida exaltata, Chloeobora sp., Chrotogonus
tically eaten (visual observations) were not spp., Dnopherula sp., Gastrimargus africanus
,
recorded inthe faecal material. Theselimitations Locusta migratoria, Pyrgomorpha sp.,
shouldbekeptinmindwhileinterpretingfigures. Spathosternumsp.fAcoryphaspp.,Catantopssp.,
Feedingrates: Thebustards were observed Chorthippus sp., Eyprepoenemis sp.,
while foraging by the scanning method, wherein Hieroglyphus sp., Patanga sp., Poicilorhynchus
3
30 JOURNAL,BOMBAYNATURAL HIST SOCIETY, Vol89
Insect V/l Zizyphus Eruca l\\l Cicer
U
Other crop* Miscell. Unident. PlantLL Pebbles
1 I
'Arachls/Trltlcum/Sesamum
1983
100
75 - =
50 -
25 - ± == ==
Fig.2.PercentageofvariousfooditemsinfaecalsamplesofgreatIndianbustardcollectedin 1983.
Insect V/l Zizyphus 144-1 Eruca N\1 Cicer
Other crops* Miscell. Unident. PlantDZD Pebbles
1 1 I 1
1984
lOOnnnnfflPP
Fig.3.Percentageofvariousfooditemsinfaecal samplesofgreatIndianbustardcollectedin 1984.
FOOD AND FEEDING BEHAVIOUR OF THE GREAT INDIANBUSTARD 31
No. of Orthopterans
Fig.4.Monthwiseandinter-annualvariationinnumbersofOrthopterainthestudyarea.
pictusandSphingonotus sp.; and Tarucus indiea, forest plantation, dominated by various grasses
I nara I theoplirastus,Eurema brigitta Precis (height >100 cm) and some trees (density >1
, ,
lemonias Precis orithyia Papilio demoleus tree/10ha), (v)Outsideplantation:verysimilarto
, , ,
Acraea violae Hypolimnas misippus and Open scrub, i.e. dominated by Zizyphus rotun-
,
Belenoismesentina. difolia', this category wasselectedtocomparethe
ThoughColeopterans arecommonlyeatenby countswiththe adjoining Plantationplot.
bustards(AliandRipley1969,Bhushan1985),they
Results
are mainly crepuscularornocturnal, and are rarely
caught in the sweep net. Pitfall traps (using petri- Population fluctuationofOrthopteraand
dishes filledwithformalintotrapbeetles)werenot Lepidoptera: AtKarera,theorthopteranpopula-
used in order to avoid accidental drinking of for- tion was very low during winter (October to
malin by bustards and wild mammals. Moreover, February).FromthemiddleofMarch,itstartsrising
there were always chances of petri-dishes being and reaches its peak during the late summer or
brokenbygrazinglivestockorby blackbuck. monsoon. Inter-annual variation was seen in
Five habitat types were selected for insect population as well as in the timing of peaks and
studies: (i) Open scrub; dominated by Zizyphus troughs(Fig.4).Thesewerealsodependentonlocal
rotundifolia (averageheight 50cm)andvery low factorssuchasprecipitationandtemperature.
tree density (<1 tree/10 ha), (ii) Usar area; bare, The lepidopteran number, on the other
alkaline area, dominatedbyChlorisstricta grass. hand, is generally low in late winter and sum-
(iii)Wooded scrub: dominated byZ. rotundifolia mer, butsoonafterthemonsoonbreaks, itstarts
andAcacia leucophloea (tree density > 5/10 ha). increasing and reaches its peak during August
(iv) Inside plantation; totally protected 20 ha and September.
32 JOURNAL, BOMBAY NATURAL HIST. SOCIETY, Vol.89
Table1
LITERATUREREVIEWOFTHEFOODOFTHEGREATINDIANBUSTARD
Foodrecorded References
Insects
''Grasshoppers,Mylabris,Buprestris Scarabaei..." HumeandMarshall 1879
,
"Grylli,beetlesofallkinds(Cetonidae,Elateridae, Elliot1880
Buprestidae,Carabidae),frequentlythespongynidus
ofthemantis,caterpillars,Julidae,Scolopendridae...."
"Locusts,grasshoppers,beetles,crickets,mole-crickets,ants" Dharmakumarsinhji 1957
GreenblisterbeetleCantharistenuicollis AliandRipley 1969
Beetles{Gymnopleurusl Atactogaster Gupta 1975
, )
Curculionidae:Platynotus,Mylabris Stemoceranitidicollis Manakadan1985
,
Scorpions,spidersetc.
"Centipedes,spiders,scorpions,worms" HumeandMarshall 1879,Elliot1880,
Dharmakumarsinhji 1957,Gupta 1975
Reptiles
"Lizards,snakes..." HumeandMarshall 1879,Dharmakumarsinhji 1957,
AliandRipley 1969
Echiscarinatus Carter 1912
Uromastixhardwiddi Gupta 1975
Birdeggs
EggofCotumix HumeandMarshall 1879
Mammals
Rats HumeandMarshall 1879
Mice Dharmakumarsinhji 1957
Plants*
"greenshootsoflemongrassCitronella" Dharmakumarsinhji 1957
Carissa HumeandMarshall 1879,Gupta 1975
Salvadora Dharmakumarsinhji 1957
Inanimatematter
"stones&gravel","pebbles" HumeandMarshall 1879,Elliot1880,
Dharmakumarsinhji 1957
"brassornament" HumeandMarshall 1879
PlantsincludedherearenotlistedinTable2.
FoodRecordedThroughFaecalAnalysis weight) in the first fortnight ofOctober 1983, in
SeasonalVariation thesecond fortnightthey declinedto 7% (Fig. 2).
On the other hand, the percentage of Zizyphus
Winter(Octoberto February): Winterin increased from65to 68%.
Karera starts in October; Insect numbers start In November also, drupes of Zizyphus
declining, and the monsoon crop such as constitute the major food (Fig. 2). Soeha
groundnutArachis hypogea as well as Zizyphus Eruca sativa which is a dryland winter
, ,
drupes, start ripening. In the beginning of Oc- crop at Karera, is relished by bustards. So
tober, bustards were mainly seen feeding on in- is groundnut; bustards are frequently seen
sectsanddrupesofZizyphus.Bymid-October,the in groundnut fields, foraging on exposed
insect numberdeclines rapidly andbustards feed nuts. They do not dig up the plants. How-
more and more on the ripe drupes of Zizyphus. ever, we did not obtain groundnut in faecal
While insects constituted 13% of the diet (by samples.
FOOD AND FEEDING BEHAVIOUR OF THE GREATINDIANBUSTARD 33
Table2
PLANTSPECIESIDENTIFIEDINTHEBUSTARDDIET
Family Species Remarks
CRUCIFERAE Erucasativa Crop
Brassicacampestris Crop
MALVACEAE Hibiscusabelmoschus Wildplant/weed
TTLIACEAE Triumfettarhomboides Wildplant
LEMACEAE Linumusitatissimum Crop
RHAMNACEAE Zizyphusrotundifolia Wildplant
LEGUMINOSAE Cicerarietinum Crop
Arachishypogea Crop
Vignasinensis Crop
CUCURBITACEAE Cucumismelo Wildplant/weed
PEDALIACEAE Sesamumindicum Crop
GRAMINEAE Sorghumvulgare Crop
Triticumvulgare Crop
InDecember,thepercentageofZizyphus in 3). This could be due to a sampling error. In 1983
thedietofbustardsdeclinedtolessthan50%(Fig. only five samples were analysed in each fortnight
2), while the percentage ofEruca sativa did not while in 1984, 12 and 16 samples were studied,
change significantly. Similarly, there was not which showed the diet variation more clearly. In
much change in the insect constituents. Vegetal February, as in other winter months, insects
matter remained the major part of the diet as formed lessthan 10% ofthe dietofthe bustard (as
indicated bythe faecalsamples. shown by faecal sample analysis).
AlthoughZizyphusdrupes aremore orless Summer(March to June): Inearly March,
exhausted by January, bustards were still able to the Bengal gramand soeha start ripeningbutthe
pickupsufficientnumberstoconstituteupto51% bustards are still seen in the crop fields, picking
byweightinthefirstfortnightof1984(Fig.3).In up the late flowers of soeha and unripe pods of
both 1983 and 1984, in the second fortnight of Bengal gram. Insects start increasing in number
Januarythepercentage ofErucasativa increased (Fig.4)butstillformedlessthan10%inthefaecal
(Figs. 2, 3). samples analysedbyus (Figs. 2, 3).
This is further corroborated by our visual BythethirdweekofMarch,whenharvesting
observations inthe field. The insect numberwas ofearly-grownwheatbegins,bustardscanbeseen
very low (Fig. 4) and hence bustards were more in newly harvested wheat fields, picking up the
frequently seen in the crop fields of soeha and fallengrains.Soehaisalsoharvestedbythefourth
Bengal gram Cicer arietinum Sometimes com- week of March, after which bustards are rarely
.
plete pods ofgram were found in the droppings seen in soeha fields. Breeding of bustards at
butwe rarely sawthemeatingthepods ofsoeha. KarerastartsfromthemiddleofMarch(Rahmani
Occasionally, theywereseenfeedingonmustard 1989). During the first fortnight ofApril Bengal
BrassicacampestrisandtilSesamum indieum. gramis the mainstanding crop eatenby bustards
InthefirstfortnightofFebruary,Erucasativa at Karera, and constituted nearly 50% ofthediet.
constituted 14.7 and 23.4% in 1983 and 1984 Its percentage declined during the second
respectively, while in the second fortnight it in- fortnight(Figs.2,3).Atthesametimethepercent-
creasedto33.6and45.7%(Figs.2,3).Similarly,the ageofwheatincreased in faecalsamples as more
percentage of Bengal gram also increased in the fieldsareharvested.BythethirdweekofAprilall
second fortnight. In 1983, we found very little wheatfieldsareharvestedandlivestockgrazedon
Zizyphusinthefaecalsamples,unlike1984whenin crop residue.
boththe fortnights,Zizyphusconstituted28% (Fig.
34 JOURNAL BOMBAY NATURAL HIST. SOCIETY, Vol. 89
,
With the approach of summer and rise in whichisaddedtothefoodofthebustardfromthis
temperature, small reptiles come out ofhiberna- month onward till it is harvested in Novem-
tion and the population of Sitana ponticeriana ber/early December. Bustards are firstseeninthe
,
Agama minor Mabuya spp., Ophisops jerdonii groundnut fields whenit is sown, and laterwhen
,
and Calotes versicolor increases. Sitana, it is ready forharvesting. As the groundnutplant
Ophisops andAgama are easily caught by forag- isveryshort(20-30cm),it issuitableforbustards
ingbustardsbecausethesesmalllizardsgenerally and the birds are regularly seenthere.
depend on camouflage, remaining immobile BytheendofSeptember, monsooncropsare
when danger threatens. We often saw bustards harvestedandfieldsareprepared forwintercrops
withsmall lizards, but rarely saw themcatching suchaswheat,soehaandBengalgram.Theinsect
Calotes versicolor which is mainly arboreal. An numbersstartdeclining.Atthesametime,drupes
injured Calotes offered to our captive-cum-free ofZizyphus start ripening and more bustards are
ranging juvenile bustard at Rollapadu was not seen picking the drupes from bushes. The cycle
eaten by it (Manakadan and Rahmani 1990). repeats itself.
However, we suspect that an adult bustard can
CropPlantsEatenbyBustards
easily eat a Calotes because we have seen them
eating snakes, sometimes larger than an adult Soeha: Soeha or taramira is a dry-land
Calotes. wintercrop extensively grown in Karera and the
DuringMay andJunethereishardly any crop wholeofnorth-westIndia. Wehaveseenitgrown
at Karera and bustards depend totally on natural inSorsan,Sonkhaliya(Rajasthan),Ghatigaonand
food (Figs. 2, 3). Insects, especially Orthopterans, Pohri (Madhya Pradesh) bustard areas/
reachmaximumnumbers, and formthe mainfood, sanctuaries. The whole plant - inflorescence,
though this is not reflected in faecal analysis for leaves and shoots -is eaten by bustards. As long
reasonsstatedearlier(Fig. 4). as there are flowers and fresh green leaves, bus-
Monsoon (July to September): With the tards areseeninsoeha fields. Someofthehighest
onset of the monsoon in end June or early July, peck rates were found in the soeha fields (see
agricultural activities begin and millet, pen- Table 3).
nisetum, sesamum and groundnut are grown. In- Soeha is a marginal crop, grown only in
sect numbers remain high and constitute nearly those areas where irrigation facilities are scanty.
10% of the diet of the bustard (as indicated by Ifa field canbe irrigated, farmers preferto grow
faecalsamples,thoughitmustbehigher)(Fig. 2). more commercially profitable crops.
In August 1984 (we have no data for August Bengal gram: After soeha, Bengal gram
1983), insects constituted 47.31% in the first Cicer arietinum is the most preferred crop of
fortnightand 18.52% inthesecond fortnight(Fig. bustards at Karera. Cool dry climate and light
3). well-drained soil are essential forsuccessful cul-
Bustards also feed on Cucumis melo var. tivation. It can be grown with or without irriga-
momordicum. Locally known as ‘gila’, the tion. The plant is 30-40 cm tall and is grown in
cucumber-like Cucumis melo is locally con- narrow rows. At Karera, it is mainly grown in
sidered as a weed and grows naturally in non-irrigatedormarginallyirrigatedareas.Some-
groundnut fields. Bustards feed on the fruit (3-5 times it is grownwithwheat.
cm long and 2-3 cm broad), and presumably Bustards eat young shoots, flowers and un-
digest the entire fleshy matter and possibly the ripe pods ofBengal gram. The highestpeck rates
unripe seeds also, because only the hard seeds were observed inBengal gram fields (Table 3). If
were found in faecalsamples. undisturbed, they visit the same gram fields over
DuringSeptember, insects constituted about consecutive days. We have recorded stems,
20% ofthe diet (Fig. 3). Groundnutis anewcrop leaves, seeds and pods in the faecal samples.