Grit Use in the Sarus Crane Grus Antigone

2005·2.2 MB·

by  K S Gopi Sundar

MISCELLANEOUS NOTES
Table 1: Thedietand its preference bythe Nicobar significant variation in precipitation (Kruskal Wallis test,
Megapode H=7.81, df=2, p=0.02).The datareportedhereagreedwith
other reports for the genus Megapodius: that they are
Fooditem Rankbasedon Rankbasedon
omnivorous(Jones etal. 1995).
Volumetric frequency
proportion of occurrence This study is funded by the Ministry ofEnvironment
andForests, GovernmentofIndiaandthelogistic supportby
Macarangapeltata 1 1 the Forest Department, Andaman and Nicobar Islands, has
Dictyoptera (cockroaches) 2 2 been invaluable in the execution of this study. We thank
Snails 2 3
V.S.Vijayan,LalithaVijayan,ReneDekker,DarylJones,Yash
Litters 3 2
Beetles 4 4 VeerBhatnagar,JuguluMehtoandPremRamfortheirvaluable
Ants 4 4 inputs in this study.
Unidentified 4 3
Grasshopper 4 5 December12,2002 K. SIVAKUMAR1
Pauropodans 5 5 SANKARAN
R.
Hermitcrab 5 5
Reptilescale 6 6 SalimAliCentreforOrnithology
andNatural History,
Like other megapodes, the Nicobar Megapode also Anaikatty,Coimbatore640108,
forages by scratching and raking the debris on the ground. TamilNadu, India
More precipitation reduced the foraging activities of the 'PresentAddress: Wildlife Institute ofIndia,
=
Nicobar Megapode (Spearman correlation test: r -0.46, P.O. Box. 18,Chandrabani,
p= 0.05). Foraging patterns varied significantly between the DehraDun24800 Uttaranchal, India.
1,
years (Kruskal Wallis test: H= 9.23, df= 2, p<0.01), due to E-mail:[email protected]
REFERENCES
Ali, S. & S.D. Ripley (1983): Handbook ofthe Birds of India and ofAustralian birds. Emu 12: 8-18.
Pakistan. Compact edition. Oxford University Press, Bombay. Coles,C.(1937): SomeobservationsonthehabitsoftheBrushTurkey
737 pp. (Alecturalathami).ProceedingsoftheZoologicalSocietyofLondon
Altmann, J. (1974): Observational study of behaviour: sampling 107(A): 261-73.
methods. Behaviour 48: 227-265. Gill,H.B.(1970): BirdsofInnisfailandhinterland.Emu 70: 105-116.
Booth, D. T. (1986): Crop and gizzard contents oftwo Mallee fowl. Hess,H.C.(1997):Stomachflushing:samplingthedietofRed-cockaded
Emu 86: 51-53. Woodpecker. Wilson. Bull. 109(3): 535-539.
Brookes,G.B. (1919): Reportoninvestigationsinregardtothespread Jones,D.N.,R.W.R.J.Dekker&C.S.Roselaar(1995):TheMegapodes.
ofprickly pear by the Scrub Turkey. QueenslandAgricultural Oxford University Press. 262 pp.
Journal II: 26-28. Kennedy, M & P. Fitzmaurize(1972): Someaspects ofthebiologyof
Cleland,J.B. (1912): Examination ofcontentsofstomachs andcrops gudgeonGobiogobio(L.)inIrishwaters.J. Fish. Biol 4:425-440.
11. GRIT USE IN THE SARUS CRANE GRUSANTIGONE
Introduction K.S.Gopi Sundar pers. obs.), no information exists on
Grit is generally ingested by granivorous and the amount and kind of grit ingested by Sarus Cranes. In
herbivorous birds, and to a smaller extent by insectivorous this paper, we present information on grit use by the Sarus
birds (Weltry and Baptista 1988). The main purpose ofgrit Crane in India based on contents of three Sarus Crane
intakebybirds isto facilitatethe mechanicalgrindingin the gizzards.
gizzard ofany hard, coarse material ingested by the bird.
However, gritmayalso providecalciumto femalebirdsjust METHODS
beforethe breedingperiod(Harper 1964). Grit use patterns
arefairlywellunderstoodforGalliformes(Dalke 1937;Sadler The gizzards ofthree SarusCranes(one eachofasub-
1961) and for ‘cornfield birds’ (Best and Gionfriddo 1991; adult, male and female bird), whichhad been collected after
GionfriddoandBest 1996). Whileseveralobservationshave theirdeath dueto suspected pesticide poisoning(S. Sharma,
beenmadetowardsingestionofgritparticlesbySarusCranes pers. comm.), were obtainedfromKeoladeo GhanaNational
(J. Langenberg pers. comm., M. Nagendran pers. comm.. ParkinBharatpur,India.Theageofthesebirdswereunknown
106 J. Bombay Nat. Hist. Soc., 102 (1), Jan-Apr 2005
MISCELLANEOUS NOTES
and could only be inferred from the development ofthe red a
colouration onthehead(Ali and Ripley 1980). The gizzards
werefoundtocontain largeamountsofvegetablematterand
grit. The gizzards were sliced open, all the contents were
flushed onto petri dishes, and the grit separated, washed and
dried.
Characterization ofgrit was done following Best and
Gionffiddo(1991).Threemeasurementsusedtocharacterize
the grit were: 1) Size - the average of the longest and the
shortest dimensions of each particle was calculated by
measuring the two dimensions with Vernier callipers to the
nearest0.01 mm.2)Shape-gritshapeindexwascalculatedby
dividingthelongestdimensionwiththeshortest.Theparticles
representing a spherical shape would have an index of 1.0 Size classes (mm)
and grit with values greaterthan unity were deemed oval to
oblong, and 3) Roundness - gritroundness was measured by b
classifying all particles in five categories, namely Angular,
Sub-angular, Sub-rounded, Rounded and Well-rounded.
Roundness index was calculated by giving grit particles a
value of 1 forAngular, 2 for Sub-angular and so on; values
tendingtowardsfivewouldmeangritwithcompletelysmooth
surfaces.
mm
Grit particles with the longest dimension <1 were
excluded from the analysis, assuming that they were
accidentally ingested by the cranes, or were broken down
fromlargerparticles. Veryfewparticles(<1%)wereexcluded
fromthetotalsampleforthisreason.All gritparticlesofeach
bird wereweighedtogethertothe nearest0.0 gm.
1
RESULTS Shape index classes
c
Atotalof523 gritparticleswerecountedandmeasured
fromthegizzardsofthethreeSarusCranes.Thetotalweight,
number ofgrit particles, mean grit size and mean grit shape
areindicatedinTable 1.Thoughthemalebirdhadthehighest
mean grit size, the two largest grit particles (> 10 mm) were
found in the other two birds. The largest range ofgrit sizes
was seen inthe sub-adultand female bird(Fig. la). Most grit
mm
particles(80.7%)inallthreegizzardswerebetween2-6 in
size (Fig. lb). While the sub-adult and the female bird had
mostgritparticles in the size range of2-4 mm, the male bird
had mostgritparticles inthe4-6 mmrange(Fig. la). Mostof
theparticles(69%)hadashapeindexof1.5-2.5 (Fig. 1b). The
malebirdhadthe largestvarietyofshapes(9 classes)andthe Roundness categories
female, the least(6 classes). All three birds used most ofthe
gritparticles inthe shape index range of1.5-2 (Fig. lb). The Fig. 1: a. Percentcompositionofgritparticlesacrossdifferentsize
mostrepresentedgritroundnesscategorieswereSub-angular classes;
and Sub-rounded (77.6% ofall particles, Fig. lc). The least b. Percent composition of grit particles across different
shapeindexclasses;
represented roundness category was Well-rounded (n=l) in
c. Percent composition of grit particles across different
theentiresample.The largestproportionofAngularparticles roundnesscategories
J. Bombay Nat. Hist. Soc., 102 (1), Jan-Apr 2005 107
,
MISCELLANEOUS NOTES
Table 1: Characteristicsofgritin Sarus Cranes (Table 1). Mostofthegritparticlesusedbythemalebirdwere
alsoofahighersize classcomparedtothose intheothertwo
Gizzards Numberof Total Mean Shape Mean birds(4-6mmasagainst2-4mm). Largersamplesizeswill be
sampled grit weight size index Roundness required to adequately explore gender and age related
particles (gm) (mm)
differences in grit use patterns in Sarus Cranes.
Sub-adult 108 13.46 3.92 2.01 245 From this study, itappearsthat Sarus Cranes generally
mm
(1.1-10.41) (1.18-4.55) use grit particles between 2-6 in size and opt for grit
Adultmale 220 35.95 4.5 2.2 2.94 particles with intermediate degrees of roughness and
(1.28-8 57) (1.11-5.62) roundness. Intheory, angularparticleswithsharpedgeshave
Adultfemale 195 22.65 3.68 1.94 2.74 the greatest efficiency in digesting coarse food substances,
(1.03-11.8) (1.17-3.89) but also pose the risk ofdamaging internal digestive organs.
Rangeofmeansizeandshapeindexofgritisgiveninparentheses In contrast, well-rounded particles have the lowest risk with
respecttophysical injury,butwillbe leastefficientinbreaking
was seen in the sub-adult bird. All three birds used most of down food. In this respect, Sarus Cranes seem to be using
thegritparticlesintheSub-roundedcategory(Fig. lc). Mean gritparticlestomaximizedigestionwhileavoidingexcessive
roundness ofgrit particles was almost the same in all three physical damage to digestive organs. This data set is useful
birds(Table 1). in that it provides information to aviculturists and zoo
managersonthekindofgritthatshouldbeprovidedtocaptive
DISCUSSION Sarus Cranes.
While use ofgrit in birds is known to differwith body ACKNOWLEDGEMENTS
size, gender, reproductive status and availability, diet is
knowntobethemost importantfactorinfluencinguseofgrit WethankMrs. ShrutiSharma,Director,KeoladeoGhana
(Gionfriddo and Best 1996). Increase in number of grit National Park for providingthe Sarus samples forthe study.
particles isusually in bird species with adiet ofhard, coarse A. Tamim helped with the transport ofthe samples and S.P.
material,particularlyseedsandvegetablematter(Gionfriddo Rajkumarassisted in the autopsy, storage ofgizzards, and in
and Best 1996), and in species with a varied, unspecialized sexingthe birds. Wethankthe Director, Wildlife Institute of
diet. The Sarus Crane (Grits antigone) in India is known to Indiaforfacilitiesand infrastructureprovidedundertheSarus
beomnivorous, itsdiet includinggrainofseveral kind,plant CraneProject. M.S. Rana(Wildlife InstituteofIndia), andB.
shoots, tubers of aquatic plants, frogs, lizards and other Didrickson(InternationalCraneFoundation)providedlibrary
reptiles, grasshoppers and other insects, vegetable matter, support. KSGS thanks J. Langenberg, D. Mudappa, M.
fruits, molluscs (Hume and Marshall 1879, Baker 1929, Nagendran, T.R.S. Raman and M. Spalding for discussions
Ghorpade 1975), fish (Law 1930) and occasionally eggs of and comments on a previous draft.
other birds (Sundar 2000). The omnivorous habit of the
species most likely facilitates the intake of such large December30,2002 K.S.GOPI SUNDAR1
quantities ofgrit. Many ofthe foods reported for the Sarus B.C. CHOUDHURY
are calcium-rich, and it is unlikely that grit is ingested to WildlifeInstituteofIndia,
supplement calcium, but primarily fulfils a mechanical P.O. Box 18,Chandrabani,
function. DehraDun248001, Uttaranchal, India.
Sarus Crane males are larger than females, and sub-
adultsareconsiderablysmallerthanadultbirds(AliandRipley 'PresentAddress: C/o Wildlife SocietyofIndia,
1980).Thismayexplainthedifferenceinthehighernumberof M-52,GreaterKailashPart-1
grit particles and the correspondingweight ofthe gizzard of NewDelhi 110048,India
the male bird, andthe smallervalues forthe othertwo birds Email: [email protected]
Ali, S. & S.D. Ripley (1980): Handbook ofthe Birds of India and wadersandothersemi-sportingbirds. PartVII.J. BombayNat.
Pakistan. Vol 2: Megapodesto Crab Plover. OxfordUniversity Hist. Soc. 33: 4.
Press, Delhi. Best, L.B. & J.P. Gionfriddo (1991): Characterization ofgrit use by
Baker,E.C.S.(1929):ThegamebirdsoftheIndianEmpireVol.V.The cornfieldbirds. WilsonBull. 795:68-82.
108 J. Bombay Nat. Hist. Soc., 102 (1), Jan-Apr 2005
MISCELLANEOUS NOTES
Dalke, P.L. (1937): Food habitsofadultpheasants in Michiganbased Harper, J.A. (1964): Calcium in grit consumed by hen pheasants in
on crop analysis method. Ecology 18: 199-213. east-central Illinois. J. Wild/. Manage. 28: 264-270.
Ghorpade,A.M. (1975):Noteson thefeedingoftheSarusCraneGrus Law, S.C. (1930): Fish eating habit of the Sarus Crane (Antigone
antigone antigone (Linnaeus). J Bombay Nat. Hist Soc. 72: antigone). J. BombayNat. Hist. Soc. 34: 582-583.
199-200. Sadler, K. (1961): Gritselectivity by the female pheasant duringegg
Gionfriddo, J.P. & L.B. Best (1996): Grit-use patterns in North production.J Wildl. Manage. 25: 339-341.
American birds: the influence ofdiet, body size, and gender. Sundar, K.S.G (2000): Eggs in the diet ofthe Sarus Crane (Grits
Wilson Bull. 108: 685-696. antigone). J. Bombay Nat. Hist. Soc. 97: 428-429.
Hume, A.O. & C.H.T. Marshall (1879): The Game Birds of India, Weltry,J.C.& L. Baptista(1988):TheLifeofBirds.SaundersCollege
Burma & Ceylon. Vol III. John Bale, London. Pp. 4-5. Publishers,N.Y.
12. OBSERVATIONS OF MATE CHANGE AND OTHER ASPECTS OF PAIR-BOND IN
THE SARUS CRANE GRUS ANTIGONE
Sarus Cranes Grus antigone are known to be and the frequency of duet calls (which is also used for
monogamous and pair bond is thought to last throughout the advertisement during territorial defence, Archibald 1976)
livesofthebirds(AliandRipley 1989).Themaleandfemaleof increased. Inmid-August,thepairconstructedanestofTypha
apairare known to strengthen the pair bond by synchronized reeds in the marshland and the female laid two eggs, both of
behaviours such as duet calls, dance, guard-calls and alarm- which were removed byvillagers.
calls(Masatomi 1994;Archibald 1976).Theactualdurationof OnSeptember8,2000,duringaroutinevisittothearea,
pair bond, prevalence ofmate change and factors leadingto another bird was seen in the territory and repeated attempts
such changes are unknown in Sarus Cranes. In this note, I by the resident pair to chase the visitor (duet calls, tertial-
report the first evidence of divorce or separation in Sarus elevation strutsandco-ordinatedguardcalls)failedtoelicita
Cranes with observations on other aspects ofpair bond and response. In a surprising move, the visitor attacked the
territoriality. residentfemale(identifiedbysmallersizeandpostureduring
Overtwohundred and fiftybreeding,territorialpairsof duet calls). At first, the male assumed threat postures and
Sarus Cranes were monitored between December 1999-July carried out displacement preens, tertial-elevation struts, and
2002 as part ofa study on their biology and conservation in a directed walk threat at the visitor. These attempts failed to
the districts ofEtawah and Mainpuri in Uttar Pradesh. The displace the visitor, which instead renewed attacks on the
study area has the highest known density ofterritorial pairs residentfemale. Thevisitorwassmallerthantheresidentmale,
and number ofSarus Cranes anywhere in the world. Pairs/ but largerthan the resident female. The resident female and
familieswererecognizedbycolour-bandingthejuvenileseach thevisitorsparredforalmostfiveminutes,peckingeach other
year, with individual physical marks on adult birds, or by and indulging in rapid, violent bouts ofjump-rakes. The
location. Pairs, particularlythosewith young, wereobserved residentfemalewasclearly losingthebattle;the largersizeof
one to seven times a week (average offour observations) to the visitor could have proved to be an advantage. At this
collect data on breeding success, feeding habits, territory point, the resident male, which was otherwise circling the
size, and activitybudgets. Mate change was observed in two fighting pair of cranes, walked in and pecked the resident
instances and is discussed in this note. “Divorce” or change female. The resident female began running away from the
ofpairmembership was actually observed in one pair, while visitor,givingalarm-calls, andthemaleresponded bycalling
mate change could be deduced in another. In addition, other synchronously, but did not come to the rescue. The visitor
relevant aspects of pair bonding, territoriality, and related became very aggressive and mounted a fresh attack on the
behaviours observed are described and discussed. The resident female by kicking, jump-raking, wing-thrashing,
behaviour terminology used throughout the text follows sittingonthe backofthe bird and peckingthe neck and head
Ellisetal. (1998). hard and rapidly, finally chasing the bird into a pond and
forcing it to swim to the opposite bank. The male was now
Matechangeobservation 1 chasing the resident female as well, and clearly supporting
Theterritory ofone pairwas very close to the town of the visitor, though he synchronouslyanswered thealarm and
Etawah, and consisted ofa large Typha-bordered marshland guard-callsofthe resident female.
and crop fields. The pair had successfully raised one chick On emerging from the lake, the resident female was
during the breeding season in 1999-2000, and was seen to pursued once again by the visitor. This time, the female
defend the territory from other Sarus pairs and groups deliberately, but cautiously, approached human observers
throughouttheobservation period. In earlyAugust, the adult standing on the side ofthe marshland and stood as close as
birdswereobservedtochasethesub-adultfromtheterritory, 5 m. Thisdissuadedthevisitorfromattackingfurtherand she
J. Bombay Nat. Hist. Soc., 102 (1), Jan-Apr 2005 109