The Foods of Kakapo on Stewart Island as Determined from ...BEST: FOODS OF KAKAPO 73 M odification...

H. A. BEST

Wildlife Service, Department of Internal Affairs, Private Bag, Wellington, New Zealand71

THE FOODS OF KAKAPO ON STEW ART ISLAND ASDETERMINED FROM THEIR FEEDING SIGNSummary: The diet and feeding methods of kakapo (Strigops habroptilus) on Stewart Island, southern NewZealand, were studied by examining sign left by the birds. Most feeding sign was found on herbs, ferns, andshrubs, especially on new and developing growth such as leaves, bark, fruits and seeds, as well as thesubterranean portions. The species on which most kakapo sign was found were Lycopodium ramulosum, L.fastigiatum, Schizaea fistulosa var. australis, Blechnum minus, B. procerum, Cyathodes juniperina,Dracophyllum longifolium, Olea ria wlensoi, Thelymitra venosa, Oreobolus strictus, Gahnia procera andCarex appressa. Though all (but Oreobolus and Gahnia) were fed on frequently throughout the year,variations in the use of different parts of plants occurred both seasonally and annually. The nature of thefeeding sign indicated that kakapo are versatile feeders with highly variable feeding patterns, and many foodsare taken opportunistically. This flexible feeding pattern allows kakapo to utilise a broad spectrum ofseasonal foods which may only be available for short periods or on intermittent years.

Keywords: Kakapo; Strigops habroptilus; Cacatuidae; food; feeding sign; feeding patterns; Stewart Island.

IntroductionThe kakapo (Strigops habroptilus, Gray 1845) isa flightless, ground-dwelling parrot endemic toNew Zealand. Presently, it is endangered,occurring only in Fiordland (where less than adozen birds are known; D. V. Merton, pers.comm.), on Little Barrier Island (onto which 22birds were released in 1982) and on StewartIsland, where it was rediscovered in January1977, and where studies to determine ways ofconserving the species are being conducted.Kakapo are difficult animals to study because

of their nocturnal habit, cryptic colouration and,except when males are present on their track andbowl systems in booming seasons (Merton 1975),their secretive behaviour. Without the use ofsuitably trained dogs they are virtuallyundetectable (Henry, 1903).This study of the foods and feeding habits of

kakapo was carried out on Stewart Islandbetween June 1977 and April 1980 on trips of3-8 weeks duration in summer, autumn, winterand spring, at a time when the use of dogs to findkakapo was not permitted. The only source ofinformation on kakapo foods was the feeding signand droppings left by the birds. *Some information on kakapo foods and feeding

habits on Stewart Island is contained in WildlifeService expedition reports (file WIL 25/4/19) andin brief published accounts (Russ, 1978; Best,1979). Gray (1977) reported on the feeding signof kakapo in Fiordland, on Maud Island (onwhich 9 birds were temporarily held) and on

* Subsequent to this investigation, dogs were used,kakapo captured and fitted with radio-transmitters andtheir movements monitored (Best, 1982).

Stewart Island. Further information is given byWilliams (1956), who reviewed the pre-1950sliterature, Reid (1969) and Merton (1975).

Study AreaThe study area lies at the south-east end of TinRange, Stewart Island (Fig. 1). From the indentedrocky shoreline the land rises steeply to 100 m in

Figure 1: Southern Stewart Island showing the locationof the study area and place names used in text.

New Zealand Journal of Ecology 7: 71-83 © New Zealand Ecological Society

72 NEW ZEALAND JOURNAL OF ECOLOGY, VOL. 7, 1984

altitude and then climbs gradually to the base ofTin Range 4 km inland. The hinterland ischaracterised by gently rolling hills dissected by amaze of irregular and intricate stream courses.Granite outcrops are scattered throughout thestudy area, but tend to be more concentrated atthe base of the eastern side of Tin Range. Thecrest of Tin Range rises abruptly to 500-600 m .a.s.1. and extends north-eastwards.

VegetationThe vegetation of the study area is a complex offorest, scrub, heath and moor land. Wind,altitude, watertable, fires and mining activitieshave influenced the vegetation structure andcomposition (Wilson, 1979). Seven broadvegetation types can be recognised (plant namesafter Wilson, 1982):(1) Coastal scrub - A narrow (< 50 m) belt ofwoody vegetation immediately adjacent to thecoast but penetrating further inland on exposedsites, such as headlands. The tight, umbrella-likecanopy is dominated by Olearia angustifolia andSenecio reinoldii.(2) Podocarp-hardwood forest - Moderatelyopen canopy up to 20 m high comprising mainlyrimu (Dacrydium cupressinum), miro (Podocarpusferrugineus), rata (Metrosideros umbellata) andkamahi (Weinmannia racemosa). Occurspredominantly within 300-500 m of the coast,but is found inland along the main river coursesand in pockets in sheltered places.(3) Manuka scrub - Established on burnt areasand encompassing a variety of sites ranging fromthose which manuka (Leptospermum scoparium)is just beginning to colonise, to dense pole stands6-7 m high. Areas dominated by manuka aremainly well-drained with variable understoreydensity, the understorey being least developedwhere manuka forms dense stands and a uniformclosed canopy. On these latter sites manuka formsa monoculture and the ground is carpeted in litterseveral centimetres deep. Understoreydevelopment increases as the canopy thins outand in some of the taller manuka stands die-backof poles has provided an open canopy underwhich podocarp-hardwood forest regenerationand/or dense groves of Gahnia procera sedgeoccur on favourable sites (e.g. drier areas onridges, knobs or hillocks, especially if facing northand sheltered from the wind).(4) Yellow silver pine scrub - Vegetation 1-3 mhigh, predominantly of yellow silver pine(Dacrydium intermedium) and manuka, with

leatherwood (Olearia colensoi), rata, rimu,kamahi, flax (Phormium cookianum) and Gahnia.On more sheltered sites, occasional emergents ofrimu or rata up to 8 m high are present. Thecanopy is mainly open to partly-closed, thoughdense thickets occur locally. This scrub is foundmost often on elevated exposed ground such assmall tablelands and broad, gently sloping ridgecrests below 300 m a.s.1.(5) Swampy flats - Typically clad in lowvegetation and scattered shrubs. The majorground cover comprises sparse to dense carpets ofjointed rush (Empodisma minus) and umbrellafern (Gleichenia dicarpa), though as ground coverdeclines, mosses and lichen become moreprevalent. Bare peat occurs intermittently, usuallymarking the location of ephemeral ponds andseepages. Flax is found mainly alongside waterbut some plants are scattered about on higherground. The sedge Carex appressa is distributedlocally adjacent to water courses and in someplaces completely covers shallow drains. Althoughstands of manuka are scattered over lower-lyingground, it becomes more prevalent as drainageImproves.(6) Subalpine scrub - 3-5 m high decreasing to1 m high at the altitudinal limit of the scrub'srange. Typically this vegetation type has a tight,wind-stunted canopy of leatherwood (dominantspecies), rata, Dracophyllum longifolium, yellowsilver pine, Hall's totara (Podocarpus hallii) andmanuka. Subalpine scrub is found mostcommonly on the flanks of the Tin Range above200 m a.s.l.(7) Alpine tops - Fell-field with wind-sculpturedshrubbery amongst the shelter of rocks; groundspringy underfoot, often waterlogged exceptaround rock or if the ground slopes appreciably.The turf comprises mosses, club moss(Lycopodium ramulosum), comb sedge(Oreobolus strictus) tussocks (Chionochloapungens, and other Chionochloa spp), mountaindaisy (Celmisia polyvena), Senecio bellidioidesand other herbs.

ClimateThe climate is maritime; mild to cool, highhumidity, cloudy with frequent rainy intervals. Itis often windy, predominantly from the NW, W,or SW. Although the ground and the vegetationmay be soaked frequently by showers, on exposedareas the moisture held in the foliage can beshaken free in a few hours and the ground surfacecan dry appreciably in a short time.

BEST: FOODS OF KAKAPO 73

Modification of vegetation by manThe study area is one of the more man-modifiedareas of Stewart Island. A major activity was tinmining, from the 1880s to 1940s (Howard, 1940;Sansom, 1982). Locally, adits were driven, atramline, surveyor's track and packhorse trackswere laid down and small sluicing and water-cannon operations were established to strip offthe peat mantle to expose alluvial deposits andgranite bedrock. Such activities, however, were ofminor consequence compared to the fires whichwere lit periodically to assist prospecting, andwhich have modified the vegetation over morethan 15 km2 of countryside between Tin Rangeand the catchments of Healys Creek andRobertson River (Fig. 1).

MethodsFeeding sign was found by walking slowlythrough an area, looking for evidence thatvegetation had been recently cropped, chewed,grubbed up or otherwise disturbed. If no sign wasapparent, specific attention was paid to the fernsSchizaea fistulosa var. australis, Blechnum minusand Blechnum procerum, the orchid Thelymitravenosa and the shrubs Olearia colensoi andDracophyllum longifolium, as these appeared tobe favoured plants, and often feeding sign onother species was associated with feeding sign onthese. Searches were concentrated along the edgesand under the canopy of low scrub, at vegetationtransition zones, around the margins and on topof granite outcrops, beside streams, and nearridge crests, flanks and faces of differing aspectthroughout the study area.

Identity of feeding signKakapo feeding sign can be confused with thatleft by deer (Odocoileus virginianus), possums(Trichosurus vulpecula), or rats (Rattus exulans,R. rattus and R. norvegicus). Confusion with deersign was probably rare and restricted mainly topodocarp-hardwood forest areas of RobertsonRiver and Healys Creek. Except for occasionaldeer in these areas, most were restricted to coastalforest.

Confusion with possum and rat sign wasprobably greater, for Gray (1977) noted that, attimes, possum and rat sign on some plants couldnot be distinguished from that made by kakapo.Possums and rats are widespread throughout thestudy area.

Because of possible confusion in identifying the

species responsible for leaving feeding sign,vegetation thought to have been taken by kakapowas examined very carefully. Grubbing, theformation of 'chews' (expectorated, crescent-shaped, masticated plant material; see Gray(1977) for details) and chewing of leaves ordefoliation of limbs too frail to bear the weight ofpossums were considered signs of kakapo feeding.Where distinctive kakapo sign was not evident,feeding sign on a plant was attributed to kakapoonly when (a) the material was adjacent todefinite kakapo sign or droppings, and (b) therewas absence of sign from other browsing animals.

Aging of feeding signAs little of the kakapo feeding sign was of knownage, estimates of age had to be made for assessingchanges of diet with season. Trials simulatingkakapo feeding sign were carried out on severalplant species in January 1979. The basal portionsof Astelia linearis (a herb), Schizaea (fern) andThelymitra (orchid) were dug up using a smallspoon. Olearia colensoi leaves were clipped, budsnipped and some new growth stripped down tothe bare sapwood. Some pinnae of Blechnum(fern) were clipped. Examination of this simulatedsign at regular intervals showed, unfortunately,that aging was neither well-defined nor consistent.

Grubbed up Astelia linearis appeared littledifferent after a day or a few weeks on the sitestested. Some Schizaea grubbings appeared 'old'within days, as litter had fallen into them, orspider webs had been set across the depressions;other grubbings appeared 'fresh' even after a weekor two. With Olearia and Blechnum it was notpossible to determine whether foliage had beencut one week or two weeks before. However,when the bark on Olearia twigs was stripped toexpose the new sapwood, the wood's pale greenshade and moist texture were retained for a fewdays but by the end of a week the tip of the newsapwood had darkened appreciably. GrubbedThelymitra orchids proved to be the bestindicators of the age of feeding sign because thesucculent, stalk-like leaves wilted after being cut.In exposed sites wilting was pronounced in a day,whereas in damper, sheltered sites it took severaldays.

Aging of sign was dependent on weather aswell as the microclimate of the site, especially itsexposure to sun and wind, and the moisturecontent of the air (for canopy material) or groundbeneath (for ground plants).

In the field only sign which appeared fresh was


recorded. This would include sign judgedconservatively to be less than a month old,though in many instances the material wasprobably only a day or two old.

ResultsA list of plants found eaten by kakapo on StewartIsland is given in Table 1. For each of the 25plant species involved, the parts eaten, thefrequency with which this was taken and theseasonal occurrence of feeding sign found aregiven. The list does not include plants or parts ofplants damaged by kakapo involved principally innon-feeding activities such as maintenance oftrack and bowl systems by male birds. Twenty-three of the food species were identified primarily

from feeding sign, and two, Cyathodes juniperinaseeds and Cyathodes empetrifolia leaves, fromexamination of droppings.

Feeding Sign1. Roots and rhizomesKakapo obtained the rhizomes of Lycopodium,Schizaea, Pteridium, Blechnum, and roots ofPhormium, Thelymitra, Carpha and Carex bygrubbing, a feeding method which created smallexcavations (1 x 2 - 4 x 4 cm) in the ground,often distributed patchily over an area of severalsquare metres. Grubbing for rhizomes ofLycopodium, which formed large mats, typicallycovered areas of 1-2 m2 but, in one instanceextended over an area of 25 m2.In very fresh grubbings bill impressions were

Table 1: List of kakapo foods on Stewart Island as determined by feeding sign.


clearly visible at the worked face of the excavatedarea (Fig. 2a, b). The rhizomes were brokencommonly into 1-2 cm lengths, which had beencrushed, presumably to squeeze out the starchycontents within. Other plant species weresometimes dug up during grubbing but did notappear to have been fed on and neither did theaerial portions of the food plants being grubbed.Balls of peat about 1 cm in diameter, scooped bythe bill, were often found in the grubbed area.Feeding on Schizaea rhizomes comprised biting

or slicing through the stipe at, or just belowground level leaving either a slight trace on theground, or scoops about 1 cm deep and 1 cmwide x 2 cm long. Sometimes a divot wasremoved in the process and placed to one side(Fig. 3a, b) with the stipes still intact, thoughmore commonly the aerial portions of the plantlay separately on the ground (Fig. 3c). The sign

Figure 2: A. Grubbing for Lycopodium rhizomes nearthe base of a Gahnia procera sedge. B. View of grubbedface. Note bill impressions in the peat wall (arrows) andthe broken sections of rhizomes and roots.

Figure 3: Feeding sign on Schizaea fistulosa. A.grubbing motion; B. divot of turf with intact Schizaea;C. felled Schizaea beside grubbing.


was not conspicuous but at times formed one ofthe main feeding signs in a locality.Grubbing was used also when kakapo fed on

Celmisia, Astelia and Oreobolus; this was not tofeed on the roots of these plants but to gainaccess to the apical areas of their leaves whichwere located at the bases of the plants.2. Material plucked from the ground or parentplantKakapo plucked material from the ground whenfeeding on Dicranoloma, Oreobolus, Centrolepis,Astelia and Celmisia, all of which form mats onthe ground. Sign on Dicranoloma moss was rareand consisted usually of a few tufts of foliagepulled out of the ground.

Oreobolus was fed on by a bird either pulling,wrenching or grubbing pieces out of the parentmaterial. Feeding sign was noted only on thebases of the plants just above the roots andformed a very small portion of the material pulledup. The discarded green portions were left intactand sometimes trailed a strand or two of rootmaterial (Fig. 4). Kakapo feeding sign onCentrolepis was similar to that on Oreobolus.When Celmisia and Astelia were eaten leaves

were pulled off individually and the baseschewed; a single lateral bite through the plant'score was used to remove the apical region at thebase of the leaf rosette, whilst the rest of theplant remained undisturbed in the ground; andthe innermost rosette of leaves was taken fromthe plant and the bases of the detached leaveschewed up.

Usually only one or two Celmisia or Asteliawere fed on at a site, but on one occasion, at an

Figure 4: Grubbed Oreobolus strictus portions onOreobolus and Dicranoloma turf.

area carpeted densely in Celmisia, plants along a40 m line of travel were torn up and strewnabout and chews were found amongst the leavesof undisturbed plants.

3. Basal stemsBasal stems were sliced through just above groundlevel. This feeding method was noted on the fernsCtenopteris, Pteridium and Blechnum and on theground orchid Thelymitra. In all cases the cutwas oblique and the opposing sides of the stemwere pinched in at the edge of the cut. When thismode of feeding was used on ferns, no other partsof the plants were taken - the aerial portionswere left on the ground untouched. ForThelymitra the entire leaf above the cut sectionwas taken and, in one example, 61 of 83 orchidplant leaves in an area of 50 x 100 cm weretrimmed.

4. Leaves, tillers and pinnae(a) Blechnum ferns. Feeding sign was found muchmore frequently on B. minus fronds than on B.procerum fronds. Usually, the pinnae wereclipped partly or entirely from the rachis(Fig. 5a). Alternatively, pieces were nibbled fromthe margins of a pinna (Fig. 5b, c) leavingscalloped markings, the edges of which wereslightly ragged (insect damage, in contrast, hadclean-cut, irregular edges, Fig. 5d).(b) Leaf tips of Halls totara, Dracophyllum,

flax, Juncus, Carpha, Gahnia, and Carex. Theleaf tips were chewed leaving the mangledconnective fibres on the plant for several weeks oreven months (Fig. 6).(c) Petioles, leaf bases and tiller bases.

Examination of fresh leaves found beneathOlearia shrubs revealed that 2-3 mm of thepetiole base had been nipped off, leaving short,protruding strands of connecting tissue(Fig. 7a, b, c). Kakapo probably held eachdetached leaf in one foot while feeding on thepetiole base. On one instance, 113 of 135 freshly-detached leaves found under one small shrub, hadhad their petiole bases removed.

The bases of detached leaves/tillers ofDracophyllum, Gahnia and Carex were chewedand discarded to litter the ground. On browsedGahnia and Carex tiller bases the juicy portionswere removed by mastication and the fibrousconnective tissue was left in a matted conditionstill attached to the remainder of the severedtiller. At times when feeding sign wasconcentrated on just a few plants, each had aflattened appearance indicating that the bird had


Figure 5: Feeding sign on Blechnumfronds. A. pinnaeclipped entirely (kakapo); B. pinnae nibbled either sideof the midribs (kakapo); C. close up of kakapo feedingsign on fern pinna. Note scalloped bite marks, raggededges to bites and zone of paler (dead) vegetationfringing the bites. A black area on the margin of theintact areas of the pinna is frequently associated withsuch feeding sign. D. insect feeding sign on Blechnumpinnae - clean edged, irregular patterned feedingdamage is characteristic.

Figure 6: Kakapo feeding sign on Dracophyllumlongifolium. The mid portions of leaves have beenchewed and the light green mangled connective fibreshave bleached to pale straw within a week.

been standing on the crown of the tussock-likeplants.(d) Leaf buds. Dracophyllum and Olearia leaf

buds were either eaten entirely, (Fig. 8) or a cleanbite was taken out of the side to obtain theinnermost new growth.(e) Entire leaves On Pseudopanax and Olearia

leaves feeding sign was most evident on newgrowth. In some instances a few bites had beentaken from the margins of the leaves, while atother times nearly all the leaf was eaten, leavingthe basal portion and the petiole attached to theplant (Fig. 9 a, b). Alternatively, on Olearia theyoungest leaf shoots in an opening leaf bud wereplucked out neatly, and a small tunnel in thefoliage rosettes was the only indication that


Figure 7: Petioles of Olearia colensoi. A. typical petiolebase when leaf pulled off tree; B. petiole base afterbeing fed on by kakapo; C. photograph of Oleariashrub showing branch tips where kakapo has beenfeeding on petiole bases (see arrows).

feeding had occurred. Chews were noticeable,especially when kakapo had been feeding recentlyon Olearia leaves (Fig. 9b); often many chewswere caught up in the tight canopy where the birdhad been feeding.5. BarkFeeding on bark was seen only on new growth ofOlearia twigs and most often the entire leafymaterial at the tip of the twig had been removedalso. Sign ranged from pieces of bark beingnibbled off in small patches through to all of thenew growth bark being stripped back to theprevious season's growth. Strands of bark wereleft hanging or were removed entirely (Fig. 10a).Sprouting of new buds was apparent on sometwig tips that had been stripped monthspreviously (Fig. 10b).6. Flower stalks and headsFlax flower stalks were fed on when the stalkswere fully grown but still succulent. On a fewplants a kakapo had mouthed the stems alongsections 5-25 cm above the ground, leavingnumerous crescent-shaped bill incisions in the skinof the stems, as if tasting the material. On otherplants, 10-30 cm sections at the stem base hadbeen removed leaving a hollowed stem coveredwith many bite marks. Within a few days thechewed stems had dried out.

Figure 8: Olearia colensoi - kakapo feeding sign onleaf bud. Black spot at tip of branch marks pitremaining after a bud has been removed. Adjacent leafbuds have not been disturbed.


Figure 9: Olearia colensoi - kakapo feeding sign onleaves A. photograph of leaf cluster from which someleaves have been fed on (see arrows); B. photograph ofa section of canopy that kakapo has fed on. Arrowsmark eaten leaves (L), 'chews' (C), and denuded branchtips (D).

Evidence of kakapo feeding on flax seed headswas as follows. Ripe seed heads were found onthe ground, still attached to their stalks witheither pieces bitten out of them, or covered indistinctive bill imprints where a bird hadmanipulated them. As with the flower stalks, theseed heads had been fed on when they had turnedblack but had not dried out. The bird must haveclimbed each 1-1.2 m high stalk to cut the seedheads down.7. SeedsThe presence of neat piles of clipped lengths ofGahnia seed heads, arranged with the stems inparallel rows, was considered to be evidence ofkakapo feeding. The stems had been cut cleanlyand obliquely. and the seedless husks wereundisturbed (this could be duplicated only by

Figure 10: Olearia colensoi - A. drawing of branch tipstripped by kakapo. All the foliage and some of thenew growth bark has been removed (cf with virtuallyintact leaf cluster at end of branch in Figure 8); B.photograph of new growth foliage sprouting at end of adenuded branch tip.


pinching the seeds at their point of attachment).The arrangement of cut material indicated that abird had stood in one place while snipping offseed heads. Probably each cut length of seed headwas held by a foot until the seeds were removed,after which the stem was dropped.

Sign which was attributed to rats feeding onGahnia seed heads differed from that describedabove in that the edges of cut sections of stemswere ragged, the seed husks were sometimesgnawed through, the majority of seeds on a cutstem had not been removed, and the stems werenot piled in parallel rows beside the parentGahnia.

Gahnia seeds were found in droppings ofkakapo, as also were seeds of Cyathodesjuniperina.

Seasonal variation in dietKakapo diet, as revealed from feeding sign,changed seasonally. The data on seasonal use offoods on Table 1 are a composite of several year'sobservation. For any particular season variationsoccurred in the relative abundance of feedingsign; for example, in 1978 feeding sign onDracophyllum longifolium leaves was found to becommon only in winter and spring, but in 1979this sign was found readily throughout the year.

The plants taken most frequently throughoutthe year were Lycopodium ramulosum, L.fastigiatum, Schizaea fistulosa, Blechnum minus,B. procerum, Cyathodes juniperina,Dracophyllum longifolium, Olearia colensoi andThelymitra venosa. Feeding on Lycopodium andBlechnum rhizomes, Thelymitra roots and bulbsand Olearia petioles was more common in lateautumn-early spring than in the warmer monthsof the year, while feeding on pinnae of Blechnum,the leaf buds of Dracophyllum, the leaf buds, newleaves and new bark of Olearia and leaves ofThelymitra was more apparent in spring-summer-autumn. Generally, in spring and summerthrough into autumn feeding sign tended to beconcentrated mainly on new growth anddeveloping foliage while from late autumn toearly spring most feeding sign was onsubterranean parts of plants. Cyathodesjuniperina fruits were present all year and seedswere found in kakapo droppings at any time ofthe year.

At certain times of year parts of other foodspecies were taken frequently. These were theleaves of Cyathodes empetrifolia (summer),Gahnia procera (autumn-winter-spring) -

especially in autumn 1979 and Carex appressa(autumn-winter), and in some years the seeds ofGahnia (late summer-autumn) and Phormiumcookianum (late summer-early autumn), roots ofPhormium (late summer-early autumn) and flowerstalks of Phormium (mid summer).

Phormium cookianum produces flowers andseeds in summer, but irregularly and duringflowering-seeding years feeding sign on theseitems was concentrated locally.

General feeding patternThe distribution of feeding sign suggested that themain feeding pattern was one of discontinuouslight browsing, such as would result if a birdwere sampling foods whilst on the move. Oftenone piece of feeding sign led to another a fewmetres further on, with no one particular speciesbeing favoured. Individual plants of the samespecies were often treated differently, e.g. onOlearia shrubs there may have been intensivefeeding on the leaf tips at one place, the petiolebases at another, and emergent leaves further on.In some cases, for example when feeding onCarex, some individual plants were clipped almostto ground level while adjacent plants wereundisturbed. On occasions, birds appeared tohave gone to considerable trouble to feed onindividual Carex plants, clambering over some tofeed heavily on others.

From time to time kakapo left conspicuousevidence of their feeding activities. On theseoccasions areas from 10 x 10 m up to50 x 100 m were fed on heavily, a variety offoods taken and numerous droppings left (over 30droppings at two such areas). Sign ofconcentrated feeding activity occurred mostly inmanuka and yellow silver pine scrub.

The methods used by kakapo to obtain foodwere a mixture of the neat and the untidy.Nipping of Olearia and Dracophyllum leaf budswas clean and precise, whereas extensive grubbingfor Lycopodium rhizomes appeared to have beendone energetically, leaving a mangled heap ofplant remains. The two contrasting methods wereused when feeding on the same species e.g.,Celmisia leaves were typically plucked one by oneor the plant core cut through neatly, yet at timesentire plants were uprooted.

Though kakapo may spend much of their timeon the ground it is evident that they haveconsiderable climbing skills (see also Henry,1903; Gray, 1977). On many occasions I foundfeeding sign at the branch tips of shrubs,


especially on Dracophyllum longifolium andOlearia colensoi.While some of the lowerbranches may have been accessible from theground, in most cases birds would have had toclimb the shrubs to reach the shoots and leavesconcerned.

Distribution of feeding signNo kakapo sign was seen in coastal scrub orpodocarp-hardwood forest within about 200 m ofthe sea in the coastal parts of the study areavisited (principally Healys Creek and Maori Creekcatchments but with occasional sorties along theold Culler's track). Inland, kakapo feeding signwas distributed widely through to the crest of TinRange, including the western flank of the rangenorthward to at least McArthurs Creek.Most of the kakapo sign found in the study

area was in yellow silver pine scrub and man uk ascrub, with very little sign being noted in inlandpodocarp-hardwood forest, swampy flats (excepton Carex) and subalpine scrub or on the alpinetops. Kakapo feeding sign was not distributedevenly in manuka scrub and yellow pine scrub.Sign tended to be most common on drier,elevated sites such as hillocks, ridges, tablelands,mounds, outcrops and knobs. On such sites theopen-canopy, woody vegetation, from 1-5 mhigh, sometimes graded through to moredispersed cover with shrubbery dotted about. Thecanopy gaps allowed the penetration of light andheat to the ground while the woody vegetationdissipated the wind.The ground storey was open, comprising

typically a mosaic of lichens, mosses,Lycopodium, Schizaea, Pteridium, Thelymitra,Astelia, Cyathodes empetrifolia, Carpha,Oreobolus and scattered litter, with flax,Dracophyllum, five-finger, Gahnia, Cyathodesjuniperina, and Olearia as understorey plants.The herb species fed on by kakapo and thefeeding sign on them declined markedly as close-set ground vegetation (e.g. dense groves ofGahnia, carpets of jointed rush and umbrellafern, or where podocarp-hardwood regenerationformed low thickets) occupied progressivelygreater areas. Such close-set ground vegetationtended to choke out many of the kakapo'spreferred food species, stayed damp (especiallyduring the winter) and may have been moredifficult for kakapo to move through. Likewise,very little sign of kakapo was found in closed-canopy, pole stands of manuka as dense litter

covered the ground, and there was a lack ofunderstorey or ground plants for birds to browse.

Discussion

Kakapo diet on Stewart Island: comparison withother studiesGenerally, the foods of kakapo on Stewart Islandreported in this account are similar to thosedescribed by Gray (1977) for Fiordland, MaudIsland and Mt Bruce Native Bird Reserve. That is,feeding sign was found most often on herbs, fernsand shrubs, though fruits and seeds from treeswere taken when in season. The parts of plantsmost sought after were either subterranean ornew growth such as leaves, bark and fruits-seeds.These parts of the food plants probably containedthe highest nutrient levels.Some of the kakapo foods on Stewart Island

identified in my study were of the same species (9of 25 species) or genera (17 of 21) listed by Gray(1977) (Table 1). Plants reported to have been fedon only from Stewart Island are Lycopodium,Schizaea, Ctenopteris, Centrolepis, Thelymitra,Oreobolus, Dacrydium, Podocarpus. Thoughthese species are all present in Fiordland, not allmay have occurred in the particular kakapo areasstudied by Gray (1977). Of the above StewartIsland foods, Schizaea, Centrolepis, andOreobolus seem to be strange choices becauseonly minor portions of these small plants aretaken and the energy gain per plant fed on wouldnot seem to be great.Other differences in feeding were apparent

between studies and areas. Kamahi stems andpetioles were reported by Gray (1977) to be oneof the four favourite foods of captive birds at MtBruce Native Bird Reserve, but no feeding sign onthis plant was noted in Fiordland (Gray 1977)nor on Stewart Island. Gaultheria antipoda fruitswere common in one or two droppings from onevalley in Fiordland but not from other valleys(Gray, 1977); on Stewart Island no record ofkakapo taking this plant was obtained in mystudy.

Validity of feeding sign for diet assessmentThe use of feeding sign produced a bias whenassessing the diet of kakapo as conspicuous formsof sign were more likely to be found than lessconspicuous ones. In some cases feeding bykakapo on certain berries and fruits and on thefoliage of small leaved plants could only be


confirmed by identification of fragments in thedroppings. Sign of feeding on such items was verydifficult to detect on the plants concerned andeven then may not have been attributable solelyto kakapo.Likewise a bias may have occurred when

determining the vegetation types kakapo preferredto feed in. Discovery of most of the feeding signin manuka scrub and yellow silver pine scrub mayhave arisen because sign was more obvious inthese two habitats than elsewhere. In manukascrub and yellow silver pine scrub the majority ofthe plants eaten were less than 2 m high and thuswithin close range of human vision. The groundwas generally not concealed from view anddroppings were relatively easy to find.By contrast plants in podocarp-hardwood forest

were distributed over a vertical range of 15-20 mand feeding sign above human eye level was notlikely to be seen unless exhaustive searches weremade using binoculars. Also, the understoreyplants in the forest tended to be less concentratedthan in manuka scrub or in yellow silver pinescrub and thus, feeding sign on these plantswould be more dispersed. Thirdly, it was moredifficult to find droppings in podocarp-hardwoodforest, as any that fell more than a metre or tWodisintegrated on hitting the ground or may havebeen hidden in groves of Blechrum discolor whichcovered large areas of the forest floor.Subalpine scrub was the most difficult of the

vegetation types to search because of the close-set,tangled nature of the trees, the uneveness of theground, the deep moss, prostrate trunks andoutcrops of rock. As Olearia colensoi andDracophyllum longifolium (which are frequentlytaken by kakapo) are dominant species insubalpine scrub, the birds probably use thishabitat more often than indicated from theamount of sign I found.

The level of kakapo sign found on the alpinetops indicated that birds fed infrequently in thisvegetation type. However, I suspect that, as withsubalpine scrub, kakapo fed on the alpine topsmore often as this vegetation type contained arange of food species similar to that taken bykakapo in Fiordland (Gray, 1977), especiallyadjacent to the subalpine scrub, and in the moresheltered places.

The paucity of feeding sign and droppingsfound on swampy flats (except in the vicinity ofCarex appressa) probably reflected a genuine lowuse of this habitat for feeding by kakapo.Swampy flats were easy to search for feeding sign

and the majority of feeding sign and droppingswas seen on the better drained fringes of swampyflats (where the main food species became moreplentiful) rather than centrally.

Conclusions on kakapo habits based on theirfeeding signThe habits of kakapo inferred from myobservations of their feeding sign agreed withthose of Gray (1977) for Fiordland and MaudIsland in that:1. the preponderance of sparse feeding sign overlarge areas suggested that birds were solitaryand ranged widely at night.

2. The variety of plant species eaten, the parts ofplants taken, and the methods used to obtaintheir foods, showed that kakapo were versatilefeeders.

3. Feeding patterns were variable, and ofteninconsistent, even in areas of similar habitat atthe same time, suggesting that individual birdsmight have had their own preferences. Thisinconsistency of feeding pattern was even morenoticeable when short-lived foods of sporadicoccurrence (e.g. flax flower stalks) for thefoods concerned may be gorged upon in onlyone or two small areas and left untouchedelsewhere.

4. Feeding sign tended to be more concentratedon ridge crests and well-drained, sunny slopes,for at these places the variety of plant life wasgreater generally and more concentrated thanon surrounding sites.

5. Kakapo are nocturnal feeders, but they mayalso feed or move about in the daytime.

6. The birds are skilled climbers and can scalevertical trees and limbs quite readily, and moveinto the crowns and outermost branches oftrees at least 15 m high.

7. The type of feeding sign left, and thus thefeeding technique used by the birds on StewartIsland, is similar to that in Fiordland.

8. Of a plant species fed on in a small area it wasoften found that, while some specimens werecropped heavily, others were browsed lightlyor undisturbed.

Final commentsBecause of the difficulty of finding sign that wasattributable solely to kakapo, the list of foods inTable 1 is likely to represent only a fraction ofthose taken by the birds on Stewart Island. Use ofdogs and radio-telemetry subsequent to this studyhas given a large data base on the locations and


feeding ranges of individual kakapo and thussearches for feeding sign can be directed to wherebirds have been.

Another factor limiting the list of kakapo foodson Stewart Island was that my study was for arelatively short term. A much better picture of theresponse of kakapo to the spectrum of foodsavailable to them would arise from a study of 10years or more. This is because some foods, suchas the flowers, fruit and seeds of podocarps,hardwoods and tussocks have irregular cycles ofabundance. A 10-year study would have a betterchance of covering the sequence of 'boom andbust' for these plants. Although kakapo may feedvery little on such plants for intervals of two orthree years, they may be of major significance tothe birds during times of high production. Onekakapo activity likely to be prompted by a suddenproduction of high energy food is breeding, forkakapo do not nest every year, and as only thefemale tends to the young (Best, 1982) she mustfind plentiful supplies of foods for four-fivemonths within walking distance of the nest forherself and her young.

freely on radio schedules and backup suppott.Constructive comments on earlier drafts of the

manuscript were made by Drs M. C. Crawley,J. A. Mills and R. G. Powlesland, andM. J. Williams, for which I am most grateful.

ReferencesBest, H. A. 1979. Kakapo on Stewart Island. Wildlife

- a review 10: 16-24.Best, H. A. 1982. (unpublished). An appraisal of

kakapo research and management. Wildlife ServiceReport. 45pp Mimeo.

Gray, R. S. 1977. (unpublished). The kakapo (Strigopshabroptilus, Gray 1845), its food, feeding andhabitat in Fiordland and Maud Island. M.Sc.thesis, Massey University, Palmerston North.

Henry, R. 1903. The habits of flightless birds of NewZealand: with notes on other flightless NewZealand birds. Government Printer, Wellington.

Howard, B. H. 1940. Rakiura; a history of StewartIsland, New Zealand. Reed, Dunedin.

Merton, D. V. 1975. Kakapo. Wildlife - a review 6:39-52.

Reid, B. E. 1969. Kakapo. Wildlife - a review 1:6-15.

Russ, R. B. 1978. Stewart Island kakapo. Wildlife - areview 9: 37-42.

Sansom, Olga. 1982. In the grip of an island: earlyStewart Island history. Craigs, Invercargill.

Williams, G. R. 1956. The kakapo (Strigopshabroptilus Gray) - a review and reappraisal of anear extinct species. Notornis 7: 29-56.

Wilson, H. D. 1979. Botanical survey of StewartIsland. In: Purey-Cust, J. R.; McClymont, R. B.(Editors). Stewart Island Land Management Study1978. pp 223-36. New Zealand Forest Serviceand Department of Lands and Survey, Wellington.

Wilson, H. D. 1982. Field guide to Stewart Islandplants. Field Guide Publications, Christchurch.

AcknowledgementsThe following people assisted me in the field andprovided cheer during the numerous periods whenthere was little sign of kakapo to be found for theeffott put in; W. Cash, A. Cox, P. Jamieson,P. Jansen, E. Kennedy, A. Mardon, R. Russ,P. Thomson (all of Wildlife Service), J. Anderson(Lands and Survey), A. Wiltshire (Forest Service)~B. Campbell and D. Mules. Thanks also are givento the Lobb family for their many hours given

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