48 McNEIL: MAN, DEER AND VEGETATION IN MICHIGAN

New Zealand has a similar history of log- REFERENCES ging, followed by the plough or fire, or similar disturbances. In addition, since all the BAIRD, ''Y., 1954. This is our Michigan. Federated ungulates have been introduced in a short Publications, Battle Creek, Mich. time, biologically speaking, the native plants BALD, F. C., 1954. Michigan in four centuries. Harper are generally ill-adapted to maintain them- Bros., N.Y. selves under heavy browsing pressure. An JENKINS, D. M., 1961. Michigan's deer industry. Mich. inevitable imbalance between animal numbers Cons. 30: 17-21. and the amount of available food has resulted. The eventual status of deer in New Zealand JENKINS, D. R., and BAHTLETT,1. H., 1959. Michigan may be much the same as in Michigan: (1) whitetails, Game Div., Dept. Cons., Lansing. browsing pressure by ungulates will continue MICHIGAN DEPARTMENT OF CONSERVATION, 1960. strong for some time, resulting in changes in Twentieth biennial report, 1959-1960. Mich. Dept. species composition of various plant communi- Cons., Lansing. ties; (2) continued control measures will PERRY, O. H., 1899. Hunting expeditions of Oliver reduce deer numbers and inevitably an altered Hazard Perry of Cleveland, verbatim from his flora and fauna will evolve (some native diaries. Marion Press, Jamaica, N.Y. species probably becoming rare or extinct); RYEL, L. A., and FAY, L. D., 1962. Deer biological data (3) eventually a balance between plant and 1961-62. Report No. 2387. Game Div., Mich. Dept. animal numbers (probably artificially de- Cons. pressed by shooting) will occur; (4) political VERME, L. J., 1962. Mortality of white-tailed deer fawns and social problems will continue to play an in relation to nutrition. In Proc. 1st Nat. White- important role in natural resource manage- tailed Deer Diseasf! Symposium, Univ. of Georgia, ment. Athens, Georgia: 17-28,37-38.

DISPERSAL AND DESTRUCTION OF SEED IN CENTRAL NORTH ISLAND PODOCARP FORESTS

A. E. BEVERIDGE Forest Research Institute, Rotorua

INTRODUCTION Seed dispersal and destruction have been Over the past six years studies have been studied by observing the feeding habits of birds carried out, mainly in dense podocarp stands and by examining seed and droppings on the of Pureora and Pouakani Forests, to gather ground, on collection sheets, and in seed traps, information about the periodicity, abundance, some of the latter being rodent and bird proof. and soundness of seed crops, the animals that Seed has also been fed to captive rats and disperse or destroy seed, and how they do so. insects. Recently the populations of rodents The ultimate objective is to find out what part in different forest types have been studied by each bird, rodent or insect plays in assisting systematic trapping with break-back traps or limiting regeneration of timber species. baited with peanut butter. In January 1962, at Pureora, P. C. Bull of the Animal Ecology Division, D.S.I.R., demon- METHODS strated that mist nets can be used in native Seed crops were assessed subjectively until forest to capture birds so that their role as seed 1961, when pairs of seed traps were placed dispersers can be studied. beneath crowns of permanent seed trees of rinlu (Vacrydium cupressinum), totara (Podocarpus RESULTS totara), kahikatea (Podocarpus dacrydioides), SEED CROPS AS A FOOD SUPPLY mira (Podocarpus jerrugineus) and matai Podocarps (Podocarpus spicatus). Since 1961, the num- There is a marked periodicity in fruiting ber of sound and defective seeds collected in amongst some podocarp species but no regular the traps has been counted annually. interval between good seed crops has been BEVERIDGE: DISPERSAL AND DISPOSAL OF PODOCARP SEED 49

observed (f.linds and Reid iM;;\. In any year, n1pen)ng oj seed crops one or several species may fruit well in a par- At Pureora Forest, the earliest ripe fruit is ticular locality, or there may be few sound found in December on second-growth species seed of any species in the forest interior. In such as fivefinger and fuchsia. Wineberry and Pureora Forest, seed-crop ratings have been the first tawa berries ripen in February. Ripe recorded as follows for the past 10 years: rimu seed with fleshy receptacles is available rimu: good crops in 1954 and 1958; fair crop in 1962; from mid March to May when the bulk of the kahikatea: good crops in 1955, 1960 and 1963; fair kahikatea, miro and totara crop ripens. Most CfOp in 1958; of the shrub-hardwood species fruit from March totara: light crops annually; to June but berries of some species such as mira and tawa (Beilschmiedia tawa): annual crops supplejack (Rhipogonum scandens), Coprosma fluctuating in quantity; robusta, broadleaf (Griselinia littoralis) and matai: no good seed crops, only a few seed on horopito (Pseudowintera spp.) may be avail- occasional trees from 1953 to 1962; fair CfOp in able throughout the winter. 1963; The hard-coated seeds of miro have taken hinau (Elaeocarpus dentatm) and rewarewa {Knightia at least three years to germinate in the F.R.I. excelsa}: good crops annually. nursery and some matai seeds have taken two Total yields of seed have been estimated for years (D. S. Preest pers. comm.). In forest, mature trees with deep, vigorous crowns con- seed of these species may remain dormant on sidered to have a heavy crop. Estimates for the ground for two or more years. Kahikatea individual trees in Pureora Forest, based on seed and most of the rimu and totara seed seed collections, are: dmu, 40 lb. ripe seed and germinates in the late spring and summer rcceptacles yielding 4 lb. of clean, sound seed after seed fall. (200,000); miro, 100 lb. ripe berries (32,000); SEED DISPERSAL BY BIRDS kahikatea, 1,800 lb. ri e seed and receptacles At Pureora there is a marked concentration yielding 300 lb. 0F clean, sound seed of fruit-eating birds during a good podocarp (4,500,000). In calm weather, comparatively fruiting season. The most active dispersers of few seeds of rimu, kahikatea or totara fall with podocarp seed are New Zealand pigeons the ripe receptacles still attached as many seeds (Hemiphaga novaeseelandiae), tuis (Prost he- and receptacles are eaten in the crowns of the madera novaeseelandiae) and bellbirds trees. (Anthornis melanura). These birds swallow Production and ripening of seed of the bath fleshy receptacles and seed of podocarps podocarp species may vary considerably in the but digest only the pulp, the seeds passing ~ame forest, even within areas of similar forest intact through the digestive tract. All three type, aspect, and altitude. The quantity and species eat the succulent fruits of a wide range quality of seed borne by individual trees in of shrub hardwoods. White-eyes (Zosterops any locality also varies greatly so that very lateralis) are the most common birds in the intensive sampling would be required to regrowth of logged forest at Pureora where they reliably estimate seed fall per acre. feed extensively on succulent fruits such as those of wineberry; they also swallow whole Shrub-hardwood species less succulent berries such as those of lance- wood (Pseudopanax crassifolium) and five- These appear to produce seed annually bul finger. the quantity varies according to forest type. During the fruiting season, pigeon droppings Species such as mahoe (Melicytus ramiflorus), may consist entirely of podocarp seed plus pate (Schefflera digitata) and fivefinger fibrous parts of the fruit. Large droppings (Neopanax arboreum) are present in dense attributed to pigeons have contained up to 100 podocarp forest but bear little seed except in kahikatea seeds or 12 matai seeds. Miro and large canopy gaps; in these forests, podocarp tawa seeds cleaned of pulp are dropped con- seed is the main food source for seed-eating tinually by pigeons feeding in fruiting trees; birds, rodents, and insects. When such forest thus mira seedlings are commonly found is clear felled, the regrowth consists mainly beneath tawa trees. After feeding, pigeons of berry-producing shrubs such as fuchsia may perch in nearby emergent trees of any (Fuchsia excorticata) and wineberTY (A risto- species, and large droppings found beneath telia serrata). these trees are probably from perching birds. 50 ANIMAL MODIFICATION OF NATIVE VEGETATION

Large kamahi (Weinmannia racemosa) in seed. The gut of a thrush (Turdus ericetorum) patches of low shrub hardwoods are frequently shot at the forest edge in May contained sound associated with groups of podocarp seedlings. kahikatea seed. Seeds found in pigeon droppings are always In a preliminary trial with mist nets set sound. up at the margin of Pouakani Forest, 22 birds were caught, including five white-eyes, five In 1960, an exceptionally heavy crop of blackbirds (Turdus merula) and two thrushes. kahikatea seed at Pureora afforded the oppor- Some of the fruit-eating birds had been feeding tunity to observe mass dispersal of seed from on tutu (Coriaria arborea), fuchsia, and virgin forest into adjacent cutover forest. Tuis Muehlenbeckia australis, and seedlings of all gathered in hundreds where kahikatea was these species were grown from seed contained dominant over 10 acres of a large block of in droppings of birds caged for a short period dense podocarp forest. There were also smaller before release. That 178 fuchsia seedlings numbers of bellbirds and pigeons. Residual were grown from the contents of a single trees in adjacent cutover forest were constantly dropping shows the importance of the black- visited by tuis in particular, and logs and bird as a seed distributor. stumps in the open to a distance of several Evidence of effective seed dispersal by birds chains from the forest edge were sprinkled over the past 50 years was obtained by a 2t% with sound kahikatea seed deposited by flying sampling of 160 acres of fire-induced second birds. These seeds were scattered or in drop- growth surrounded by virgin forest. Nearly pings containing up to five seeds plus recep- 80% of the i-chain-square quadrats were tacle skins and the small bracts characteristic stocked with seedlings and saplings of podo- of kahikatea fruit. All seeds were detached carp species, mainly rimu; some quadrats con- from their receptacles but most retained the tained as many as 40 stems over 6 in. high, strand of fibrous tissue that denotes dispersal dense groups often growing round old kamahi by birds. On 16 May most of the birds sud- stumps. denly moved away~ leaving smaller numbers well dispersed throughout the forest. DESTR UCTION OF SEED The presence of some large, deep-crowned Rimu. A large part of the rimu seed crop kahikatea at the natural forest edge near is destroyed during seed fall. At Pureora Pureora village enabled closer observation to Forest in 1958, 100 lb. of rimu seed and recep- be made of the feeding habits of both native tacles, collectcd frem hessian sheets laid on and introduced birds. Birds clearly seen to be the ground, yielded 10 lb. of clean, sound seed. feeding on ripe kahikatea fruit were tuis~ Some 40% of the seed was collecled after a pigeons~ white-eyes~ Indian mynas (Acrido- gale on 10 May had stripped trees of most of theres tristis), starlings (Sturnus vulgaris) their ripe seed; most seed8 fell with the fleshy and sparrows (Passer domesticus). Only the receptacles attached. At Minginui Forest tuis and pigeons were seen to swallow both during the same period, 100 lb. rimu seed and seed and receptacles and were therefore the receptacles yielded only 3 lb. of sound seed; only birds obviously acting as seed dispersers. many seeds were split and empty. (Elswhere, bellbirds have been seen to feed on Some rimu seed is destroyed on the crowns kahikatea; they probably disperse seed in the of the trees. Empty, split, crushed and frag- same way as tuis.) White-eyes pecked at the mented seed coats have been found in rodent- receptacles and often dropped seeds with rem- and bird-proof seed traps. From 20 May to 1 nants of ulp attached. Starlings and mynas August 1958, at Pureora, collections were made swallowe l the whole receptacle and often every fortnight from pairs of square-yard seed appeared to drop the seed from their bills traps placed beneath crowns of fruiting trees. immediately after detaching it. However, a One of each pair was covered with! in. wire starling shot in this locality had whole kahi- mesh and the other was left open. Counts katea seed in the gizzard. Starlings may dis- showed that during seed fall, proportions of perse some seed in flisht~ as they feed in an seed, receptacles, and fragmented seed coats excitable manner, movIng constantly from tree were similar in open and in covered seed traps. to tree, whether it is fruiting or not. Sparrows Table 1 shows that some 80% of the rimu seed merely extracted the juice by crushmg the collected in a covered trap from 20 June to receptacles, which fell still attached to the 3 July 1958 had been destroyed in the crowns. BEVERIDGE: DISPERSAL AND DISPOSAL OF PODOCARP SEED 51

TABLE 1. Condition of rimu fruit collected in falling from a tree with a light seed crop was a trap. destroyed by parakeets. These birds have also Number Percentage been seen eating seed of mountain toatoa of seeds of total (Phrllocladus alpinus) in January, the unripe Seeds with fleshy receptacles 44 1.5 receptacles being discarded. Seeds with undeveloped receptacles 284 9.6 Seeds without receptacles 289 9.8 Kaka destroy mira seed, often when berries Fleshy receptacles detached from are still green, by cracking them open and seeds 2,335 79.1 Fragmented seed coats many hundreds extrac6ng the seed contents; the two halves of the empty seed are dropped with the pulp The only excreta found in either open or still attached. closed traps were a few weta (Hemideina sp.) droppings. Rimu seeds do not normally become DESTR UCTION OF SEED BY RODENTS detached from ripe receptacles unless separated Caged specimens of the ship rat (Rattus by animals. rattus) have eaten quantities of podocarp seed, providing authentic samples of the type of Mira. The proportion of mira seed and fruit damage they do. Seed baits placed in Ihe forest from a single tree eaten between March and at Pureora showed that wild rats had the same September 1957 has been assessed. Counts were preferences for different podocarp species as made of seeds falling into a pair of square- caged rats. The order of preference was rimu, yard seed traps placed beneath a fruiting tree matai, mira, and kahikatea. Totara and tawa in Pureora Forest. One trap was covered with seed remained untouched. Fleshy receptacles ! in. wire mesh. Seed was placed in three of rimu and totara were quickly eaten, and categories according to its condition, as shown some kahikatea receptacles were taken. Cap- in Table Z. tive rats discarded the ripe pulp of mira berries . before gnawing through the hard seed coat to TABLE Z. Condition of mzro seed and fruit extract the kernel. In forest trials, a few mira from one tree. and matai berries were removed altogether OPEN COVERED from baits, presumably for eating at a more TRAP TUAP favoured site; piles of gnawed miro and hinau Total number of seeds ,..... 581 802 Condition of Seed Percentage Percentage seed have been found under logs and in other of total of total sheltered positions in the forest. On Pureora. Gnawed oc broken (contents mountain, small heaps of Hall's totara (Podo- eaten by rats oc kaka carpus haW;) seed have been found with rat (Nestor meridionalis}) ".... 22 26 Whole seed cleaned of pulp droppings; the receptacles had been removed. (dropped by pigeon) ...... 34 30 Whole berries ...... 44 44 In no case has the ship rat eaten the coats of podocarp seeds. These are split or gnawed, according to their size and hardness and the DESTR UCTION OF SEED BY BIRDS presence or absence of an easily opened suture At Pureora the only birds seen feeding on line, and the contents consumed. Thus rat rimu seed (as distinct from receptacles) have damage to mira and hinau seed is easily recog~ been Californian quail (Lophortrx californica) nised by the hole gnawed in the end or side and chaffinches{Fringilla coelebs); both species of the hard seed coat. Matai seed is split into were feeding on the ground in clearings. Quail halves or gnawed after the pulp has been eaten. shot in May have had some whole rimu seed Rimu and kahikatea seed are usually split in their crops. lengthwise but a few rimu seed coats may be fragmented, the damage being difficult to dis- Many birds eat the fleshy receptacles of tinguish from that presumably caused by kahikatea and totara but kahikatea seed falls finches. undamaged from the crowns, whether dropped by birds or not. The only bird observed There lllay be many rat droppings on hessian destroying totara seed has been the yellow- sheets placed on the ground beneath rimu crowned parakeet (Cyanoramphus auriceps), crowns but there are few in accessible seed which cracks the seed crosswise and extracts traps duriag the main seed fall. Rats turn to the contents, dropping the crushed seed coat. the seed in open traps from late winter. By In June 1958, up to 40% of the totara seed December, open traps with quantities of rimu FIGURE 1. Droppings of rats and insects: upper FIGURE 3. Kahikatea seeds: left-seed with left-ship rat, upper right-brown rat, lower ripe receptacles, centre-seed in pigeon drop- left-wetas, lower right-stick insects. pings, right~seed dropped by tuis. FIGURE2. Rimu seeds: left-after germination, FIGURE4. .Mira seeds: left-after germination, centre~opened by wetas, right--opened by ship right-opened by ship rats. rat. Photos by T. Ramfield, N.Z. Forest Service. BEVERIDGE: DISPERSAL AND DISPOSAL OF PODOCARP SEED 53

and kahiJwtea seed contain little but split, TABLE 3. Trapping results for ship rats in empty seed coats and rat droppings. Sound Pouakani Forest and brown rats on Mokoia miro or nJatai seed can rarely be found Island. beneath seeJ trees from September to March No. of No. of No. of but there are usually many gnawed seeds. Date of Forest trap rats rats per Gnawed miro seed and supplejack (Rhipogo- Trapping type nights caught trap night num seandells) fruit found in rodent-proof SHIP RATS May 1960 Ll 140 15 0.11 traps show that ship rats, which nest in trees M~ 140 17 0.12 and are good climbers, do feed in the crowns January 1962 L1 99 4 0.04 of trees. M2 77 2 0.03 May 1962 L1 40 9 0.22 There is no evidence of totara seed having M2 16 2 0.12 February 1963 L1 92 8 0.07 been eaten by :ship rats, either on the ground M2 210 2 0.01 or in open seed traps. Fallen kahikatea seed BROWN RATS usually remains undamaged until September March-April 1963 - 83 43 0.52 but after that much is destroyed by rats Mice are present in virgin high forest at beneath parent trees. Pureora but only five were caught in 814 rat- trap nights. There appear to be more in the On Mokoia Island, in Lake Rotorua, there is shrub ecotone at the forest edge and in monoao .,bundant evidence that seed and fruit of shrubs (Dracophyllum subulatum) heath; in these c:nd trees constitute an important part of the places, and in a store building, mice were food of brown rats (Rattus norvegicus). The trapped and rimu seed baits eaten. Both recep- i;land is covered with second-growth forest; tacles and contents of rimu seed were taken, there are no pod0carps except a few totara. only fragmented seed coats remaining; seed and Captive specimens of the brown rat from this fruit of other podocarp species were not eaten. locality ate no podocarp seed when alternative food was available. DESTR UCTION OF SEED BY PIGS AND OPOSSUM Examination of the stomach contents of a pig killed in Pouakani Forest in May revealed NUMBERS OF RODENTS IN FOREST LOCALITIES a large quantity of crushed hinau and matai and a little mira seed, together with aoofew whole berries. The ship rat has been caught in many In June, gnawed cotyledons of tawa seed different vegetation types near Pureora, indi- were found with fresh opossum droppings at cating that there is a fairly high population Minginui Forest. Berries had fallen two or in virgin forest. three months previously and the pulp had therefore rotted. A variety of baits and types of traps were used at first but these have since been standardised. In each of two types of virgin DESTRUCTION OF SEED BY INSECTS forest, rats are being trapped along a perman- At Pureora, destruction of immature matai ent line consistin~ of 20 traps spaced at one- seed by unidentified insects appears to be a chain intervals. The types being sampled are major cause of the constant failure of seed dense podocarp forest (Type LI, McKelvey crops. Flowering is often profuse but little and Nicholls 1957), in which kahikatea is seed reaches maturity. Immature fruit may be locally dominant, and mixed podocarp/tawa attacked by gall-forming insects in October, forest (Type M2). whilst in December the ground may be littered with green berries, most having insect exit Recently it has been found that there is a holes. dense population of brown rats on Mokoia Tree wetas must feed in the crowns of podo- Island. Traps have been placed at half-chain carps for droppings are generally found in intervals along lines leading inland from the raised seed traps. Weta droppings resemble water's edge. smaller droppings of the ship rat and have sometimes been confused with them. Captive Results to date for both species are shown wetas (Hemideina thoraciea) will eat both in Table 3. fleshy receptacles and contents of rimu seed, 54 ANIMAL MODIFICATION OF NATIVE VEGETATION

leaving fragmented seed coats with jagged The blackbird is an important seed disperser edges. Four captive wetas destroyed 109 rimu that has become adapted to a forest habitat. seed in a fortnight as well as some seed and It eats small-seeded berries, and has been seen foliage of Griselinia littoralis supplied as swallowing miro fruits (D. S. Preest, pers. alternative food. comm.). St. Paul (1960) recorded that 60 The abundant droppings of stick insects in blackbirds were feeding on matai fruit at seed traps placed beneath rimu trees indicate Minginui on 14 March. that these insects are present in rimu crowns Some birds that usually drop podocarp seed in considerable numbers when fleshy recep- whilst feeding on the ripe receplacles may tacles have developed on the rimu seed, but occasionally disperse seed by swallowing it, or it is not known whether they eat receptacles detaching it in flight. Starlings appear to act or seed. in this way. St. Paul (1952, 1956) has noted J. S. Dugdale of the Forest Research Insti- that thousands of starlings gathered to feed on tute has reared ten species of insects from heavy crops of kahikatea fruit in 1951 and tawa fruit but the larvae of only one species, 1955 at Minginui. the moth Cryptaspasma querula, were found The presence of certain shrub species in to be eating the fleshy cotyledons that consti- subalpine scrub may depend on bird dispersal tute the bulk of the seed. of seed from fruiting specimens at lower alti- DISCUSSION AND CONCLUSIONS tudes. On Pureora mountain (3,800 ft.) Dacrydium bidwillii and Phyllocladus alpinus In central North Island forests there are in the subalpine scrub have shown no sign of usually some species fruiting at all times of fruiting in recent years, and spread mainly by the year although fruit is scarce in spring; the vegetative means, while specimens on the greatest quantity is available from March to plateau at 1,800 ft. have often fruited well. June. The volume of sound podocarp seed The frequency of rimu seedlings well above produced fluctuates markedly from year to the limit of mature trees shows that extensive year but some species have seed that can dispersal occurs up the mountain. At 2,500 ft. remain sound for one or more years, thus rimu has borne green seed, but ripe seed has providing a long-term food source for rodents. not been observed. Seed of most podocarp species cannot be The relative importance of rodents, birds, distributed more than one or two chains from and insects in the destruction of a large portion the crowns without the aid of birds, except of the rimu seed crop has not yet been deter- possibly by water. Many of the native birds mined. It is suspected that finches eat rimu that are probably seed dispersers have become seed in the tree crowns, particularly chaffinches, rare, e.g. the kokako (Callaeas spp.), saddle- lesser redpolls (Carduelis flam mea) and green- back (Philesturnus carunculatus), and New finches (Chloris chloris), but confirmation is Zealand thrushes (Turnagra spp.). However, required from examination of crop and stomach species such as pigeons, tuis, and bell birds are contents. At Pureora chaffinches enter deep sti11 dispersing large quantities of seed in into the forest and flocks are present through Pureora and Pouakani Forests. There is a the winter and greenfinches have been marked movement of fruit-eating birds to observed at the forest margin. Redpolls were areas ,",vherecrops are heavy. overlooked until P. C. Bull pointed out that White-eyes are the most numerous distri- they were present at the forest edge in January. butors of small-fruited species but some small Small quantities of rimu seed could be des- birds such as robins (Mira australis) and tits troyed in tree crowns by ship rats, wetas and (Petroica spp.), generally considered to be parakeets. The role of insects in the destruc- mainly insectivorous (as in Oliver 1955), may tion of rimu seed has not been adequately distribute seed. Thus Watson and Bull (unpub.) studied. ' have suggested that the South Island robin The only native birds observed destroying may do this in Westland, where they observed seed have been kaka and yellow-crowned para- it feeding on fleshy receptacles of rimu. The keets. Although both these species may be writer has seen a pied tit carrying a beITY of seen or heard daily at Pureora they are not Coprosma parviflora. The Lake Monk expedi- present in sufficient numbers to cause a serious tion to Southern Fiordland (Riney et al. 1959) amount of damage to seed, at least in a good recorded that the yenow-breasted tit was seen seed year. Characteristic damage is caused to feeding on ripe, small-leaved coprosma fruits. miro and totara seed. ANIMAL MODIFICATION OF NATIVE VEGETATION 55

Rats eat a large part of the seed falling seed by birds is vital for the regeneration of beneath parent trees of all the main podocarp scrub areas situated more than a chain or so species except totara; for species other than from fruiting trees. rimu most of this destruction takes place after the main seed-fall period. To judge from rat ACKNOWLEDGEMENTS droppings and broken rimu seed found on Assistance received from the following per- hessian sheets, much rimu seed must be eaten sons is gratefully acknowledged: Messrs. E. by rats during seed fall. Moreover, comparison H. Bunn and D. S. Preest of the Forest of seed in open and in rodent-proof seed traps, Research Institute, and Dr. K. A. W odzicki of and the small number of rat droppings in the the Animal Ecology Division, D.S.I.R., for former, shows that little podocarp seed is eaten criticism of the manuscript; Mr. M. .T. Daniel in accessible traps during the main seed fall. of the F.R.I. for assistance with trapping of Possibly rats are reluctant to enter seed traps rodents. Some of the observations in this paper while there is still plenty of seed on the confirm findings of earlier unpublished work ground. Bird-dispersed seed is less likely to by Mr. Bunn, who studied podocarp seed fall be destroyed, since rats would naturally con- at Pureor" from 1955 to 1957. centrate on feeding beneath seed trees. Trapping hitherto indicates a fairly steady SUMMARY population of rats at Pureora but the data are Seed-crop studies carried out over the past six years show that there is a marked periodicity in fruiting too meagre to allow conclusions to be drawn amongst some podocarp species but that shrub hard- about seasonal fluctuation in numbers. No woods fruit annually. Some berries and dormant seeds trapping has yet been done in spring, when 'ire ovailable throughout the year as a food source for an increase in numbers could occur after a birds, rodents, and insects. During a good fruiting season podocarp seed is effectively dispersed in Pureora good seed fall. Forest by pigeons, tuis, and bellbirds, sometimes in There are few records of trapping of rodents local concentrations. Blackbirds, thrushes, and starlings in other areas of indigenous forest. Watson can also disperse podocarp seed. and Bull (unpub.) working in Westland dur- Part of the rimu seed crop is destroyed on the tree ing poor weather, trapped only one rat in 192 crowns, probably by finches, and a large part on the ground by ship rats, which are numerous and wide- rat-trap nights and four mice in 105 mouse- spread in forest near Pureora. Kahikatea seed is not trap nights. No rats were trapped during the damaged on the tree crowns, but fallen seed is eaten Lake Monk expedition. by ship rats. Mira, matai, and hinau seed is eaten by ship rats and wild pigs, and miro seed is eaten by: More figures are needed before the impor- kakas. Totara seed is not eaten except by parakeets. tance of rats as destroyers of forest-tree seed Podocarp seed that falls beneath crowns of parent trees can be assessed. Seed of various indigenous when birds eat the fleshy receptacles does not contri- species is being fed to captive specimens of bute to regeneration of the forest. Much fallen tawa both the ship rat and the brown rat to find seed is destroyed by larvae of the moth Cryptaspasma querula, and it is also eaten by opossums. out how much they can eat. Despite the many seed-destroying animals, there has It appears that tawa seed is not eaten by rats heen proI.ific germination of rimu and kahikatea seed under natural conditions, at least where there in the summer following a heavy seed fall. is alternative food. A major destroyer of REFERENCES fallen tawa seed at Pureora is the moth HINDS, H. V., ..:ind HElD, .J. S., 1957. Forest trees and Cryptaspasma querula. It is also suspected that timbers of New Zealand. N.Z. For. Servo Bull. 12. wild pigs eat freshly fallen tawa fruit. The McKELVEY, P. J., and NICHOLLS, J. L., 1957. A pro- destruction of tawa seed on the ground by visional classification of North Island Forests. N.Z. opossums has not previously been recorded J. For. 7: 84-101. OLIVER, W. R. B., 1955. New Zealand Birds. A.H. find and this may occur only when a high deer A. W. Reed, Wellington. population has destroyed most of the under- RINEY, T., WATSON. J. S., BASSETT, C., TURBOTT, E. G., storey species, as at Minginui. and HOWARD, W. E., 1959. Lake Monk Expedition. Despite the many seed-destroying agents in D.S./.R. Bull. 135. ST. PAUL, R., 1952. Classified summarised notes, Notornis central North Island forests, there appears to 4, 196. be no lack of germinating seed after a good ST. PAUL, R., 1956. Classified summarised notes. Notornis seed year. Young seedling regeneration of 6, 212. kahikatea is usually prolific. Many small ST. PAUL, R., 1960. Classified summarised notes. Notornis seedlings of podocarp species, however, are 7, 213. WATSON, J. S., and BUl.L, P. C., 1956. (Unpub.) ephemeral and seedlings do not become estab- Report on a visit to Westland. Animal Ecology lished beneath parent trees. Dispersal of sound Division, D,S.I.R.