Advances in New Zealand mammalogy 1990-2000: Wallabies

f. Journal of The Royal Society of New Zealand,
Volume 31, Number 1. March 2001, pp 7 14

Advances in New Zealand mammalogy 1990-2000: Wallabies
R. M. F. Sadleir* & B. Warburton**

1. DAM A WALLABY

Macropus eugenii (Desmarest, 1817)

Description
Incisor and molar wear was described by Lentle et al. (1998a). As dama age, the molar teeth
row moves forward and the incisor cutting surface changes from the anterior to the lateral
upper incisors. The usual method of age determination for dama, the molar index, uses the
correlation between age and the forward movement of molars in the jaw past a base line
between the anterior rim of the orbits. Lentle et al. (1998a) question this method, because the
base line itself changes position in the skull as dama age. They recommend instead using a
correlation between age and increasing distance from the front upper molar to the jaw joint
along the premolar/molar occlusion.

Distribution
New Zealand
The distribution of dama in the Rotorua area continues to expand (compare Fig. 1 with the
map given by Sadleir & Warburton 1990). The preferred habitat of dama, the border of forest
or scrub with pasture, is widespread in the greater Rotorua area, particularly south and west
of the Paeroa range, but that does not explain the slow rate of expansion.
   The expansion of range to the southwest means that dama now occupy land under the
administrative control of two separate regional councils, Environment Bay of Plenty and
Environment Waikato.

Food
Lentle et al. (1998) used neck collars carrying microphones and radio transmitters to measure
feeding activity in free-ranging dama wallabies. They confirmed that dama are, broadly
speaking, crepuscular and spend more time grazing than browsing. Dama grazed for an
average of 6.5 hours per night on pasture, longer in forests; in both habitats, they foraged less
in bad weather. In a parallel study on captive dama, Lentle et al. (1998b) found that the length
of time spent feeding was inversely related to the nutritional quality of the food offered. Neck
radio-microphones showed that dama near Rotorua spent an average of 343 ± 33 minutes per
day (n=4) chewing food (Lentle et al. 1999).
   Lentle et al. (1998c) carried out a detailed morphometric study of the alimentary canal in

* 120 Sweetacres Drive, Belmont, Lower Hurt, New Zealand. Email: rsadleir@paradise.net.nz
** Landcare Research, PO Box 69, Lincoln, New Zealand. Email: warburtonb@landcarc.eri.nz

1   I

                                                                                                         Bay of Plenty

                                                                                                                                            5'

                               RQTO^U
                                                                                                                                            ft1

 i   TOKOROA

                                                                                                                                            I
                                                                                                      Wallaby Distribution
         \   \
                                                                                                                    1979
             V                                                                                                      2000
             l«                                                                                             *       Confirmed Sightings
                                                                                                     5          0      5    10 Kilometers

Fig. 1 Distribution of dama wallabies in the Rotorua area. Data from Environment Bay of Plenty (unpubl.). It is possible that the 1979
boundary was somewhat conservative, so the apparent rate of expansion to 2000 may appear exaggerated (P. Commins, pers. comm.).

Sadleir & Warburton—Wallabies              9

a large sample of dama shot on a single night. The lengths and tissue weights of the various
gut sections were all proportional to the overall body weight. However the length of the
caecum, as a proportion of the body weight, was more typical of browsing species than of
grazing species. Female dama tended to have a relatively larger stomach and caecum, and
relatively longer caecum and colon, than males.
   Analysis of stomach contents showed that dama ingested smaller-sized food particles than
do larger macropods - perhaps in order to reduce the time necessary for gut food fermentation
(Lentle et al. 1999a). Chewing rates, as determined by the neck microphone, were typical of
other small herbivores. The rate was slower while browsing than grazing, with a higher
chew-to-bite ratio, but in either case, dama are relatively inefficient food handlers, judging by
their wastage.
   Captive damas drank water when fed on dry pelletised food, but not when fed on carrots
(Lentle et al. 1999b), suggesting that in the wild they do not need to drink when they are
feeding on fresh vegetation. Where water is limited, dama seem to prefer more succulent
plants even if of low nutrient value, rather than drier plants that are more nutritive.

Social organisation and behaviour
Radio-revealed home ranges of dama in the Rotorua area varied between 10 and 39 ha
(Lentle et al. 1999). This study was conducted just after a control operation, when there
should have been plentiful food available. The largest dama had the largest home ranges, and
the ranges of males tended to overlap those of several females. At dusk and dawn, females
tended to graze close to the bush edge for long periods, but a single male ranged much more
widely. Dama habitually used the same few daytime resting sites, and made clear trails from
them to the grazing areas.
   During the day, dama associated in small groups, males with females and females with
juveniles. In the evening the group emerged from the bush together. Maximum distances
moved from the site of original capture over the subsequent six months were as follows: adult
males 1950 m; adult females 1000 m; juvenile males 1100 m; juvenile females 1550 m.
   Microphone studies confirmed that females sometimes emitted a deep screeching call, of
unknown function, usually while moving out of cover to graze.
   During daylight (Lentle et al. 1999) dama rested in a "sitting tail forward" position, with
the tail outstretched forward between the legs. At night they lay on one side with the head on
the ground.
   The sedentary habits of wild dama seem little affected by re-capture, handling and release.
On a farm at a lake edge in the Rotorua area, most individuals stayed within 50 m of their
original release site. Many radio-collared dama were recaptured several times over a long
period at almost the same location as their original capture.

Reproduction and development
The overall sex ratio of dama on Kawau Island was not significantly different from unity
(Sunnucks & Taylor 1997), but the pouch young of heavier females were significantly more
likely to be male (logistic regression (%2 = 16.8,/3 < 0.0001). This observation is consistent
with the hypothesis (Trivers & Willard 1973) that well-provisioned females should bias their
output towards the sex that would benefit most from extra resources, provided those resources
can increase reproductive success of their offspring at maturity.
Predators, parasites and diseases
A single captive dama in India had well-developed tuberculosis (Mycobacleria tuberculosis),
with firm grey nodules in the liver, spleen and lungs (Rao et al. 1991). Consequently Lentle

10      Journal of The Royal Society of New Zealand, Volume 31, 2001

et al. (1999) carried out postmortems on 98 dama shot over a single night at Okataina reserve
near Rotorua, but found no macroscopic lesions in any spleen or liver.

Significance to the New Zealand environment
Control
Warburton (1990) used 1080 poison mixed with carbopol gel as bait, smeared on the foliage
of palatable plants in the Rotorua area. From faecal pellet counts, he estimated an 87%
decrease in dama numbers in the treated area. The costs of a control operation using the 1080
foliage gel ($8.50 per ha) were favourable compared with aerial 1080 baiting ($11.90 per ha),
but gel would be considerably more expensive in areas with difficult ground access. Later
work by Dale Williams (pers. comm.) used 1080 applied to carrots distributed from the air
over a 1300 ha block near Lake Okataina, which achieved an estimated kill of 93-96%.
    Williams (1997) evaluated bait stations for dama control. The Marley downpipe " Hockey
stick" station was preferred by dama, but they were reluctant to feed from the "Philproof'
bait feeder. Where possums (Trichosurus vulpecula) were numerous and aggressive, they
effectively displaced wallabies from feeders.
    Captive dama observed by Lentle et al. (1999) strongly preferred carrot baits over high-
energy pellets containing maize and barley. When a low-energy pellet bait was included in
the trial, the rates of consumption were highest for carrots, intermediate for low-energy
pellets and lowest for high-energy pellets. Free ranging dama were never seen to eat standard
possum baits (Mapua No 1), even when grazing on grass littered with them.
   The Animal Pest Management Strategy for the Bay of Plenty Region (Environment Bay of
Plenty 1998) considers that dama should be controlled because they damage indigenous
vegetation. The Council has a long-term goal (p. 22) " to contain and reduce the dama
wallaby feral range" by encouraging the work of land occupiers, who are responsible for
controlling dama populations on their land. The regional Pest Management Strategy for the
Waikato Region (Environment Waikato 1996) has a similar goal for the areas within its
jurisdiction where wallabies are present, at Tumunui and in pockets at Ngahuru and Waikiti.The
Auckland Regional Pest Management Strategy (Auckland Regional Council 1997) aims to
confine wallabies to Kawau Island, the location of the only population of dama in the
Auckland Regional Council region. The Council also aims to promote community awareness
of the impact of dama on other native species and, in the long term, to eradicate dama from
the region.
    Small numbers of dama have been live-trapped over the past thirty years for export to
overseas zoos (David Moore, Environment Bay of Plenty, pers. comm.).

2. BENNETT'S WALLABY

Macropus rufogriseus rufogriseus (Desmarest, 1817)

Distribution
New Zealand
A recent sighting (2000) of three Bennett's wallabies in the valley of the North Branch of the
Godley River (Graham Sullivan, Environment Canterbury, pers.comm.) suggests that this
species is extending its range to the northwest by natural means. However it is possible that
these individuals were released there.

Sadleir & Warburton—Wallabies             11

Significance to the New Zealand environment
Control
Warburton (1990) used 1080 poison in a carbopol gel, spread on palatable foliage, to control
Bennett's wallaby in the Tasman Smith Scenic Reserve, Hunters Hills, South Canterbury.
Wallaby numbers were reduced by 91 %, estimated from the reduction in faecal pellet counts.
Foliage gel costs $7.90 per ha, whereas the more commonly used aerial baiting using 1080
pellets cost $ 21.60 per ha. However, Warburton emphasised that foliage baiting would be
more expensive over larger areas and where foot access is difficult.
   Warburton & Frampton (1993) compared methods used to assess the relative density of
wallabies in the Hunters Hills of South Canterbury. The overall variation in the percent
frequency of faecal pellets in plots along transect lines was quite low, so a sample of only five
lines (100 plots per line) could detect a statistically significant change in pellet density of
20%. There was good repeatability of counts over time, and between observers. Regular
counts of wallabies from the air along helicopter transects were also cost-effective and
consistent. Staff from Environment Canterbury had previously used a visual method for
estimating wallaby abundance, called the Guilford Score. Observers compared pellet
distribution to pellet patterns printed on small cards. Warburton & Frampton's pellet counts
and the helicopter counts both correlated well with the Guilford Score, so they recommended
continued use of the Guilford score, since it is the simplest available method.
   The objectives of the Regional Pest Management Strategy in the Canterbury Region
(Environment Canterbury 1998) are to reduce wallaby densities to or below Guilford Score 4,
and to prevent the spread of existing wallaby populations beyond the present area bounded by
the Rangitata River, Lake Tekapo, Tekapo River and the Waitaki River. The western
boundary of wallaby distribution between Lake Tekapo and the Rangitata River is presently
unclear.

3. PARMA WALLABY

Macropus parma Waterhouse, 1845

Population dynamics
The sex ratio of parma wallabies on Kawau Island at the last survey was not significantly
different from unity (Sunnucks & Taylor 1997) and, although the trend was not significant
due to small sample size, the offspring of Macropus parma were more likely to be male as
maternal weight increased.

Significance to the New Zealand environment
Control
The objectives of the Regional Animal Pest Management Strategy of the Auckland Regional
Council (Auckland Regional Council 1997) include: (1) to confine parma wallabies to
Kawau Island; (2) to promote community awareness of their impact on other native species;
and (3) in the longer term, to eradicate parma wallabies from the region.

12      Journal of The Royal Society of New Zealand, Volume 31, 2001

5. BRUSHTAILED ROCK WALLABY

Petrogale penicillata penicillata Griffith, 1827

Distribution
New Zealand
Until they were eradicated in the late 1990's, rock wallabies were concentrated along the
coast and in the western part of Rangitoto Island (Szymanik 1987). They have also been
eradicated from the adjacent Motutapu Island, which is joined to Rangitoto by a sand isthmus
at low tide.

Food
From faecal and stomach content analysis and observations on grazed vegetation, Szymanik
(1987) concluded that rock wallabies on Rangitoto Island were selective feeders concentrating
mainly on pohutukawa and rata (Metrosideros spp.), Coprosma spp. and several types of
grasses. Five other species were regularly eaten: Griselinia lucida,Astelia banksii, Bleclmum
capense and two unidentified species. Occasionally Cythodes spp., Geniostoma ligustrifolia,
Pteridium aquilinum and Pseudopanax arboreus were also taken. Carcases examined had a
lower level of fat than expected, suggesting that the lack of grasses on Rangitoto was a
serious deficit for the wallabies. Bad weather often inhibited movement across the causeway
to pastures on Motutapu Island, implying that when Rangitoto wallabies were forced to
browse on shrubs rather than to graze, they were not getting an adequate diet.

Social organisation and behaviour
Rock wallabies observed by Szymanik (1987) on Rangitoto Island were almost completely
nocturnal. The mean nightly foray lengths on Rangitoto were similar between sexes (males
199 m, females 265 m) and longer than previously found on Motutapu (males 123 m,
females 101 m). These data are all based on repeated trap captures, and are probably
underestimates. Night observations showed frequent passages across the causeway between
the islands. In September and October, except in bad weather, usually at least 40 wallabies
crossed at sunset to Motutapu. Szymanik assumed they returned at sunrise.
   Home ranges on Rangitoto Island tended to be much larger than on Motutapu Island, even
though the sample sizes were small:
                           Rangitoto Island           Motutapu Island
                           Szymanik 1987               Batchelor 1980
Males                      6387 m2 (n=2)                922 m2 (n=4)
                                   2
Females                    3325m (n=l)                  510nr(n=6)
   On Rangitoto Island, rock wallabies made their dens in dense vegetation and were
repeatedly radio-tracked back to the same dens (Szymanik 1987)
Reproduction and development
Rock wallabies on Rangitoto Island bred at a lower rate than on Motutapu. Females on
Motutapu had pouch young in every month of the year (Batchelor 1980), but on the adjacent
Rangitoto, Szymanik (1987) found pouch young only from January to September, and then
only in half the adult females sampled.

Predators, parasites and diseases
Two species of boopid lice, Heterodoxus ampullatus and Boopia notofusca, were found on a
brushtailed rock wallaby from Kawau Island (Palma 1996). These are the first species of lice

Sadleir & Warburton—Wallabies               13

specific to marsupials reported in New Zealand. From the distribution of H. ampullatus in
Australia, Palma suggested that the Kawau population might have originated from the
southern part of the rock wallaby's native range in eastern Victoria.

Significance to the New Zealand environment
Control
In 1990 the Department of Conservation (DOC) mounted a campaign to eradicate both
possums (Trichosurus vulpecula) and brushtailed rock wallabies from Rangitoto Island,
because of the extensive damage both species were doing to pohutukawa (Metrosideros
excelsa) forests there. Control on the connected Motutapu Island was done at the same time,
but was easier because that island was mainly farmland with little forest cover. On 5 and 6
November 1990, 28 tonnes of 6g 1080 baits were spread over Rangitoto from the air
(Pekelharing 1991). Studies of the baits immediately after sowing showed they retained their
size and physical integrity for over two weeks (Eason et al. 1991). The relative abundance of
wallabies was estimated before (August and September 1990) and after (November) the
drop. Systematic spotlighting over designated segments of the road round the island recorded
mean counts of 15.7, 28.4 and 1.8 wallabies seen per section, respectively. From these data
Pekelharing estimated a 93% kill. He also marked 15 pairs of transects throughout the island.
Before the aerial baiting, cyanide baits were placed at unspecified intervals along one of each
pair of transects, killing a total of 41 wallabies over two nights. After the aerial drop, a similar
cyanide baiting on the paired transect killed no wallabies (Pekelharing 1991). As expected,
the 1080 levels were initially high in one wallaby carcass recovered after the operation, but
the 1080 concentration then rapidly declined to low levels in 29 days. No 1080 was
discovered in surface or ground waters (Eason et al. 1991).
    Throughout the rest of the 1990's, DOC carried out intensive ground operations against
rock wallabies on Rangitoto, using baits, traps and hunting with dogs. In 1999 a helicopter
survey using forward looking infrared detection (FLIR) found no wallabies on the island
(J. Coates, DOC, Auckland, pers. comm.). DOC now considers that rock wallabies have been
eradicated from Rangitoto and Motutapu Islands.
    The objectives of the Auckland Regional Pest Management Strategy (Auckland Regional
Council 1997) include: (1) to confine the last population of rock wallabies in the region to
Kawau island; (2) to promote community awareness of the impacts of wallabies on other
native species; and (3) in the longer term, to eradicate all wallabies from the region.

REFERENCES
Auckland Regional Council 1997: Wallabies. In: Auckland Regional Pest Management Strategy.
   Auckland, Auckland Regional Council. Pp. 41 —43.
Batchelor, T. A. 1980: The social organisation of the brush-tailed rock wallaby (Petrogale penicillata
  penicillata) on Motutapu Island. Unpublished MSc thesis, University ot Auckland.
Eason, C. T.; Batcheler, D.; Wright, G. R. 1991: Environmental impact and post-control assessments on
   Rangitoto Island after possum and wallaby control, November 1990: Fores! Research Institute
   Contract Report: FEW 91/9, for Department of Conservation Auckland. Christchurch, Forest
   Research Institute.
Environment Bay of Plenty 1998: Animal Pest Management Strategy for the Bay of Plenty Region .
   Dama wallaby. Whakatane, Environment Bay of Plenty. Pp. 21-22.
Environment Canterbury 1998: Proposed Regional Pest Management Strategy, Bennett's wallaby.
   Christchurch, Environment Canterbury. Pp. 20-22.
Environment Waikato 1996: Regional Pest Management Strategy: Operative 1996-2001. Dama wallaby.
   Hamilton, Environment Waikato. Pp. 94—95.
Lentle, R. G.; Potter, M. A.; Springett, B. P.; Stafford, K. J. 1999: Bait consumption and biology of
   tammar wallabies in the Rotorua region. Conservation Advisory Science Notes No 221, 18 p.
   Wellington, Department of Conservation.

14       Journal of The Royal Society of New Zealand, Volume 31, 2001

Lentle, R. G.; Potter, M. A.; Stafford, K. J.; Springctt, B. P.; Haslctt, S. 1998: The temporal characteristics
   of feeding activity in free-ranging tammar wallabies (Macropus eugenii Desmarest). Australian
   Journal ofZoolog}' 46: 601-613.
Lentle, R. G.; Stafford, K. J.; Potter, M. A.; Springett, B. P.; Haslett, S. 1998a: Incisor and molar wear
   in the tammar wallaby (Macropus eugenii Desmarest). Australian Journal of Zoology 46: 509-527.
Lentle, R. G.; Stafford, K. J.; Potter, M. A.; Springett, B. P.; Haslett, S. 1998b:The temporal character
   of feeding behaviour in captive tammar wallabies (Macropus eugenii Desmarest). Australian
   Journal of Zoology 46: 579-600.
Lentle, R. G.; Stafford, K. J.; Potter, M. A.; Springett, B. P.; Haslett, S. 1998c: Factors affecting the
   volume and macrostructure of gastrointestinal compartments in the tammar wallaby (Macropus
   eugenii Desmarest). Australian Journal of Zoology 46: 529-545.
Lentle, R. G.; Stafford, K. J.; Potter, M. A.; Springett, B. P.; Haslett, S. 1999a: Ingesta particle size,
   food handling and ingestion in the tammar wallaby (Macropus eugenii Desmarest). Australian
   Journal ofZoolog}' 47: 75-85.
Lentle, R. G.; Stafford, K. J.; Potter, M. A.; Springett, B. P.; Haslett, S. 1999b: Temporal patterns of
   drinking in the tammar wallaby (Macropus eugenii Desmarest). Australian Journal of Zoology 47:
   67-73."
Palma, R. L. 1996: First records of marsupial lice (Insecta: Phthiraptera; Boopidae) on a brushtailed
   rock wallaby from New Zealand. New Zealand Journal of Zoology 23: 161-164.
Pekclharing, C. J. 1991: Changes in possum and wallaby numbers following an aerial control operation
   on Rangitoto island in 1990: Forest Research Institute Contract Report; FEW 91/2, for Department
   of Conservation, Auckland. Christchurch, Forest Research Institute.
Rao, A. T.; Acharjyo, L. N.; Upidhyaya, T. N.; Baliarsingh, S. K.. 1991: Generalised tuberculosis in a
   wallaby (Macropus eugenii). Indian Journal of Veterinary Pathology 15: 43^14.
Sadlcir, R. M. F. ; Warburton, B. 1990: Family Macropodidae. In: King C. M. ed. The handbook of
   New Zealand mammals. Auckland, Oxford University Press. Pp. 34-67.
Sunnucks, P.; Taylor, A. C. 1997: Sex of pouch young related to maternal weight in Macropus eugenii
   and M. parma (Marsupialia; Macropodidae). Australian Journal ofZoolog)' 45: 573-578.
Szymanik, M. L. 1987: The ecology of the brush-tailed rock wallaby (Petroga/e penicillata penicillata)
   on Rangitoto Island. Unpublished MSc thesis, University of Auckland.
Trivers, R. L.; Willard, D. E. 1973: Natural selection of parental ability to vary the sex ratio of
   offspring. Science 179: 90-92.
Warburton, B. 1990: Control of Bennett's and tammar wallabies in New Zealand using compound 1080
   gel on foliage baits. Australian Wildlife Research 17: 541-546.
Warburton, B.; Frampton, C. 1993: Monitoring Bennett's wallaby in south Canterbury. Landcare
   Research Contract Report: LC9293/112, for Canterbury Regional Council. Christchurch, Manaaki
   Whenua - Landcare Research.
Williams, D. 1997: Evaluation of bait stations and management options for control of dama wallabies
   (Macropus eugenii) in the Bay of Plenty, New Zealand. University ofOtago Wildlife Management
   Report 85. Dunedin, University of Otago. 87p.