Lizards in the Garden

Forest and Bird, Issue 294, 1 November 1999, Page 14

Lizards in the Garden

TONY WHITAKER

New Zealand gardens host a variety of lizards and

tells how to attract them.

or most suburbanites the first evidence there are lizards in the neighbourhood is when the family puss coughs up a pile of mutilated corpses on to the shag-pile. After cleaning up the mess the curious will wonder where they came from because, for most people, lizards are the unseen inhabitants at the bottom of the garden. Yet, with more than 70 recognized species, New Zealand has one of the highest diversities of lizards of any temperate area on earth. There are 37 geckos (baggyskinned lizards) and 35 skinks (smoothskinned species) occupying various habitats from the shore to more than 2,000 metres up the mountains. It is hardly surprising, then, that at least some have been able to adapt to life in urban environments. Not for us, however, are those translucent house geckos boldly running upside-down across the ceiling as in the tropics, or gathering in noisy groups around the lights at night. Instead, our lizards are rather secretive and timid creatures, more comfortable well out of sight, in dense vegetation, beneath leaf litter or hiding in the dark recesses of our houses. Nevertheless, in total, 12 species of gecko and at least seven species of skink have been reported from suburban environments (see box opposite) though some of these are rare in such places. The lizard species inhabiting suburban environments vary in different parts of the country, but most are skinks. Throughout the North Island, the secretive Cyclodina species can be found, largely nocturnal and occupying overgrown, damper sites. Their presence is usually detected when debris or dense vegetation is cleared. In the southern North Island and the

South Island are the day-active Oligosoma species that prefer drier, sunny sites. These may be glimpsed as they scurry for cover when disturbed. Common geckos (species of the Hoplodactylus maculatus complex) sometimes occur in sheds or older houses, forming populations that live for many generations in the roof or beneath the floor. These nocturnal animals are seldom seen but tell-tale signs of their presence are their droppings — small white lumps of uric acid, or the papery, white pieces of skin shed several times each year. In outer suburbs, gardens bordering native bush or scrub may be home to tree-dwelling green geckos (Naultinus species) and forest geckos Hoplodactylus granulatus, but their superb camouflage means they will rarely be seen. To encourage lizards in the garden it is important to know their needs. To observe them requires patience and an understanding of their behaviour. The essential things in a lizard’s life are secure cover and food. Day-active skinks also require sheltered basking sites. Highly ordered and tidy suburban gardens are no place for lizards as these conditions are not met. However, if you have an overgrown garden, or ‘wild’ places on your property, there are things you can easily do to encourage lizards to establish themselves or to enhance the populations that might be present. All lizards require a place to hide when inactive, and to protect them from predators and extreme weather. Cold, heat and dehydration are critical factors in their survival. Lizards also need cover to shelter them from predators while they search for food. The kinds of places lizards use for retreats, and when foraging, vary between species, however. Natural retreats include cracks in the ground or banks, places beneath logs or rocks, dense vegetation (e.g. the bases of flax plants), crevices in trees, or under bark. Materials for artificial retreats for lizards are limited only by your imagination — consider using planks, corrugated iron, bricks, or concrete. Remember, it is not the material but the size of the sheltering object that is significant. The protective object should exceed 20 centimetres square and its distance from the ground should be no more than 5-8 millimetres). Lizards like to squeeze themselves into a tight space just wider than their body thickness to feel contact with both their back and belly. Anything too far from the

What to look for, and where he lizard species inhabiting suburban gardens vary widely throughout the country. The lists below are just a guide to what to expect in different places. Remember anything can turn up, especially in rural gardens, as happened recently when a Coromandel resident found a striped gecko Hoplodactylus stephensi in his bedroom — the first North Island record for this exceedingly rare and endangered species! In Auckland: Though copper skinks Cyclodina aenea and ornate skinks C. ornata are widespread in the city, their secretive and largely nocturnal habits mean they are not often seen. Day-active rainbow skinks Lampropholis delicata, introduced from Australia, are much more conspicuous inhabitants. In outer suburbs (e.g. North Shore, Henderson, Titirangi), gardens adjacent to native forest or scrub remnants may also have green geckos Naultinus elegans, forest geckos Hoplodactylus granulatus and Pacific geckos H. pacificus. Wellington: Copper skinks are prevalent but ornate skinks are very localised and rarely seen. The most widespread lizards in the city are the daytime common skinks O. nigriplantare polychroma and brown skinks Oligosoma zelandicum. Common geckos Hoplodactylus maculatus are relatively abundant in coastal suburbs (e.g Island Bay, Miramar). In hill suburbs (e.g. Karori, Eastbourne, Hutt Valley), gullies with native forest or scrub are occupied by forest geckos and green geckos. Christchurch: The only lizard within the city is the common skink. In suburbs along the Port Hills and at Lyttleton there are also Canterbury geckos (an undescribed species related to Hoplodactylus maculatus). Jewelled geckos Naultinus gemmeus occur in remnants of native forest or scrub. Dunedin: The southern city fares least well for suburban lizard populations. Only common skinks live in urban areas but in outer hill suburbs, and in the small communities along the Otago Peninsula, jewelled geckos occur in native scrub and forest remnants, sometimes in exceptional abundance. Other places, and surprises: Less commonly reported from city and town gardens are moko skink Oligosoma moco (North Shore), spotted skink O. lineoocellatum (Kaikoura, Christchurch), McCann’s skink O. maccanni (Alexandra), Marlborough green gecko Naultinus manukanus (Picton), Nelson green gecko Naultinus. stellatus (Nelson), and two as yet undescribed species related to Hoplodactylus maculatus (Wellington, Kaikoura and Alexandra).

ground or firmly embedded in soil is unsuitable. Lizards, especially skinks, are territorial so it is important to provide enough habitat and enough retreats for a population to establish. Each lizard requires several square metres of space. As each lizard will also use different retreats at different times, sheltering objects should be well scattered through the whole area. If artificial cover is placed in thick vegetation, or amongst ground-cover plants, it also provides a surface where diurnal skinks can bask. Basking sites must be in the sun for several hours each day. A material like stone that absorbs and retains heat is ideal, and the surface should be orientated to face directly to the sun. Several different basking sites may be needed so lizards can follow the sun during the day. Skinks seek food within the protective cover of dense vegetation: to venture on open surfaces like paths or lawns is far too risky. Even well-weeded flower beds are too bare. To provide suitable foraging areas, allow parts of your garden to become completely overgrown. Whether with groundcover plants, weeds or rank grass is immaterial, but the greater the variety the more

10 ways to encourage lizards in the garden e Get rid of the cat and dissuade other cats from visiting the garden. e Encourage thick plant growth on banks, in borders and along hedgerows. e Mulch heavily and encourage a build-up of deep leaf litter. e Place logs, planks or bits of corrugated iron where plants can grow around or over them. e Make rockeries with many loosely placed stones (not firmly embedded in soil) or create stone heaps. e Use dense ground-cover plants. e Leave numerous cracks when building stone or block walls. e Plant berry or nectar producing species, especially native divaricating shrubs. e Allow vines on buildings to reach the roof so geckos can easily get in and out. e Minimise or eliminate pest spraying so that insect populations increase. e Don't keep a cat.

likely there will be a diverse invertebrate fauna as lizard food. All lizards are primarily insectivorous and eat any invertebrates they can overpower, including beetles, flies and caterpillars. Spiders are a special favourite, but lizards are not fond of slaters. Nocturnal geckos love moths. Any gardening practice that promotes a proliferation of invertebrate life — such as reducing or eliminating pest spraying, and using deep mulches and ground-cover plants — ultimately benefits lizards. In summer day-active skinks and geckos eat lots of sweet juicy berries and soft fruits like kawakawa Macropiper excelsum. Good natives to plant are divaricating Coprosma_ species, pohuehue vines (Muehlenbeckia) and porcupine bush (Melicytus alpina or M. crassifolius). These plants bear fruits within densely tangled branches that help protect foraging lizards from predators and are easy to climb. Geckos are also particularly fond of nectar so flax, pohutukawa or other species producing copious nectar should be planted. Many introduced birds and mammals kill lizards but easily the most serious -especially for urban lizards — are cats. Cats have been found with over 30 lizards in their stomachs, representing just 4-6 hours hunting. If you really want to encourage lizards in your garden you should not keep a cat and should discourage other cats from visiting your property. Failing that, be sure to provide plenty of secure cover where lizards can forage and hide. Cyclodina skinks prefer to hunt at night and require humid conditions. They favour foraging in sites with dense moist, ground cover and deep leaf-litter, preferably beneath shrubs or trees. To encourage these species, mulch heavily or promote the accumulation of leaf-litter. Also plant vigorous ground-cover species. Planks, logs or rocks are the best material for retreats as they retain moisture. Conversely, Oligosoma skinks prefer drier, more open habitats away from the cover of trees. The best sites for them are sunny banks with dense ground cover of rank grass or low herbaceous species. Heatretaining surfaces are favoured for basking sites, and pieces of corrugated iron are good for artificial retreats because heat readily transfers through them. Common and Pacific geckos like dark, dry retreats during the day; at night they forage on trees, banks or buildings. Retreats can be in buildings — often in the roof between the building paper and roofing iron to take advantage of warmth from the sun. They also like stacks of corrugated iron or planks, squeezing into narrow gaps

to be secure from predators. In more natural situations these geckos hide in dry crevices in trees, banks or walls. Old pohutukawa trees provide excellent shelter with their deeply furrowed bark. Another favoured retreat site is the ‘skirt’ of dead leaves on cabbage trees. To encourage green and forest geckos into your garden do not ‘clean’ thin or open up native bush and scrub. These geckos need the protection offered by dense foliage, tangled branches and dense ground cover such as stick litter and ferns. It will even help these strictly forest-dwelling geckos if you promote thick tangles of vines such as pohuehue (Muehlenbeckia australis or M. complexa). Never introduce lizards to your garden. All New Zealand lizards are fully protected and it is against the law to capture them or move them to another place. Furthermore, bringing a lizard from another place — say, the skink your children see at the beach — would probably be moving it to a completely unsuitable habitat. If your garden is a suitable habitat for lizards they will prob-

ably be there already, and all they will require to thrive and multiply is that the habitat is improved. If you enhance the habitat lizards will populate your property from elsewhere in the neighbourhood anyway. Remember — a clean and tidy garden is not a good place for lizards. If you fancy harbouring lizards, get rid of the cat, let the plants run wild, scatter around some artificial cover, and before long you will probably be rewarded with a glimpse of a skink. Sit quietly and you will be able to watch these fascinating little creatures go about their daily lives.

Taranaki's special town dweller he rarest lizard to regularly occur in urban habitats is the goldstripe gecko Hoplodactylus chrysosireticus. These small geckos (total length about 14 centimetres) are known only in the area from Taranaki to Mana Island, near Wellington. The Department of Conservation rightly regards them as threatened (Category C priority), but Taranaki residents might well wonder why — goldstripe geckos occur in New Plymouth and several smaller towns such as Waitara, Stratford and Opunake. In natural habitats or gardens, the goldstripe gecko seems to prefer flax, though the lizards are equally at home on species with similarly dense foliage — cabbage trees, toitoi, or cultivated plants such as agaves, yuccas, or red-hot pokers. The geckos hide by day amongst the leaf bases and forage at night to the tips of the leaves and flower spikes. Occasionally they can be seen by day sunning themselves close to cover. In secure and protective habitat goldstripe geckos have been able to adapt to urban life and attain locally high population densities close to the heart of a major provincial city.

TONY WHITAKER is a herpetologist and consulting ecologist based in Motueka. The krait, or sea snake, is from Vanuatu, but specimens wash up on New Zealand shores occasionally,