Field Methods

Almost two-thirds of the skinks caught within the study area and all skinks caught elsewhere were caught by hand. Active searching accompanied by turning or lifting of rocks, bricks and any other readily movable objects within the collecting areas exposed skinks which could then be taken by hand. This method was generally more effective when temperatures were sufficiently low to slow down the movement of the animals.

Two traps of the pitfall type were tested. The first of these, a wide-mouth glass preserving jar sunk in the ground so that the top of the jar was flush with the surface, was unsuccessful, probably due to poor siting. Few captures occurred even when the trap was baited with rotting fruit to attract flies. This type was subsequently abandoned. A serious disadvantage of this trap was the tendency to fill with water in wet weather, a problem overcome with the second type of trap adopted, which consisted of a six-inch length of galvanised iron downpipe, 3 inches in diameter, buried as before with its upper lip flush with the surface of the ground. The lower open end allowed water to quickly drain away, and an inch or two of soil filled the bottom of the trap. This soil was soon colonised by a variety of amphipods, isopods and insects, providing an abundant food supply for trapped skinks. Skinks were observed on more than one occasion to examine the interior of the trap, stretching out and looking down into the bottom, before dropping down to the soil beneath.

Both types of trap were covered with a slab of rock or brick supported above the trap lip so as to leave ample room for a skink to enter. A serial number painted on the inside of each trap was used in recording the location of capture of each lizard.

The lizards were marked by clipping the toes in various combinations. Generally no more than three toes were clipped with a maximum of two toes on any one foot. The toes were removed close to the second joint with a pair of fine-pointed scissors. Any toes lost through natural causes were incorporated as conveniently as possible into the marking system. In no case were the toes found to regenerate. The method proved to be very satisfactory; the only difficulty experienced occurred in cases of toes lost through natural causes subsequent to marking. These were often plainly apparent as the marked toes were cut at a constant point and those lost naturally rarely coincided.

The marking of each skink was carried out in the field immediately upon capture or removal from a trap. The trap number, or the point of capture together with any other relevant details, was recorded at the same time. All skinks were then carried in cages to the laboratory for weighing and measuring.

Laboratory Method

The weight, together with a series of measurements for each lizard, was taken in the laboratory. All measurements were made in millimetres to the nearest 0.5 of a millimetre, and recorded on individual index cards. Each lizard was laid in the supine position and held at the mid-body point with the fingers of both hands. The skink was then gently stretched out by stroking towards the head and tail. This process was repeated for up to three or four minutes if necessary, until the well known state of false hypnosis shown in many species of lizards was induced. Juveniles can be quieted in a shorter time than adults. The small size of L. zelandica rendered this method necessary. The method gave consistently good results.

Each lizard was weighed on a laboratory scale, to the nearest tenth of a gram. Some difference between weights recorded for the one lizard at short intervals may have been due to the presence or absence of food in the skink's alimentary tract. In most cases, however, each animal was held in captivity for 24 hours without food before weighing.