Temperature inside nest-boxes of Little Penguins.

Brief description

In order to assess the potential impact that artificial nest boxes may have on the occupation rate or physical condition of adults and chicks of little penguins (Eudyptula minor), temperature was recorded continuously from 24 August 2002 (0000 hours) for 37 days inside 7 nest boxes and in surrounding bush on Penguin Island, Western Australia.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: We recorded temperature data from 24 August 2002 (0000 hours) to 1 October 2002 (2300 hours) within a colony of approximately 1,000- 1,200 little penguins nesting on the central part of Penguin Island (32 17'S, 115 41'E), Rockingham, Western Australia (see thumbnail). The sand is too soft for burrows, here Penguins nest in caves of limestone, rock crevices, and under bushes growing on the Island. We recorded temperature inside and outside 7 nest boxes, which were placed along a transect orientated W-NW running approximately along the seacoast. The island was open to tourists between about 1000-1600 hours from May-September, but people had no direct access to the nest boxes. The rectangular plywood boxes, 0.9 x 0.4 x 0.4m, had a removable roof and were surrounded by bushes of sea spinach (Tetragonia decumbens) and true spinifex (Spinifex longifolius). We determined an index of solar exposure using the percentage of the surface of the box (roof and 4 sides) that was in the sun at noon on the day of logger deployment. We used 12-bit-resolution, 16-megabyte-memory, 2-channel UME-TT loggers (Little Leonardo, Tokyo, Japan) to record temperature every minute. Each of these silver, titanium-housed, cylindrical loggers
(102 x 20mm, 14g in the air, absolute accuracy for temperature 0.1oC) had 2 thermosensors located at the end of 27.5cm cables that emerged from the end of the logger body. We attached all loggers using marine Tesa tape (Beiersdorf AG, Hamburg, Germany) inside nest boxes, against a wall. We attached inside sensors close to the ground and attached outside sensors on a branch inside the surrounding bush as deep as the cable length permitted (approx. 5-10cm inside the bush). In addition to the data recorded by the loggers, we obtained meteorological data (including average temperature, wind speed and direction, humidity), collected every 3 hours at the meteorological station of Garden Island (32 23'S, 115 68'E), from the regional office of Perth, Commonwealth Bureau of Meteorology, Australia. Sunset and sunrise occurred at approximately 1800 and 0600 hours local time, between 24 August and 1 October 2002 (Bureau des Ephemerides, Paris, http://www.bdl.fr/).

Temperature difference
(Td) was defined as: Td = Ti - To

where Ti and To stand for the temperature values recorded inside and outside of the nest-boxes, respectively. A positive Td represents a temperature inside the box higher than that outside. We first averaged temperatures recorded by loggers on an hourly basis, then averaged on a daily basis. To compare effects of humidity on the temperature variations, we selected the 2 days with the highest and lowest average percentage of humidity (9 and 29 September, respectively) using the meteorological data collected at Garden Island. Similarly, we determined the day with the strongest and weakest wind speeds (14 and 20 September, respectively) using average wind-speed values calculated on days for which >70% of the daily wind data recorded were orientated between 140 degrees SE - 310 degrees NW. We checked occupation of boxes by breeding little penguins (i.e., presence of 1 or 2 adults with eggs or chicks) on the first day of logger placement. On the first day, 3 boxes were occupied: B30 had 1 adult and 1 egg, and both B27 and B19 had 1 adult and 2 eggs. We found adult pairs without eggs in boxes 64 and 23 on the first day of logger placement, but they were not seen in the box in the 2 subsequent days.

Notes

Credit
Japan Society for Promotion of Science, Tokyo, Japan and Murdoch University, Perth, Australia.

Purpose
To help in the conservation and management of Little Penguins