After a trial field season at SSSI 8 (now ASPA1 1282; a Site of Special Scientific Interest situated near the Polish Antarctic Station Henryk Arctowski) in 1999, which predominantly served to test equipment, recording methods and visiting regimes, recordings for THIS STUDY were obtained at SSSI 13 (now ASPA 1323) in two consecutive years (2000, 2001) during the second halves of two incubation periods (mid- to end of November until the beginning of December). The respective maps are found in chapter 3, figs. 3-21 and 3-22.
To minimise bias due to observer impact, the study was designed to be predominantly hands-off.
It was conducted on incubating penguins to facilitate distinction between the locomotory and the emotional component of heart rate changes (BLIX, STRØMME & URSIN 1974; BROOM & JOHNSON 2000) by keeping the former component to a minimum. To account for individual variation in resting heart rate as well as for susceptibility of heart rate to climatic conditions (cf. CULIK & al. 1989), each individual served as their own control (BALDOCK & SIBLY 1990).
4.1 Equipment
4.1.1 Behaviour/ Posture Data
For detailed behaviour recording, a video camera (Sony Handycam® Video Camera Recorder CCD-TR2000E Hi8/ PAL) was placed on a tripod out of sight of the penguins at a distance of approximately 25-30 m from the colony edge (fig. 4.1). Behaviour of the incubating penguins as well as of any conspecifics in the vicinity was recorded on tape (Hi8 video tapes, 90 min) and transcribed after the fieldwork periods. On the videos, the time of recording was shown in the bottom right corner. In addition to the electronic recording equipment, field binoculars (Leica, 8x20) and a field scope (Danubia Z-12; zoom: 12-36X50) were used for direct observations (e.g., identification and position of Focal-Animal nests to facilitate recognition during transcriptions).
Direct observations were collected in a field notebook.
1 Antarctic Specially Protected Area (q.v.)
2 Admiralty Bay, King George Island (= Isla 25 de Mayo), South Shetland Islands, Maritime Antarctic 3 Maxwell Bay, King George Island (= Isla 25 de Mayo), South Shetland Islands, Maritime Antarctic
Figure 4-1: Behaviour Recording Equipment: The Video Camera.
Behaviour of the penguins was filmed from inside a tent approx. 25-30 m away from the colony edge.
4.1.2 Heart Rate Data
4.1.2.1 The Artificial Egg
The artificial eggs used in THISSTUDY were developed at Imperial College, London, and first employed by NIMON & al. (1994). They represent a technique for the non-invasive monitoring of heart rate in incubating penguins by use of an infrared sensor implanted in the egg rather than ‘planted onto’4 the penguin themselves. The sensor makes contact with the incubating penguin’s highly vascularised brood patch and registers the pulse-varying volume of blood flow (fig. 4-2).
4.1.2.1.1 Construction Details
As described in NIMON & al. (1996), the shell of the artificial egg was originally modelled from a paper maché cast of a discarded Gentoo penguin (Pygoscelis papua) eggshell. To provide greater strength and waterproofing the paper surface was coated with three layers of fibreglass and epoxy resin. The finished egg (7.5 x 6 cm) was painted white (matt paint). Due to the smaller size of Adélie penguin eggs, the artificial eggs had to be downsized and repainted prior to employment in
THISSTUDY.
The infrared sensor is mounted beneath a small transparent acrylic plastic window (1 cm in diameter) set in the long lateral side of the egg and flush with the surface. The sensor and its associated low-voltage electronic circuitry were housed in a plastic tube for ease of replacement.
The tube is embedded in the egg interior, and the screened power/ signal cable leads out through the long side of the egg opposite to the sensor. At its outlet the cable is clamped with metal washers and epoxy resin. All components within the egg are sprayed with insulating lacquer. To achieve complete waterproofing and to provide both weight and further impact protection, the remaining space in the egg is filled with RTV5-sealant.
The cable leading to the egg is passed through a small wooden board (10 cm diameter) that sits immediately beneath the egg in the nest. This construction ensures that the egg maintains a fixed orientation, with the sensor facing up to the brood patch. The board and the base of the egg are buried in the gravel of the nest when the egg is implanted and the cable is passed through the nest’s wall. In this position, it does not affect the nesting penguin. In order to maintain a simple, robust system that would perform reliably in Antarctic conditions, cable was preferred over radio telemetry (e.g., HOWEY
& al. 1984). To prevent inadvertent ensnarement of other penguins, the remainder of the cable is hidden underneath or between rocks.
4 or inside
5 RTV: short for room temperature vulcanising
Figure 4-2: Heart Rate Recording Equipment I.
Schematic construction of an artificial egg. Redrawn after NIMON (1997).
The following facts continued to hold true for the eggs used in THISSTUDY. As the ‘& al.’ in NIMON &
al. (1996) comprised the developers of the artificial egg, the experts are quoted rather than rephrased.
“The infrared sensor used to monitor heart rate was a UFI6 photoelectric pulse transducer (model 1020) consisting of a matched emitter and photo resistor. When placed close to the skin of the pouch [= brood patch], the reflection of the infrared light was modulated by blood pulsing through the subcutaneous tissues. The modulation of light resulted in a small change in resistance of the photo resistor; this was monitored as a change in voltage that, when amplified, produced a high-level voltage output in the cable of approximately 1 volt peak to peak. The dynamic response characteristics of the sensor were far in excess of the cardiac pulsations. The sensor and associated electronics were powered by a remote 12-V battery supply.” (NIMON & al. 1996, p. 1020)
The modulation properties of the infrared beam are sensitive to movement: If the penguin remained prone (lying), movements such as shuffling (gently rocking on the egg to achieve a more comfortable position) or stretching, temporally distorted the record, while longer bouts of activity (getting up to manipulate eggs or to preen), produced longer passages of illegibility.
The power/ signal cable (length: 10 m) from each egg leads to a remote multiconnection box (which collects the signals of up to four eggs) and then, via a 50 m cable to the data logger. The purpose of the two multiconnection boxes used was to allow up to eight eggs to be monitored in parallel. Generally, heart rate of focal birds of the same group was monitored at the same time (two to three eggs in parallel). As the focal birds’ behaviour was simultaneously videotaped, it was possible to relate these physiological responses with behaviour.
In some instances, heart rate from birds of groups not currently video-recorded was additionally monitored to acquire on-the-spot information on heart rate responses from more than one group (e.g., predator presence between two groups; response at ‘never-visited’ group A to visitation at other groups). These records were only accompanied by manually noted (un-taped) behavioural observations (ad lib.) and were not included in systematic analyses.
4.1.2.1.2 Placement Procedure
Placement procedure followed description in NIMON & al. (1996): A single person approached the nest slowly, remained an arm’s length away and kept low to avoid ‘looming’ above the penguin7. The artificial egg was secured inside the penguin’s nest by burying the platform and part of the height of the egg in the stones and gravel of the nest. The cable thus protruded through the wall.
After reshaping the nest to its original position, the artificial egg resembled a natural penguin egg in the nest.
In THISSTUDY, placement of the artificial egg took on average 2.5 min. Even though the bird was free to leave the nest during placement, the majority of focal animals remained seated. Those who chose to get up stepped only a few metres away, and returned while the human intruder crouched quietly, enabling them to be paint-marked (water-based paint) with a long-handled brush. After a period of reconnaissance fieldwork in 1999 it became clear that blue markings were the only ones that stood any chance to stand out among the ‘natural paint marks’ the breeding birds quickly acquired in the course of their long stint of incubational occupation (these included any shades of
6 UFI Inc.: capital letters do not constitute an acronym; instrument-manufacturing company in California, USA 7 … As FRID & DILL (2002, p. 11) put it: “Many animals initiate flight when the rate of change of angle subtended by an
approaching object (‘loom’) exceeds some threshold.”
yellow, orange, pink, red, purple, brown, green, and grey bordering on black). For video-recognition of the nests containing artificial eggs, the nest number was painted on a stone which was placed close to the nest.
4.1.2.1.3 Hardware and Software Requirements
As mentioned above, cables served to connect the artificial eggs with the data-storing device. A data logger (TTi8 pod) was employed to feed the data stream recorded by the artificial eggs into a laptop (ASUS L8400). Two spare laptop batteries helped to counteract swift loss of battery power caused by low temperatures in the field. To power the artificial eggs, two power stations (Power Station, titan Autozubehör) were employed alternately.
8 TTi: Thurlby Thandar Instruments Ltd. in Cambridgeshire, UK
Figure 4-3: Heart Rate Recording Equipment II. Information collected in the artificial eggs was fed into the computer via a data logger. The software programme TTi VIPS enabled the observer to continuously monitor the quality of recordings. On the right hand side, the battery needed to power the artificial eggs is seen within its ‘protective garment’.
The software programme TTi VIPS (Virtual Instrument Pod System, VIPS 203a) transformed the incoming data stream into voltage values. The data stream channelled through the logger was auto-saved in pre-numbered files (.prn- or .log-format) by the programme. The observer merely decided on the name of the first file, and determined the number of file-breaks. Saving one file and opening another every couple of minutes resulted in some intermittent data loss which, however, was accepted in favour of manageable file sizes. Recording rate varied between 8 data points (dp) per second (s-1; i.e., one data point taken each 125 ms) and 100 dp s-1 (each 10 ms). On those occasions in 2000, during which a field assistant acted as visitor, recording rate was augmented to 200 dp s-1 (each 5 ms). Throughout the recording, heart rate was displayed on-screen for continuous monitoring (fig. 4-3). The lowest recording rate sufficed with respect to visualising heartbeats (fig. 4-4), but as the software had a tendency to infrequently omit one or more data points, it was considered prudent to increase data points per second.
Figure 4-4: Heartbeats per 20 s as Depicted by a Recording Rate of 125 ms. The x-axis gives the time of recording, while the y-axis displays voltage. More data points per second traced the course of each heartbeat more closely.
4.1.3 Human Disturbance Data
For each visit, visitor number, behaviour and movements were written down in a field notebook or on pre-prepared sheets. To synchronise visitor data with behaviour and heart rate data, exact times (to the nearest second) were determined by a digital wristwatch checked against video and computer time prior to the beginning of each visit.
4.1.3.1 A Single Visitor
In the first field season in ASPA 132 (formerly SSSI 13; Potter Cove), the impact of a single visitor was examined. For eight visits (four each at groups B and C, respectively), another scientist volunteered to act as visitor. She/ He received detailed instructions as well as the procedure sheet (chronology of the visit in written form) prior to approaching the penguins. For the remainder of the time, there was no field assistant available; and the observer ‘doubled’ as visitor on these occasions.
4.1.3.2 The ‘Visiting Trio’
In the second field season in ASPA 132 (Potter Cove), the impact of a group of three visitors was examined. As it was unlikely that more than one (if any) field assistant(s) would be available at any time, two artificial visitors were created (fig. 4-5). The dummies were fastened to the frame of a dismantled backpack and could thus be carried by the ‘mobile visitor’ (observer).
4.1.4 Conspecific Disturbance Data
Data on conspecific disturbance were recorded on video tape (s.a., section 4.3.2).
4.1.5 Predator/ Aircraft Disturbance Data
Data on predator or aircraft disturbance were recorded on video tape (s.a., 4.3.2). Aircraft noise was additionally entered into the field notebook.
4.1.6 Weather Data
A total of six weather parameters were collected (s.b., section 4.2.7) with the following equipment:
Wind speed and direction were measured by a hand-held anemometer which provided
measurements in Beaufort, knots, and km h-1 (ANEMO, Fa. Deuta, Germany). Temperature at ground level and at 0.5 m above ground was taken with the help of a digital thermometer situated outside direct sunlight. Estimated cloud cover and precipitation were noted in a field notebook.