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Posture

N. b.: Phases bordering onto missing data were only included in counts for phase durations, if they exceeded 20 s

4.3.3 Heart Rate Data

4.3.3.1 Transcription of Heart Rate

Focal-animal heart rate evaluations served to examine the intra-individual extent of consistency (across sessions) as well as the range of differences between individual penguins (synchronous recordings) with respect to their physiological reactions when subjected to similar sources of potential disturbance (i.e., human visitation, conspecifics, and predators/ aircraft). A third aim was to compare for each bird their heart rate reactions towards humans with those displayed towards conspecifics.

4.3.3.1.1 Datasets Transcribed

As described for transcriptions of behaviour responses (section 4.3.2.4), heart rate transcriptions included recordings of entirely undisturbed birds (mainly group A), recordings of birds disturbed

‘only’ by conspecifics and/ or predators, and recordings during which a human visit occurred (generally on top of conspecific disturbance). The first two are jointly referred to as ‘baseline’

sessions. Recordings including a visitation event could be separated into three distinct periods, viz., pre-, during-, and post-visitation, with the first period completely comparable to ‘baseline’

scenarios, while the third period lacked the direct influence of the human disturbance stimulus, but was potentially influenced by its after-effects.

Excluding unidentified focal animals and single records obtained from identified focal animals, heart rate records from a total of 88 sessions were transcribed for focal-animal analyses. In 2000 (30 min-sessions; 11 FA), records comprised 26 visitation and 31 ’baseline’ sessions. The respective figures for 2001 (45 min-sessions; 5 FA) amounted to 12 visitation and 19 ’baseline’ records. Table 4-15 gives a comprehensive overview of sessions transcribed per focal animal.

4.3.3.1.2 Assignment of Nests

In accordance with the policy of minimum-impact, the artificial eggs had been inserted into nests of the first or second rows52. As already mentioned, the birds resident on the nest during placement of the artificial egg had been paint-marked (with the exception of two nests, viz., nests B33 and C1153), and could thus be distinguished from their naïve partners. As preliminary analyses revealed substantial day-to-day variation between heart rate (and behaviour) of individuals, but no consistent differences between birds that had or had not been present during placement of the artificial egg, this distinction is not referred to in analyses.

4.3.3.1.3 Primary Transcription Procedure

Prior to transcription, the original heart rate files were resaved in .xls-format, and 20 s-graphs were created (amounting to 90 graphs for each 30 min session; 135 graphs for each 45 min session).

As depicted in figure 4-11, heart rate signals varied in overall form, voltage and amplitude54. While it was possible for a human brain to extract the relevant information from different ‘types’ of heart rate signals, the computer programme designed for this purpose sadly failed to accomplish that feat. For transcriptions used in comparison with results from behaviour element evaluations, 20

s-52 These could be approached from the edge of the colony so that placement of artificial eggs did not require entering the colony.

53 for whom only the distinction between ‘prior-to’ and ‘after’ egg-insertion could reliably be made until a change-over was observed

54 To some extent this is caused by the position of the bird’s brood patch relative to the window of the artificial egg.

intervals of heart rate were thus manually counted (i.e. 5,130 graphs for 57 sessions à 30 min, and 4,185 graphs for 31 sessions à 45 min).

Table 4-15: Numbers of Sessions Transcribed for Focal-Animal Heart Rate Records. FA: focal animal; A, B, C, X, Y: study groups of penguins; 2000, 2001: year of data collection, [group-nest]-3: unidentified incubator; no: no fieldwork possible; dc: discarded for various reasons; no egg: no artificial egg inside nest; vis: human visitation occurred; unvis: no human visitation occurred; numbers in brackets: sessions excluded from analyses. (page 1 of 2)

Figure 4-11: ‘Real-Time’ Heart Rate of Two Focal Animals (B3-2, B4-1). For each focal animal, 20 s of heart rate, representing the counting interval used, are depicted. As can be seen, the signals vary in overall form, amplitude, and absolute voltage. FA: focal animal.

Heart rate recordings transcribed and analysed per FA; from sessions with (purple) and without (turquoise) human visitation

Day and Month

FA (Year) 12 Nov. 13 Nov. 14 Nov. 15 Nov. 16 Nov. 17 Nov. 18 Nov. 19 Nov. 20 Nov. 21 Nov. 22 Nov. 23 Nov. 24 Nov. 25 Nov. 26 Nov. 27 Nov. 28 Nov. 29 Nov. 30 Nov. 01 Dec. 02 Dec. 03 Dec. 04 Dec. sum recor- dings ob-tained per

FA A5-1 (2000) unvis no 1 1 no 1 1 1 no 1 1 1 1 1 no no 10 A5-2 (2000) unvis no no no 1 1 no 1 dc no dc 3 A5-3 (2000) unvis dc dc dc no no no no no 0 A6-1 (2000) unvis dc no no dc 1 dc no 1 dc no 1 dc no dc 3 A6-2 (2000) unvis 1 no 1 1 no no 1 1 no no 5 A6-3 (2000) unvis dc no no no dc dc dc no no 0 B3-1 (2000) vis 1 no no no 1 1 no no 3 B3-1 (2000) unvis dc no no no 1 no no 1 B3-2 (2000) vis 1 no 1 1 no 1 1 no no no 5 B3-2 (2000) unvis no no 1 no 1 no no 2 B3-3 (2000) vis no no no dc dc no dc no dc 0 B3-3 (2000) unvis no no no dc no dc no 0 B4-1 (2000) vis dc dc no 1 dc no 1 1 no no no 3 B4-1 (2000) unvis dc no no 1 no no no 1 B4-2 (2000) vis no no no 1 1 dc dc no dc no dc 2 B4-2 (2000) unvis no no no 1 dc 1 no dc no 2 B33-1 (2000) vis no no no dc no dc no dc 0 B33-1 (2000) unvis no no no dc no dc no 0 B33-2 (2000) vis no no no no no no egg B33-2 (2000) unvis no no no no no no egg

Table 4-15: Numbers of Sessions Transcribed for Focal-Animal Heart Rate Records. (page 2 of 2)

4.3.3.1.4 Heart Rate in Conjunction with Behaviour Elements – Outline of Secondary Transcriptions

Manually counted 20 s-values were extrapolated to beats-per-minute (bpm) and correlated with results on behaviour elements, posture, and disturbance which had likewise been evaluated for 20 s-intervals (tab. 4-21; summary in chapter 5.2.3; paper in 5.2-1).

Heart rate recordings transcribed and analysed per FA; from sessions with (purple) and without (turquoise) human visitation

Day and Month

FA (Year) 12 Nov. 13 Nov. 14 Nov. 15 Nov. 16 Nov. 17 Nov. 18 Nov. 19 Nov. 20 Nov. 21 Nov. 22 Nov. 23 Nov. 24 Nov. 25 Nov. 26 Nov. 27 Nov. 28 Nov. 29 Nov. 30 Nov. 01 Dec. 02 Dec. 03 Dec. 04 Dec. sum recor--dings ob-tained per

FA C1-1 (2000) vis 1 dc no dc 1 no 1 dc no 1 no no 4 C1-1 (2000) unvis dc no no dc no 1 dc no no 1 C1-3 (2000) vis no no no no no no egg C1-3 (2000) unvis no no no no no no egg C2-1 (2000) vis dc dc no dc no no dc no dc no dc 0 C2-1 (2000) unvis dc no no no (1) no dc no no analyses C2-2 (2000) vis no 1 no 1 1 no 1 1 1 no no 6 C2-2 (2000) unvis no no 1 no 1 1 no no 3 C11-1 (2000) vis no no no 1 1 dc no 1 no dc 3 C11-1 (2000) unvis no no no dc no dc no 0 C11-2 (2000) vis no no no no no no egg C11-2 (2000) unvis no no no no no no egg

X1-1 (2001) vis 1 1 1 no no no 3

X1-1 (2001) unvis 1 1 2 dc no no no 4

X2-1 (2001) vis 1 1 1 no no no 3

X2-1 (2001) unvis 2 1 2 1 no no no 6

X2-2 (2001) vis no no no 1 1 2

X2-2 (2001) unvis no dc no no 1 2 3

X3-1 (2001) vis dc dc no no no 0

X3-1 (2001) unvis dc dc no no no 0

X3-2 (2001) vis dc no no no (1) dc no analyses

X3-2 (2001) unvis dc dc no dc no no dc dc 0

Y4-1 (2001) vis dc dc (1) no no no no analyses

Y4-1 (2001) unvis dc dc (1) (1) no no no no analyses

Y5-1 (2001) vis 1 1 1 no no no 3

Y5-1 (2001) unvis 1 1 2 1 no no no 5

Y5-2 (2001) vis no no no 1 dc 1

Y5-2 (2001) unvis no 1 no no dc 1

Y6-1 (2001) vis dc dc no no no 0

Y6-1 (2001) unvis dc dc (1) no no no no analyses

Y6-2 (2001) vis dc no no no dc dc 0

Y6-2 (01) uv

2001: delayed arrival in the field

dc no dc no no dc

end of field-work

0 sum of heart rate recordings transcribed and analysed: 88 (2000: 57; 2001: 31)

recordings during unvisited sessions: 50 (2000: 31; 2001: 19);

recordings during visited sessions: 31 (2000: 26; 2001: 12)

total number of FAs (excl. unid. and single- or zero-session birds: 16 (2000: 11; 2001: 5)

4.3.3.1.5 Heart Rate Topography – Outlook on Secondary Transcriptions

In conjunction with behavioural topography (q.v.) evaluations which examined the ‘flow’ of behaviour, a different approach was needed to reflect accompanying heart rates. Rather than extrapolating to beats-per-minute values (bpm), heart rate counts per 20s were plotted ‘as counted’. The reader is asked to keep in mind that for comparison with published studies the respective values need to be multiplied by three. Representation of focal-animal heart rate generally depicted ‘real 20 counts’ (heartbeats counted for 20 s), and, in some instances, 30 counts calculated to fit 20 s-requirements (see explanation in section 4.3.3.1.6).

n Qualitative Overview: Visual Appraisal of Changes in Heart Rate during Human Visitation and/or Conspecific Presence

For visual appraisal, pre-visit heart rate (comprising approximately 10 min per session) was classified as either ‘undulating regularly’, increasing or decreasing across five 2 min-intervals.

During-visit as well as post-visit heart rate was then compared to pre-visit heart rate (increasing/

decreasing/ no change; see tab. 5.3.1-5, in Methodological Prelude, chapter 5.3.1.1).

n Comparison of Variation in Heart Rate before, during, and after Human Visitation with Variation in ‘Baseline’ Heart Rate

Apart from looking at between-period changes in heart rate (e.g., for mean or maximum values obtained), analysis of the magnitude of heart rate variation was extended to not only include visited sessions but also ‘baseline’ sessions, i.e. sessions without human visitation. This way, it was possible to additionally compare heart rate variation across periods (before, during and after human visitation) with variation recorded for successive 10 min-intervals (without any human interference).

Comparisons of heart rate variation were analysed using a total of 8 statistical parameters (chapter 5.3.2.1).

n Distribution of Phase Durations of Heart Rate before, during, and after Human Visitation

Mean Resting Heart Rate (RHR) was determined (chapter 5.3.3.1), and RHR ±2 SD was taken as the ‘tolerance band’ for delineating three heart rate categories used for further analyses: below RHR ±2 SD, within RHR ±2 SD, and above RHR ±2 SD (NEEBE & HÜPPOP 1994; also see ELLENBERG

& al. 2006, 2009).

Heart rate phases constituted lengths of time spent in a given category. Phase durations invariably lasted (multiples of) 20 s. In case of overlaps, i.e. phases across period boundaries, the entire phase was assigned to the period within which its greater proportion had occurred55.

Heart rate phase durations were assigned to three duration classes, each of which was divided into three subclasses. Accommodating 20 s-intervals and a greater range (than behaviour phases), the classes presented in table 5.3.3-4 (chapter 5.3.3.1) resulted.

4.3.3.1.6 Missing Data

Three phenomena accounted for the greatest part of lost data: 1. Overwriting (technical/ computer-based error), 2. signal death (electronic systems failure), and 3. signal obfuscation (illegibility).

55 Proportions, rather than absolute time, were used to adjust for different recording times per period.

1. Several times, the last heart rate file recorded prior to a computer breakdown was overwritten