people in antarctica — how much do adélie penguins pygoscelis adeliae care?

8
Polar Biol (1991) 11:363-370 :~ Springer-Verlag 1991 People in Antarctica-how much do Ad/ lie Penguins Pygoscelis adeliae care? Rory P. Wilson, B. Culik, R. Danfeld and D. Adelung Institut ffir Meereskunde, Dfisternbrooker Weg 20, W-2300 Kiel 1, Federal Republic of Germany Received 23 January 1991; accepted 11 March 1991 Summary. In the course of physiological field studies, we opportunistically examined the effects of humans and aircraft on breeding Ad61ie Penguins Pygoscelis adeliae. Proximity to both aircraft and humans caused substantial increases in penguin heart rate even when no external stress was manifest. A solitary human at 20 m distance from commuting penguins on a well-used pathway caused the birds to deviate by 70 m. Birds at nests exposed to a single human fled much more readily when the brood consisted of large chicks (critical distance 6.1 m) rather than small chicks (critical distance 1.3 m) or eggs (critical distance 0.3 m). Aircraft caused birds to panic at distances greater than 1,000 m and 3 days exposure to a helicopter inhibited birds that had been foraging from returning to their nests, caused bird numbers in the colonies to decrease by 15% and produced an active nest mortality of 8%. Based on this data, we make recommendations to mini- mize stress on Ad61ie Penguin colonies exposed to man. Introduction There is public concern that man's presence in Antarctica might damage the ecosystem (e.g. Wfinschmann 1990). The Ad61ie Penguin Pygoscelis adeliae is an integral part of this system, being one of the most numerous penguins in the world with a population in excess of 5 million pairs (Woehler 1990). Ad61ie Penguin colonies only occur in the few areas of Antarctica where there is exposed rock at the coast. Such areas are also suitable for human settlement and consequently Ad61ie Penguins and humans often occur together. Long term studies indicate that the birds are decreasing at some of these sites (Wilson 1988; Wilson et al. 1990; Woehler et al., in press) which implies that somehow man compromises Ad61ie Penguin population growth rate. It is thus desirable that we understand what constitutes 'disturbance' to penguins so that measures can be taken to avoid it. O~print requests to." R.P. Wilson We examined the reaction of breeding Ad61ie Penguins to a single human and to different types of aircraft in an effort to be able to make recommendations about the minimum approach distance that does not lead to penguin disturbance. Such guidelines could be adopted by humans in Antarctica to reduce their impact of Ad61ie Penguin colonies. Disturbance to Ad61ie Penguins as a result of humans and aircraft has been observed at a number of stations of varying nationalities. It is thus invidious to single out the specific base where our studies were conducted. Accord- ingly, no reference in the text is made to locality or year of the study. Materials and methods During a recent field trip to Antarctica during a single austral summer to a site containing a breeding colony of ca 120,000 Ad61ie Penguins, we witnessed a number of events that caused disturbance to the birds. Most notable of these were aircraft flights in the vicinity. The penguins in this area are exposed to aircraft regularly (ca once every two weeks) during the summer so these birds might be expected to have become used to such disturbance. We were in the area to do approved physiological and ecological work on Adelie Penguins and thus were able to utilise opportunistically the systems that we had set up to try and document the effect of disturbance on the birds. Essentially three different techniques were used to quantify the reaction of Ad61ie Penguins to man-induced disturbance. Implants Between 12 and 13 December, four incubating Ad61ie Penguins were removed from their nests and the eggs protected. Heart beat fre- quency transmitters (here termed heart rate, HR) were then implan- ted into the birds' body cavities and detection electrodes placed adjacent to the heart (Culik et al. 1990a, b). We used halothane and xylocaine for anesthesia and each implantation operation lasted about 30 min. Birds received an intramuscular post-operative dose of 2 ml Binotal antibiotic before being replaced on their nests within 1 h of being removed. The birds were subsequently not handled until the end of the experimental period and continued breeding apparently normally at their four respective nests. When we left the site, 55 days later, one nest contained unhatched (but still incubated) eggs, one

Upload: rory-p-wilson

Post on 10-Jul-2016

214 views

Category:

Documents


2 download

TRANSCRIPT

Page 1: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

Polar Biol (1991) 11:363-370

:~ Springer-Verlag 1991

People in Antarctica-how much do Ad/ lie Penguins Pygoscelis adeliae care? Rory P. Wilson, B. Culik, R. Danfeld and D. Adelung

Institut ffir Meereskunde, Dfisternbrooker Weg 20, W-2300 Kiel 1, Federal Republic of Germany

Received 23 January 1991; accepted 11 March 1991

Summary. In the course of physiological field studies, we opportunist ically examined the effects of humans and aircraft on breeding Ad61ie Penguins Pygoscelis adeliae. Proximity to both aircraft and humans caused substantial increases in penguin heart rate even when no external stress was manifest. A solitary human at 20 m distance from commut ing penguins on a well-used pa thway caused the birds to deviate by 70 m. Birds at nests exposed to a single human fled much more readily when the b rood consisted of large chicks (critical distance 6.1 m) rather than small chicks (critical distance 1.3 m) or eggs (critical distance 0.3 m). Aircraft caused birds to panic at distances greater than 1,000 m and 3 days exposure to a helicopter inhibited birds that had been foraging from returning to their nests, caused bird numbers in the colonies to decrease by 15% and produced an active nest mortal i ty of 8%. Based on this data, we make recommendat ions to mini- mize stress on Ad61ie Penguin colonies exposed to man.

Introduction

There is public concern that man's presence in Antarctica might damage the ecosystem (e.g. Wfinschmann 1990). The Ad61ie Penguin Pygoscelis adeliae is an integral part of this system, being one of the most numerous penguins in the world with a populat ion in excess of 5 million pairs (Woehler 1990). Ad61ie Penguin colonies only occur in the few areas of Antarctica where there is exposed rock at the coast. Such areas are also suitable for human settlement and consequently Ad61ie Penguins and humans often occur together. Long term studies indicate that the birds are decreasing at some of these sites (Wilson 1988; Wilson et al. 1990; Woehler et al., in press) which implies that somehow man compromises Ad61ie Penguin populat ion growth rate. It is thus desirable that we understand what constitutes 'dis turbance ' to penguins so that measures can be taken to avoid it.

O~print requests to." R.P. Wilson

We examined the reaction of breeding Ad61ie Penguins to a single human and to different types of aircraft in an effort to be able to make recommendat ions about the min imum approach distance that does not lead to penguin disturbance. Such guidelines could be adopted by humans in Antarctica to reduce their impact of Ad61ie Penguin colonies.

Disturbance to Ad61ie Penguins as a result of humans and aircraft has been observed at a number of stations of varying nationalities. It is thus invidious to single out the specific base where our studies were conducted. Accord- ingly, no reference in the text is made to locality or year of the study.

Materials and methods

During a recent field trip to Antarctica during a single austral summer to a site containing a breeding colony of ca 120,000 Ad61ie Penguins, we witnessed a number of events that caused disturbance to the birds. Most notable of these were aircraft flights in the vicinity. The penguins in this area are exposed to aircraft regularly (ca once every two weeks) during the summer so these birds might be expected to have become used to such disturbance. We were in the area to do approved physiological and ecological work on Adelie Penguins and thus were able to utilise opportunistically the systems that we had set up to try and document the effect of disturbance on the birds. Essentially three different techniques were used to quantify the reaction of Ad61ie Penguins to man-induced disturbance.

Implants

Between 12 and 13 December, four incubating Ad61ie Penguins were removed from their nests and the eggs protected. Heart beat fre- quency transmitters (here termed heart rate, HR) were then implan- ted into the birds' body cavities and detection electrodes placed adjacent to the heart (Culik et al. 1990a, b). We used halothane and xylocaine for anesthesia and each implantation operation lasted about 30 min. Birds received an intramuscular post-operative dose of 2 ml Binotal antibiotic before being replaced on their nests within 1 h of being removed. The birds were subsequently not handled until the end of the experimental period and continued breeding apparently normally at their four respective nests. When we left the site, 55 days later, one nest contained unhatched (but still incubated) eggs, one

Page 2: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

364

nest contained one chick and two nests contained two chicks. Chick masses were not different to those of other chicks in the colony.

HR could be recorded from about 60m away by using a commercial radio. The signal was recorded on one channel of a stereo cassette player (Sony Professional quartz-locked "Walkman"). The other channel was used to record verbal descriptions of the birds' reactions during disturbance.

On 24 December, from a hide we recorded HR of two birds in their colony in response to the approach of a 'Super Puma' helicopter (Table 1). This was the first appearance of a helicopter since the visit of a 'MBB-BO 105' helicopter which had unloaded cargo 19 days earlier. On 7 January, we recorded the HR of a single bird within the colony being slowly approached by a human on foot prior to capture.

Video-recordings

Since Ad61ie Penguins are known to be disturbed by the presence of humans (Wilson et al. 1989a; Culik et al. 1990a), we used a video system, positioned for the duration of our stay on 8 December, to record penguin response to disturbance. The system was placed at a height of 2 m on a tripod and was equipped with a remote-controlled pan and tilt head and 12 • zoom telephoto objective. Observations were recorded on a Panasonic time lapse video recorder (AG 6010) with colour monitor 400 m away in a house out of sight of all surveyed areas.

Penguins moving between the colonies and the sea used well- defined pathways. On 12 December, we recorded the reactions of these commuting birds on one specific pathway to a single human (male, 190 cm tall) ambling and sitting in an area ca 20 m away. Undisturbed birds commuting between the sea and breeding colo- nies followed a specific path which led across a snow field and through a gulley (Fig. 1). We conducted fixed interval counts of the total number of birds passing through the gulley (68 m wide) and also noted the section of the gulley through which the birds passed; A through D, where A was closest to the source of disturbance, D furthest away, and B and C intermediate (Fig. 1). Counts were conducted every hour, on the hour, for exactly 10 min. We also recorded the reactions of the birds in response to approaches by a 'Twin Otter' airplane, 'Hercules' transport plane and 'Super Puma'

Fig. 1. Schematic diagram of the snow field over which penguins travelled to move between their colonies and the sea. Solid arrows show normal routes taken and the dotted arrow shows the route taken by birds following route E after being exposed to a human in area Ta. 1 and 2 mark the position of poles between which birds passed to be counted and A, B, C, and D indicate the different counting sectors (see text)

helicopter (Table 1). On 21 December, the Hercules flew at 240 km/h and 50 m altitude a straight line to a point 350 m away from the area surveyed by the camera and then continued its straight line course away from the site. On 23 December, the Super Puma helicopter flew the same course at ca 50 m altitude at a speed of ca 100 km/h and on 1 January, the Twin Otter flew the same trajectory at 200 km/h at 80 m altitude. Penguin activity was classified as (a) normal transit activity, (b) stop in response to disturbance, (c) move away from the source of disturbance and, (d) toboggan away from the disturbance. The reaction of the birds was scored as the percentage of all birds visible on the video screen engaged in a particular activity.

Between 23 and 28 December, which includes a three-day period (24 26 December) during which a Super Puma helicopter was extensively used at our study site, we used the video system to count the number of birds moving to and from the colonies on the pathway to the sea. Penguins were again counted hourly, over 10 rain, as they moved through the gulley (see earlier).During the same period, the camera was used to count, every 4 h, the number of adult birds in a specific study colony.

Direct observations

In order to quantify the effects of the helicopter on penguin colonies as a function of distance, we set up a transect running directly away from the proposed working area of the helicopter. Eleven colonies were surveyed, a colony being considered discrete when the nearest interbird distance exceeded 5 m. Approximately 2 h before the helicopter first flew, we counted the number of adults and active nests in each colony. We defined an 'active' nest as a nest where we judged that the associated adult was tending eggs or chicks. In some cases it was not possible to be sure of our opinion without disturbing the birds, something we wished to avoid. Such assessments are, however, considered reliable (Woehler and Burton, in press). The adult count was repeated immediately after the first flight, three times during subsequent helicopter operations and four times, spaced over 24 h after all helicopter activity had ceased. Ca 24 h after the last flight, we again counted all active nests in the colonies.

The reaction of nesting Adelie Penguins to the approach of a single human was also documented. A human (1.90m tall) ap- proached a nest at the periphery of a colony at a slow walk, The distance between human and penguin at which the nesting bird first took a step away from the intruder was noted. This process was repeated with a total of 35 different penguins tending nests at different stages of breeding, ranging from birds brooding eggs to birds guarding chicks in creches.

Results

Penguin reaction to humans

A single i m p l a n t e d bird, whose nest was 5 m f rom an o b s e r v a t i o n cabin, was a p p a r e n t l y ' a c c u s t o m e d ' to hu- m a n s since obse rve r s had been go ing to the cab in every 4 h to m o n i t o r H R in r e l a t ion to m e t e r e o l o g i c a l c o n d i t i o n s for 26 days. None - the - l e s s , on 7 J a n u a r y , the H R of this bird, which was s t a n d i n g by its nest in the co lony , c h a n g e d f rom 76 b p m to 135 b p m w h e n it was a p p r o a c h e d f rom 50 m to 4 m by a single h u m a n o v e r 4 min. T h e bird r eac ted (at 4 m) by wa lk ing a w a y to a d i s t ance of 8 m where , af ter ca 2 m i n H R was 1 2 6 b p m a l t h o u g h the b i rd a p p e a r e d u n c o n c e r n e d . F u r t h e r s low a p p r o a c h , o v e r 1 rain, to 3 m by the h u m a n caused an increase in H R to 140 bpm. S u b s e q u e n t c ap tu r e of the pengu in caused H R to rise to 287 bpm, which d r o p p e d to a s table 160 b p m one m i n u t e after the b i rd was pu t in a canvas h o l d i n g bag.

Page 3: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

Table 1. Technical characteristics of aircraft commonly used in logistic operations in Antarctica

Type Engine Power Wing/rotor Length Max mass no. (kw) span (m) (m) (kg)

MBB-BO 105 2 275 9.3 7.8 1,750 (Messerschmitt- B61kow-Blom, FRG)

Super Puma AS 332 2 955 15.0 18.8 6,400 (Aerospatiale/ Westland, France, UK)

DHC-6 Twin Otter 2 425 19.8 15.1 4,760 (De Haviland, Canada)

Lockheed C130 4 3,085 40.4 29.8 75,000 Hercules (Lockheed, USA)

365

Ad61ie Penguin reaction to man was highly dependent on whether the bird was guarding a nest and the stage of development of that nest. In general, birds tending nests left the area more readily when the young were more advanced (F=50.6, P<0.001; Fig. 2). This was par- ticularly obvious after the chicks began to cr6che.

In general, penguins commuting between the colonies and the sea began fleeing at much greater man/bird distances than birds tending nests, although we could not easily quantify this because commuting birds clearly influ- ence each other and it proved impossible to standardize man-bird distances.

Preceeding human approach, between 15h00 (11 Janu- ary) and 01h00 (12 January), 65% of all returning birds (Total= 1,552) passed through sector A, 7.5% through sector B, 20.6% through sector C and 6.3% through sector D (Fig. 3a). Intermittant 'human activity' between 15h00 and 20h00 (12 January) at ca 20 m from the main walkway and 50 m from the count area, caused returning birds to progressively deviate from their normal return route so that they made a 70 m detour before passing through the

gulley. Between 15h00 (12 January) and 01h00 (13 Janu- ary), 39.6% of all birds (Total= 1,989) passed through sector A, 32% through sector B, 22% through sector C and 6.4% through sector D (Fig. 3b). This is significantly different from the previous day (~2 ~___ 361, P < 0.0001). Even after the human was no longer present (at 20h00), birds continued using the new route until at least mid-night (Fig. 3b).

Penguin reaction to aircraft. In general, as aircraft ap- proached, penguins commuting between the sea and the colonies reacted by stopping any locomotory movement, then moving directly away, initially walking, then running and finally tobogganing. As the aircraft passed, this pro- cess was reversed (Fig. 4). Commuting Ad61ie Penguins responded to the various aircraft with different intensities. Their first reaction to the Twin Otter occurred when the aircraft was 1 km away. Most birds stopped all movement until the Twin Otter was at a distance of ca 500 m, when they began moving away; 10% tobogganed. By the time the aircraft had retreated to 600 m, all unnatural behavi-

z --

E

T

(.3 UJ er

0

E

,~ (8) / l

(7) T

E

JAN

Fig. 2. Mean approach distance necessary to elicit active movement away from a slowly approaching 1.90 m human by Ad61ie Penguins tending eggs or chicks

Page 4: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

366

% Number a

100

80

60

40

20

0 15 16 17 18 19 20 21 22 23 24 01

100

80-

60

40

20

o- 1,5 16 17 18 19 20 21 22 23 24

Time ( h o u r s ) 01

Fig. 3 a, b. Percentage of all penguins that traversed the counting area (see Fig. 2) that passed through the various sectors, A-D when (a) undisturbed and (b) subject to a single human 20 m to one side of the main pathway and 50 m from the counting area and closest to section A (Fig. 2)

our had ceased (Fig, 4). During the Hercules fly by, birds first reacted when the aircraft was 1.1 km away. By the time the aircraft had approached to 500 m, all penguins were moving away and when the plane was 350 m away 75% of all birds were tobogganing. Fifty percent of the penguins were still moving away when the plane had receeded to 2.3 km. Here, as in subsequent cases, we could not ascertain whether reduction in reaction was due to the disappearance of the stimulus or as a result of the post- stimulus time elapsed. Completely normal activity had resumed by the time the Hercules was 2.8 km away (Fig. 4). Penguins did not react to the Super Puma helicopter until it was closer than 600 m, but by the time it was 400 m away all birds were moving away. Reaction to the helicopter stopped equally quickly with 90% of all birds still moving away when the aircraft had flown to 1.25 km distance but virtually all fleeing had stopped by the time the helicopter was at 1.5 km. We were unable to quantify the percentage of birds tobogganing in response to the helicopter due to poor video resolution at this time.

Effect o f helicopter on HR. Implanted birds brooding chicks did not desert their nests even when approached by

100

~o

50

f

IO0 %

5O

0

50

O-

I ,I

I

TWIN OTTER

PUMA

~ _ _ ~ L TM Y

/ -1 8 6 4 4 6 s 1 2 3

DqSTANCE (kin} APPROACH RETREAT

Fig. 4. Reactions of commuting Ad61ie Penguins to approach and departure of various aircraft Twin Otter, Hercules transport plane, and Super Puma helicopter. Filled circles indicate the percentage of birds stopping movement in response to the aircraft, open circles indicate birds moving away from the aircraft and squares denote birds tobogganing away from the aircraft

a helicopter to 25 m. However, HR values rose from pre- helicopter mean resting values of 83.4 bpm (SD 6.7, N = 10 from 4 individuals) to a maximum value of 286 bpm (ANOVA, P<0.01), and were accompanied by head movements resembling 'Head Waving' (Ainley 1975; cf. 'Quiet Mutual Display', Sladen 1958). HR was inversely proportional to helicopter-penguin distance although HR decreased as a function of exposure time (Fig. 5). Penguins showed no change in HR when approached by the heli- copter to 200 m after an exposure time of 300 min al- though birds still reacted with less vigorous 'Head Waving'.

Eflect qlhelicopter on commuting birds. The first flight by the Super Puma helicopter was followed by 3 days of intensive helicopter flying in the area including instances when the aircraft flew to within 100 m of the area surveyed.

Page 5: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

1

V-D~J ou - ~uu z ~ v - . ~u ,a Juu -,~ou

Time (rain)

Fig. 5. Heart rate (bpm) in breeding Ad61ie Penguins as a function of distance (m) from, and duration (rain) of exposure to. a Super Puma helicopter

1 2 o ~ [

140

120 During this time, we saw no evidence of habituation by commuting penguins. Numbers of birds commuting be- ~oo tween the colonies and the sea (counted over 10rain 80 intervals every hour) dropped from a total of 3,125 (both 60 birds arriving and departing) on 23 December, before the helicopter arrived, to 2,223 (71%) and 1526 (49%) on 25 4o and 26 December, respectively, before rising to 3308 on 27 2 o

December after helicopter operations had ceased. The o number of birds successfully passing the counting point, and presumably reaching their nests, was directly related to local helicopter activity. The number of birds arriving or departing, which was highly variable during helicopter activity, rose when the helicopter paused, e.g. for re- fuelling, and sank when flight operations were re-started (Fig. 6). Helicopter activities appeared to discourage birds from returning to their nests. During periods of calm, waiting birds returned and changed with their partners which immediately departed to sea (unpublished data from video-camera surveyed colonies). Accordingly, dur- ,o ing helicopter operations, the number of birds departing in ~oo any 10 min interval was highly correlated with the number ~ 9o

z

arriving, e.g. for 26 December; No. departing = 10.1 + 1.2 X ~ 8o No. arriving (N=24, r2=0.74, F=62.5, P<0.001) al- ~ 70 though this was not the case in the absence of the helicopter, e.g. for 27 December, N=24 , r 2 =0.03, F=0.5, P > 0.05) (Fig. 6).

Number Returns

367

Effect of helicopter on colonies. After a single initial flight by the Super Puma helicopter along the colony transect line with aircraft-colony distance varying between 50 and 150 m, numbers of birds in the colonies dropped by a mean of 12% (Fig. 7). Subsequently, after ca 7 h of flight between the supply ship and a specific point, the percentage drop in bird numbers in colonies was related to the minimum distance (m) between helicopter and colony by % = (110.2 - 16.06 In dis tance)- 10 (r 2 =0.86) (Fig.8). At this point, the helicopter flight path became highly variable as goods were dropped at a number of widely differing points. Subsequently, we could not ascertain a clear relationship between percentage change in penguin numbers in colon- ies as a function of mean or minimum helicopter-colony distance. The video-surveyed colony showed substantial

0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3

D e p a r t u r e s

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Time (hours)

2e.~2 ~ 2z.~2 Fig. 6. Number of penguins returning to and leaving from their colonies as a function of time of day during undisturbed conditions on December 27 and helicopter operation on December 26. �9 26.12, Z 27.12

0

-10 z

o -20

H H

T T •

[

T I M E

Fig. 7. Numbers of adult Ad61ie Penguins in a video-surveyed colony and in l 1 human-counted colonies in relation to helicopter activity denoted by H

decreases in adults during helicopter operation (Fig. 7), but increased to pre-disturbance levels 24 h after the last helicopter flight. In the same way, eleven other colonies counted by observers on foot decreased by about 15% during helicopter operations but regained former numbers 24 h after the aircraft had stopped (Fig. 7).

Page 6: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

368

60

50

4O

o; 3o

u ~ 2o

0

- 2 0 . 0

24

%= (110.2 - 16.1 I n d i s t ) - l O r2=0.86

89

200 400 600

DIST TO HELICOPTER (rn)

Fig. 8. Percentage drop in the number of Ad61ie Penguins in colonies as a function of minimum colony-helicopter distance after ca 7 h of flights. Numbers associated with histogram bars denote initial colony size

During the three days of helicopter flights the total number of active nests in all 11 surveyed colonies dropped from 505 to 466, a mortality of 8%. No statement re- garding absolute chick mortality can be made since nest contents were not documented.

Discussion

Many authors consider Ad61ie Penguins essentially un- concerned by man (e.g. Oelke 1975). Careful research has shown that this is not the case (Culik et al. 1990a). Rather, it appears that there is no selective advantage for a flightless bird on land in the absence of experience of predators to show alarm reactions (Wilson et al. 1989a). Changes in HR in immobile birds are brought about by adrenaline and noradrenaline (Perry 1973) and are there- fore a useful measure of stress (Ball and Amlaner 1980; Kanwisher et al. 1978; Stout and Schwab 1980). Culik et al. (1990a) showed that in resting Ad61ie Penguins, HR may rise in implanted birds when solitary humans are as far away as 30 m. Resting rates of HR rise from 80 bpm to 127 bpm when birds are approached, and up to 310 bpm when birds are captured. These values compare well with the values we measured (76, 135 and 287, respectively) and demonstrate that the lack of visible reaction to man does not necessarily mean that the animals are not stressed (Boyd and Sladen 1971). It is possible that the radical changes in HR that we observed are only elicited in implanted birds and arise as a result of stress in animals that have been captured and operated on. In cases such as this no controls can be set up. However, in all other

respects, implanted birds behaved in an identical manner to non-implanted birds. We believe, therefore, that ob- served changes in HR are likely to be typical of Ad61ie Penguins.

Part of the diff• in assessing man-induced disturb- ance stems from different critical distances (the minimum distance between the source of disturbance and the birds at which stress is first noticed by us) according to the breeding status and current activity of the bird in question. Although birds with larger chicks appear to be more stressed by the approach of a man than birds with small chicks or eggs, we suggest that the physiological stress is the same in both cases. Rather, the likelihood that a bird will actually flee is presumably inversely related to the chances of survival of the brood if left alone. Exposed small chicks and eggs are predated almost immediately by Skuas Catharacta maccormicki or C. skua while chicks at cr~c- hing age are less likely to be attacked (personal observa- tion). Since commuting birds have no brood to protect, they are particularly likely to flee when disturbed. This explains why observers sitting inadvertently near major walkways can invoke major deviations in the walkway routes, which may be maintained for hours after the source of disturbance has gone. In our case, the single observer invoking an extra 70 m travel for returning birds caused an estimated 11,934 birds to deviate during 10 h, amounting to an extra 835 penguin kilometres walked.

Aircraft are clearly highly stressful to Ad61ie Penguins (Sladen and LeResche 1970; Thompson 1977) and even short exposure to this sort of stimulus causes massive panic at distances of up to 1 km. Helicopters cause a proportion of brooding and incubating penguins to leave their nests thereby exposing eggs and chicks to depre- dation by skuas (Thompson 1977; Ainley et al. 1983). Although brooding penguins do seem to show habituation in HR over time, helicopter operations appear to dis- courage birds from returning to feed their chicks and we found no evidence that returning birds became more used to the aircraft during 3 days helicopter exposure. Similarly, Olsson and Gabrielson (1990) report high levels of distur- bance of Brfinnich's Guillemots (Uria lomvia) to heli- copters with no indication of habituation.

The 8% 'active nest' mortality seems high, however, it is difficult to convert this figure into conventional mor- tality data. For example, some of the nest desertions were presumably from birds with addled or late-laid eggs, nests that would not have been successful, irrespective of aircraft activity. Penguins tending such nests are more likely to desert than congeners tending 'successful' nests (personal observation). It is, however, clear that aircraft activity does cause some chick mortality, not being uniquely limited to inducing changes in bird physiology or activity rhythms. Mortality is probably due to nest desertion by brooding adults leading to predation by Skuas. Since the likelihood that Ad61ie Penguins flee is dependent on brood age, mortality resulting from aircraft operations is likely to vary according to the stage of breeding when penguins are exposed to aircraft. Furthermore, since cr6ching chicks flee when exposed to aircraft (Culik et al. 1990a) and brooded chicks cannot, disturbance would be minimized if aircraft

Page 7: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

369

were operated before the cr6ching period, and preferably, if it cannot be avoided altogether, when birds are in the middle of incubation: Birds in breeding pairs alternate long incubation shifts (Davis 1982) so there is very little commut ing activity at this time and fewer birds in the colonies overall. Finally, Wilson et al. (1989b) showed that breeding Ad61ie Penguins have a diurnal activity rhythm where most birds leave the colonies to forage between 4h00 and 8h00 and return later that day between 18h00 and 23h00. This pattern is most obvious when daily light levels are most dynamic. Thus, numbers of birds in the colonies are lowest at mid-day. The number of individuals stressed by aircraft could, therefore, be reduced by limiting flight operat ions to the hours a round mid-day.

Unfortunately, it is extremely difficult to conduct scientifically sound disturbance experiments because the intensity of the invoked reaction may be dependent on many factors which are difficult to control. We observed that reaction intensity was dependent on (a) bird activity preceding disturbance, (b) the reaction of surrounding birds, (c) the speed of approach of the source of distur- bance (cf. Ball and Amlaner 1980), (d) previous exposure to disturbance (cf. Stout and Schwab 1980; Olsson and Gabrielson 1990 and references therein) and, (e) breeding status. In addition, intensity of reaction may be affected by (a) time of day, (b) weather, (c) the size and colouring of the stimulus (cf. Wilson et al. 1990), (d) the age of the bird and, (e) the size of the group around the individual to be tested. Despite these complications, there are a number of recom- mendations that can be made that would minimize stress on Ad61ie Penguin colonies exposed to man.

(1) Any work conducted during the austral summer that is likely to disturb penguins should be carried out after chicks have fledged, otherwise when birds are incub- ating and have been incubating for at least 10 days. The latter period generally occurs at the end of November; chicks fledge in February (Ainley et al. 1983).

(2) Potentially disturbing work should be carried out a round mid-day

(3) Nesting birds should not be approached by hu- mans on foot closer than 30 m unless absolutely necessary.

(4) Penguins moving on routes between the colony and the sea should not be approached by humans on foot closer than 100 m unless absolutely necessary.

(5) Aircraft should use the same flight path for serial drops and Super Puma helicopters should not approach a colony closer than 1,000 m horizontally and 200 m verti- cally.

(6) Many more Specially Protected Areas should be established in the Antarctic under provision of the Antarc- tic Treaty.

(7) Provisions in the Antarctic Treaty should be made to prohibit establishment of bases within I km of penguin colonies.

Acknowledoements. This study was funded by the Deutsche For- schungsgemeinschaft. D. Ainley, N. Bonner and R. Abrams provided many helpful suggestions for improving the manuscript. We thank A. Hilner and M. Jimenes Lopes for transcribing HR data.

References

Ainley DG (1975) Displays in Ad61ie Penguins; a reinterpretation. In: Stonehouse B (ed) The biology of penguins. Macmillan Press, London (UK). pp 504-534

Ainley DG, LeResche RE, Sladen WJL (1983) Breeding Biology of the Ad+lie Penguin. University of California Press, Berkeley

Ball N J, Amlaner CJ (1980) Changing heart rates of Herring gulls when approached by humans. In: Amlaner C J, MacDonald DW (eds) A handbook on biotelemetry and radiotracking. Pergamon Press, Oxford (UK), pp 589-594

Boyd JC, Sladen WJL (1971) Telemetry studies of the internal body temperatures of Ad61ie and Emperor penguins at Cape Crozier, Ross Island, Antarctica. Auk 88:366 380

Culik B, Adelung D, Heise M, Wilson RP, Coria NR, Spairani HJ (1990a) In situ heart rate and activity of incubating Ad61ie Penguins (Pygoscelis adelie). Polar Biol 9:365 370

Culik B, Adelung D, Woakes AJ (1990b) Effects of disturbance on the heart rate and behaviour of Adelie Penguins (Py.qoscelis adeliae) during the breeding season. In: Kerry KR, Hempel G (eds) Antarctic ecosystems. Ecological change and conservation. Springer, Berlin Heidelberg New York, pp 177 182

Davis LS (1982) Timing of nest relief and its effect on breeding success in Ad61ie Penguins (P)u adeliae). Condor 84:178 183

Kanwisher JW, Williams TC, Teal JM, Lawson KO (1978) Radiotel- emetry of heart rates from free-ranging gulls. Auk 95:288 293

Oelke H (1975) Breeding behaviour and success in a colony of Ad61ie Penguins at Cape Crozier, Antarctica. In: Stonehouse B (ed) The biology of penguins. Macmillan Press, London, Basingstoke (UK) pp 363 396

Olsson O, Gabrielson GW (1990) Effects of helicopters on a large and remote colony of Brfinnich's Guillemots (Uria Iomvia) in Svalbard. Nor Polarinst Rappser 64:1 36

Perry G (1973) Can the physiologist measure stress? New Sci 60:175 177

Sladen WJL (1958) The pygoscelid penguins, parts 1 and 2. Sci Rep Falkld lsl Depend Surv 17:l 97

Sladen WJL, LeResche RE 0970) New and developing techniques in Antarctic ornithology. In: Holdgate WM (ed) Antarctic ecology, vol 1. Academic Press, London, pp 585 596

Stout JF, Schwab ER (1980) Telemetry of heart rate as a measure of the effectiveness of dispersal inducing stimuli in seagulls. In: Amlaner C J, MacDonald DW (Eds) A handbook on biotelemetry and radiotracking, Pergamon Press, Oxford (UK), pp 603 610

Thompson RB (1977) Effects of human disturbance on an Addlie Penguin rookery and measures of control. In: Llano GA (ed) Adaptations within Antarctic ecosystems. Smithsonian Inst, Washington DC, pp 1177 1180

Wilson GJ (1983) Distribution and abundance of Antarctic and sub- Antarctic penguins: a synthesis of current knowledge. BIOMASS Sci Set 4:1 46

Wilson GJ (1988) Fluctuation in the Adelie Penguin (Py,qoscelis adeliae) population at Cape Bird. Abstract in 1st lnt Conf on Penguins, Dunedin, New Zealand

Wilson GJ, Taylor RH, Barton KJ (1990) The impact of Man on Adelie Penguins at Cape Hallen, Antarctica. In: Kerry KR, Hempel G (eds) Antarctic ecosystems. Ecological change and conservation. Springer, Berlin, Heidelberg New York pp 183 190

Wilson RP, Coria NR, Spairani H J, Adelung D, Culik B (1989a) Human-induced behaviour in Adelie Penguins Pygoscelis adeliae. Polar Biol 10:77 80

Wilson RP, Culik B, Coria NR, Adelung D, Spairani HJ (1989b) Foraging rhythms in Ad61ie Penguins (Pyyoscelis adeliae) at Hope Bay, Antarctica; determination and control. Polar Biol 10:161 165

Wilson RP, Spairani H J, Coria NR, Culik B, Adelung D (1990) Packages for attachment to seabirds: what color do Ad61ie Penguins dislike least? J Wildl Manage 54:447 451

Page 8: People in Antarctica — how much do Adélie Penguins Pygoscelis adeliae care?

370

Woehler EJ (1990) The distribution and abundance of Antarctic and Subantarctic penguins. SCAR Bird Biol Subcommitteee/ BIOMASS Sci Set

Woehler E J, Burton HR (in press) Increases in the breeding popula- tion of Ad61ie Penguins (Pygoscelis adeliae) at Whitney Point, Wilkes Land, Antarctica, 1959/60 to 1989/90. Mar Ornitol

Woehler EJ, Slip D J, Robertson LM, Fullagar P J, Burton HR (in press) The distribution, abundance and status of Ad~lie Penguins Pygoscelis adeliae in the Windmill Islands, Wilkes Land, Ant- arctica. Mar Ornitol

Wfinschman A (1990) World Wildlife Fund, Germany. S~iddeutsche Zeitung 1 September 1990, p 11