Gentoo penguin research at the Falkland Islands 2012/13

Progress report October 2013

By:

Jonathan Handley

Supervisor: Dr Pierre Pistorius

Organisations:

Nelson Mandela Metropolitan University

Falklands Conservation

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Contents

Introduction _________________________________________________ 1

Research licence and ethics ______________________________________ 2

Methods ____________________________________________________ 3

Preliminary results _____________________________________________ 6

Public awareness ______________________________________________ 15

Toward the future _____________________________________________ 15

Acknowledgements ____________________________________________ 16

References ___________________________________________________ 17

Introduction

In context of global environmental change it is of great value to understand how marine top

predators use their habitat (Thiebot et al. 2011; Cottin et al. 2012). Knowledge of diet and foraging range

of marine top predators, where possible in relation to environmental variables, will be essential for

understanding their feeding ecology and foraging strategies (Barlow & Croxall 2002; Tancell et al. 2013).

This knowledge provides the link between the environment, lower trophic level and predators, and

quantifying top predator foraging behaviour is necessary to understand their roles in marine ecosystems

(Barlow & Croxall 2002; Boyd et al 2006). It establishes an understanding of critical habitat needs and will

serve for the protection of species and critical resources, and is central for the conservation and

management of marine top predators (Worm et al. 2003; Schofield et al. 2007; Kuhn et al. 2010; Costa et

al. 2012).

For penguins at the Falklands (Gentoo, Rockhopper, Magellanic), long term investigations using

stomach content analysis in the breeding season, revealed potential for interaction between these

species and commercial fisheries (Putz et al. 2001; Clausen & Putz 2002). This was predominantly for the

commercially caught Loligo gahi squid. However, in Gentoo penguins specifically these were of little or no

importance (Putz et al. 2001; Clausen & Putz 2002), although outside the breeding season they

accounted for over 50% of the diet at one site (Clausen & Putz 2003). The major outcome from these

studies was that Gentoos foraged on a diverse array of prey species, which largely reflected local prey

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abundance (Clausen et al. 2005) as observed elsewhere (Volkman et al. 1980; Adams & Klages 1989;

Coria et al. 2000; Libertelli et al. 2004; Lescroel et al. 2004). Furthermore, that fish of the genus

Patagonotothen (Rock cod) were an important prey item, most notably for colonies in the North (Cow

Bay, Seal Bay, Volunteer Beach) (Putz et al. 2001; Clausen & Putz 2002; Clausen et al. 2005). No recent

studies have focused on the diet of Gentoo penguins since the inclusion of Rock cod in 2006, a former

discard species, but now an important commercial resource (FIG 2011).

Gentoo penguins throughout their range are typically seen as inshore foragers (Croxall et al.

1988; Lescroel & Bost 2005; Takahashi et al. 2008), making them vulnerable to changes in local prey

density (Bevan et al. 2002). They typically do not forage further than 30km from the colony and rarely

exceed foraging trips of greater than 24 hours during the chick guard period (e.g. Adams & Wilson 1987;

Lescroel & Bost 2005; Kokubun et al. 2010, 2011). Presently, only at New Island on the west of the

Falkland Islands archipelago has the at sea distribution of Gentoo penguins been studied during the chick

guard period (Boersma et al. 2002; Masello et al. 2010), where both inshore foraging and trips under 24

hours were observed. The diet at New Island has been 30-38% crustacean by mass (Putz et al. 2001) and

when fish dominated by mass, Falkland herring (Sprattus fugensis, typically associated with coastal,

pelagic waters, typically schooling at or near the surface in waters of 0-70m depth (Whitehead et al.

1985)), accounted for 99% (Clausen et al. 2005). As inshore foragers, Gentoo penguins are bound to be

dependent on local marine resources (Lescroel & Bost 2005).

Currently only at New Island (Boersma et al. 2002; Masello et al. 2010) and during the winter at

Kidney Cove (Putz et al. 2003) has Gentoo penguin distribution been studied. Similarly to Saraux et al.

(2011), who recognise the value of monitoring the inshore foraging little penguin (Eudyptula minor) to

assess plasticity in these habitats, we recognise the need to investigate Gentoo foraging distribution

where diet is known to differ. This knowledge of foraging parameters, which have been used as proxies of

foraging effort (Lewis et al. 2001; Ryan et al. 2004; Pichegru et al. 2010), will form the first base line

estimates for foraging trips on which predictions can be made to determine future potential deleterious

effects, assisting in conservation and management of this species.

Research Licence and Ethics

This project was approved under licenses granted by the Falkland Islands Government,

Environmental Planning Department: R17/2011 & R13/2012. Animal ethics approval was granted by

Nelson Mandela Metropolitan University ethics committee (ALL-SCI-ZOO-014).

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Methods

Study sites

Field work for this project has been conducted at four sites (Figure 1) across the Falklands. These

include 1) Steeple Jason of the Jason Islands (Wildlife Conservation Society), 2) Cow Bay of Johnson

Harbour (Jan Cheeck), and 3) Bull Roads and Bull Point of North Arm (Steve Dixon). Sampling has

occurred during the incubation, chick guard, creche and post moult periods.

Figure 1: Study sites: 1.) Steeple Jason Island 2.) Cow Bay 3.) Bull Roads and Bull Point

Stomach Sampling

Birds were caught upon emerging from the sea on return to the colony (Trivelpiece et al., 1986;

Berrow et al., 1999) with a net attached to a long pole (Otley et al. 2005; Masello et al. 2010). To ensure

sampling of breeding individuals, only those birds with a vascularized brood patch were sampled

(Volkman et al., 1980). As Gentoos at Cow Bay appeared particularly skittish around their nests, as seen

elsewhere (Reilly & Kerle 1981), this minimised disturbance to birds. Stomach lavage followed Wilson

(1984). Birds were marked with a green temporary waterproof marker (Williams & Rothery, 1990;

Lescroel & Bost, 2005) on the breast feathers, and then released in the direction of the colony. This mark

1 2

3

4

lasts for approximately 10 days minimising the chance of repeat sampling and pseudoreplication. It also

allowed post identification of sampled birds to ensure normal behaviour was continuing. Sorting samples

followed necessary lab procedures.

Logger Deployments

Logger deployment includes that of all devices. These devices are Global Positioning System

Units (GPS), Time Depth Recorders (TDR’s) and Video Cameras.

Birds were monitored at nests and a single partner caught while the other tended to eggs or

chicks. The bird was then blindfolded, secured by the feet and head, and supported by one investigator

leaving the back exposed for unit deployment. A model was used for placement of the logger, ensuring

suitable, caudal, positioning of the logger to minimise the effects of drag by externally attached devices

(Bannasch et al. 1994). GPS loggers were then securely attached using overlapping layers of waterproof

adhesive TESA® tape (Beiersdorf, AG, GmbH, Hamburg, Germany). The tape is positioned non-stick side

against the body, underneath feathers, the unit above, and ends alternately pulled over, being secured by

cyanoacrylate glue (Loctite 401®). Secure fastening is essential for providing comfort and to avoid

interfering with foraging ability (Ryan et al. 2007). This method minimises the damage to feathers upon

retrieval (Wilson et al. 1997). Tape above the antennae position was removed to ensure optimal

functioning (Figure 2). Handling time was kept to a minimum, mostly below 15 minutes and always below

20 minutes (Masello et al. 2010). Birds were then released toward their nest to allow pair bonding

behaviour with partners. Birds were recaptured after a single foraging trip (Lescroel & Bost 2005),

therefore the following morning nests were checked at 0600h to assess if partners had departed. A

continual watch was maintained between 11h00 and 23h00 for birds with their unique markings. This

ensured that birds could be recaptured away from the colony minimising further disturbance. Retrieval of

the device took less than five minutes.

5

Figure 2: Deployment procedure for GPS units. A) Penguin is given unique marking after weighing. B)

Model of logger used as a placement guide. C) Strips of overlapping TESA® tape. D) Secure unit with tape

removed from antennae region.

Stable Isotopes

Material for stable isotope analysis was collected from all adult birds sampled either through

stomach content analysis or logger deployment. This involved clipping/plucking breast feathers. Feather

material was also collected from deceased chicks at study sites. Exemplar specimens to be used in

isotope mixing models were collected during the 2012 October Fisheries Department research cruise.

D C

A B

6

Preliminary results Figure 3 summarizes all data collected currently

Figure 3: Data collected during the course of the Gentoo research project over two seasons at SJ (Steeple

Jason), CB (Cow Bay), BR (Bull Roads), BP (Bull Point). Colours represent different sampling protocols.

Adult feathers were collected from all birds handled for stomach sampling or logger deployment. See key.

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Figure 3 Key:

I, G, C – Incubation, Guard and Creche period respectively

SS – Stomach Samples

TDR – Time Depth Recorder, note: 0 values for 2012/13 as these are included in the GPS

deployments

B – Humerus Bones from deceased penguins

Cam – Video Camera Deployments

GPS – GPS deployments, NB these are always with a TDR

CD – Deceased Chick Feathers

PMF – Feathers collected from adult Gentoo penguins during the post moult period

Stomach Sample Analysis

From the stomach sample data we have recognised 34 different prey items that Gentoo penguins

are feeding on (Table 2). Of these, we are able to distinguish 9 different crustaceans, 5 different

cephalopods, 11 different fish and 4 items classified as other. A full statistical investigation i nto diet

is currently underway. Preliminary results indicate that diet does vary across the islands and results

are similar to those published by Putz et al. (2002) who also investigated island wide differences.

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Table 2: Different prey types ingested by Gentoo penguins during the 2011/12 and 2012/13 chick

rearing periods at the Falkland Islands.

Species Common Name

Crustaceans Crustaceans

Campylonotus vagans Prawn

Euphasid spp. Krill

Munida gregaria Lobster krill

Munida subrugosa Lobster krill

Munida spp. Lobster krill

Munida spp. (juvenile) Juvenile lobster krill

Paguridae Hermit crab

Sphaeromatidae Isopod

Amphipoda 1 Benthic Amphipod

Amphipoda 2 Pelagic Amphipod

Themisto gaudichaudii NA

Cephalopods Cephalopods

Benthoctopod spp. Octopus

Cephalopoda (juvenile) Juvenile squid

Gonatus antarcticus Gonatus antarcticus

Lolgio gahi Loligo/Patagonian squid

Moroteuthis ingens Greater hooked squid

Semirossia patagonica Mickey mouse/Bobtail squid

Species Common Name

Fish Fish

Fish (juvenile) Juvenile fish

Agonopsis chiloensis Crocodile fish

Champsocephalus esox Icefish

Cottoperca gobio Frogmouth

Dissostichus eleginoides Patagonian toothfish

Harpagifer bispinis Magellanic spiny plunderfish

Macruronus magellanicus Whiptail hake/Hoki

Micromesistius australis Southern blue whiting

Patagonotothen spp. Rock cod

Perciformes Bony fish

Salilota australis Redcod

Sprattus fugensis Falkland herring

Thysanopsetta naresi Small flounder

Other Other

Bivalvia A Mussel

Bivalvia B Clam

Gastropoda Sea snail

Patellogastropoda Limpet

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We recognised six prey items to contribute most significantly to Gentoo penguin diet. These

included two squid: Loligo gahi, Moroteuthis ingens; three fish: Sprattus fugensis, Patagonotothen

spp. and juvenile fish; one crustacean: Munida spp. Owing to the fact that we identified fish species

using otoliths (ear bones) we were not always able to identify to species level. For the Munida spp.,

two species exist in the Falklands, Munida gregaria and Munida subrugosa. Over 99% of the

specimens that we identified were Munida gregaria, however owing to the fact that in some cases

we could not identify these too species we rather left identification to the genus level.

Looking at diet from the 2012/13 season, Gentoo penguins at Bull Point and Bull Roads have

a mixed diet consisting mostly of Munida spp., Patagonotothen spp. and Loligo gahi. At Cow Bay the

diet was dominated by two fish types, Patagonotothen spp. and Sprattus fugensis. At Steeple Jason

the diet was dominated solely by Sprattus fugensis (Figure 4)

Figure 4: The diet of Gentoo penguins across the Falkland Islands. SJ (Steeple Jason), CB (Cow Bay), BR

(Bull Roads), BP (Bull Point). I,G,C: Incubation, Guard and Creche period respectively.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

BP-G BP-C BR-G BR-C CB-G CB-C SJ-I SJ-G

%M

ass

Site and sampling period

Loligo gahi

Moroteuthis ingens

Sprattus fugensis

Patagonotothen Spp

Fish (Juvenile)

Munida Spp

Other

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GPS Tracking

Over the 2012/13 chick rearing period we made a total of 50 successful deployments at three sites

(Figure 4a,b,c) which included Steeple Jason, Cow Bay and Bull Roads. Eleven additional

deployments yielded insufficient data for analysis due to logger device error. This error occurred

mostly as GPS units could not obtain sufficient links to satellites or battery failure. At all three sites

birds tended to forage in a consistent direction. At Steeple Jason: staying within the confines of the

island, Cow Bay: heading out toward the open ocean, and at Bull Roads: staying in the bay.

Figure 4a: Gentoo penguin foraging tracks from Steeple Jason. (n = 9)

Figure 4b: Gentoo penguin foraging tracks from Cow Bay. (n = 20)

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Figure 4c: Gentoo penguin foraging tracks from Bull Roads. (n = 21)

Time Depth Recorder – TDR

The data obtained from these units includes that of pressure and temperature readings at an

extremely high fix rate of once per second. These units play a vital role in determining use of the

water column and vertical distribution of penguins once underwater, when GPS fixes cannot be

obtained. The pattern in the dive profile may be an indicator of foraging behaviour as well as a broad

indicator of food preference (Figure 5a,b).

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Figure 5a: Example of pelagic (V-shaped) dive which indicates feeding typically associated with

schooling species. These are typically seen at Steeple Jason where during the time of deployments

Gentoo penguins were feeding on the mid water, schooling, Sprattus fugensis.

Figure 5b: Example of flat bottom (U-shaped) dive which indicates benthic (bottom) feeding. These

are typically seen at Cow Bay where during the time of deployments Gentoo penguins were feeding

on the benthic Patagonotothen spp.

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Staple Isotope Samples

Material for stable isotope analysis is currently frozen and being stored for further processing. This

material will be utilized in stable isotope mixing models. The goal for these models will be to

determine if this method can be used as a simple, reliable, technique for long term monitoring of

diet trends. Although feathers only provide an indication of diet just prior to the moulting period (for

Gentoo penguins this occurs during March in the Falklands), they can be easily collected by

inexperienced individuals and stored safely for future analysis. Individuals could collect feathers

from around colonies during the moult period at regularly spaced intervals (would depend on the

penguin species), thus no need for handling animals. Feathers only need to be stored somewhere

dry. This material can then be stored for many years and could provide a reliable and easy method

for monitoring trends in diet.

Video Camera

This previous season we were able to deploy video cameras for the first time at Bull Roads.

Preliminary results support that diet in the Gentoo penguin is reflective of what is available in the

surrounding waters. Camera images from Bull Roads show an abundance of Munida spp. on the

seabed, an item that is well represented in the diet. This is contrary to Cow Bay where none of the

Munida spp. has been evident in any abundance, neither in the footage nor in the diet (Figure 6a,b) .

As video cameras were deployed with TDR devices, and will be deployed with GPS units in the

future, we aim to use this information to confirm the many inferences made from devices in the field

that are often difficult to assess in a non-natural environment. This information will increase our

understanding of the various inferences made, especially those that can be used toward

conservation and management of the species. For example: Understanding patterns in GPS signals

when birds are at sea by being able to see what the penguins are actually doing.

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Figure 6a: Cow Bay seabed is has no sign of abundant beds of Munida spp. and very little crustacean

in the diet, indicated by orange in the pie chart showing the diet from the 2012/13 season

Figure 6b: Bull Roads seabed has sign of abundant beds of Munida spp. and much larger crustacean

component in the diet, indicated by orange in the pie chart showing the diet from the 2012/13

season.

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Public awareness During the project we have participated in various functions. These have allowed promotion of the

parties involved and also provided unique educational opportunities for the public.

1. March 2012: Presentation to fisheries department – video camera use in research

2. July 2012: Presentation in South Africa at Nelson Mandela Metropolitan University – project

overview

3. September 2012: Project was awarded support by the Ruffords Small Grants Foundation

4. February 2013: FIGS School Day – Educational talk on fish and squid. Hands on practical

where children were able to dissect fish and squid.

5. March 2013: Presentation at Government House, Falkland Islands – project overview

6. August 2013: Videography on line by David Schutt

(http://www.falklandsconservation.com/penguin-watch).

7. September 2013: Presentation at 8th International Penguin Conference, Bristol, UK – video

camera use in research

Toward the future

The past two seasons work at the Falkland’s have been toward increasing our understanding of

Gentoo penguin foraging ecology. The work has yielded an abundance of information, some of

which has never been studied on Gentoo penguins. As the work formed part of an MSc thesis

originally, the abundance of data collected became far beyond the scope of an MSc. Due to the

exciting on-going research opportunities within the field of study, we are continuing with project

which will now be written up as a PhD thesis. This will ultimately lend to new and novel data being

gathered and analysed in the region. From the work to be completed there is strong possibility for

international publications, collaboration and conference attendance, all of which will provide further

opportunity to promote NMMU, Falklands Conservation as well as the Falkland Islands.

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Acknowledgements Numerous parties have made this project possible. We extended our greatest thanks to them for

their generous support through funding and equipment use.

Falklands Conservation

Nelson Mandela Metropolitan University

John Cheeck Trust

Ruffords Small Grants Foundation

Environmental Planning Department

Institut de recherche pour le développement

British Antarctic Survery

The support from landowners and land managers is ever grateful.

Steeple Jason – Wildlife Conservation Society

Johnsons Harbour – Jan Cheeck and Derek Petterson

North Arm – Steve Dixon

The Falkland Islands Fisheries Department played a critical role in the success of this project through

use of lab space, sample collection and all members involved in assisting with identification and

teaching of lab procedures. Particular thanks must go to Paul Brickle, Paul Brewin and Zhanna

Shcherbich all of whom played a lead role in teaching me and collecting samples.

To all the volunteers who provided valuable assistance in the field, the warmest gratitude is

extended to you. Particular thanks must go to Alistair Baylis, Sarah Crofts, Jacqui Bennet, Andrew

Stanworth and David Schutt who gave much time and provided valuable knowledge and advice.

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