Landau, 29th of January 2025.
Preliminary remark
Since 2021, researchers led by Dr Alejandro Simeone (1) have been conducting studies on the population, breeding success and foraging in Chile on behalf of Sphenisco. The studies are funded by the Species Conservation Foundation Zoo Karlsruhe, Dresden Zoo and the Association of Friends of Hagenbeck Zoo (see ‘Chile projects’ 4th of June 2021, 28th of November 2021, 18th of April 2022, 22nd of July 2022, 23rd of July 2023, 1st of January 2023, 9th of July 2023 and 23rd of November 2023 on these pages). After investigating foraging behaviour in the Choros Island area in 2022, the researchers investigated foraging behaviour in the Chachagua Island area in November and December 2024 and summarised the results as follows.
Summary
From 30th of November to 8th December 2024, breeding Humboldt penguins on the island of Cachagua, Chile, were studied using 15 GPS dive data loggers to investigate their range and diving behaviour. The work planned for this season on the island of Choros (Humboldt Penguin National Reserve) had to be postponed due to the lack of breeding birds.
The main work on Cachagua Island was carried out by Maximiliano Daigre and Ursula Ellenberg with the support of Paulina Arce and Alejandro Simeone on 30th November. Paulina and Alejandro focussed on counting nests as part of the general breeding census in Chile, contributing to data that will be presented in a separate report.
1. 15 breeding adult penguins (7 females, 8 males) were tagged with transponders (Trovan, 11 mm) and simultaneously equipped with GPS dive data loggers (AxyTrek, TechnoSmart, Italy, https://www.technosmart.eu/), which record the geographical position (via GPS receiver, recording every minute) and dive data (via pressure sensor, recording every second).
2. the penguin nests on Cachagua were mostly located in fragile burrows. The nests were selected for ease of access, i.e. without unduly disturbing penguins in neighbouring nests or risking the collapse of nests. All birds selected for the use of the loggers were in good condition and had healthy, one to four week old chicks.
3. all 15 birds were found after 1-7 days in good condition and with a similar body weight as before deployment. One female managed to remove the device without damaging her feathers. The remaining 14 devices were successfully recovered.
4. All the birds continued to care for their chicks after the mission. Due to the difficult weather conditions, which made it difficult to enter and leave the island, and the fragile nature of the breeding habitat, the island was not revisited. It is proposed to set up several surveillance cameras in the coming season to get a better overview of the overall breeding success on Cachagua Island.
5. The brevity of the stay on Cachagua did not allow the intervals between nest visits and the personalities of the penguins to be observed: Therefore, the use of high-resolution video cameras (PenguCam, New Zealand, https://pengu.cam/) was avoided this season.
6. The logger deployments yielded GPS and dive data from 14 birds (6 females, 8 males). The birds spent 592 hours at sea, spread over 47 individual foraging trips (27 day trips, 8 overnight trips, 12 short afternoon/evening trips). All trips lasted less than 24 hours (mean duration 14 hours, range 1.2 to 23.3 hours).
7. A total of 8,912 GPS positions (of which 5,380 were related to foraging) and 27,645 dives were recorded. Individual birds made 1-6 foraging trips per deployment. Distances averaged 41.3 km and ranged from 1 km (1.2 h evening foraging trip) to 84.8 km (foraging in the Aconcagua estuary).
8. The penguins showed a very coastal foraging behaviour, often foraging less than 5 km from the coast. Foraging dives were shallow, with an average depth of only 10.1 m (range 0.5 to 74.5 m).
9. All but one of the birds were foraging south of Cachagua Island, with most activity occurring within 20 km of Cachagua Island. Three birds swam past the community of Quintero, one of them as far as the community of Concón, where it foraged in the productive estuary of the Aconcagua River.
10. Interestingly, six birds foraged off Quintero (a heavily industrialised area). Three times the birds even came into the bay to forage amidst the industrial activities of the harbours.
Ursula Ellenberg (2) & Maximiliano Daigre Valdés (3)
notes
(1) The research group led by Dr Alejandro Simeone from the University Andrés Bello, Santiago consists of Dr Guillermo Luna from the University Católica del Norte, Coquimbo, Dr Thomas Mattern and Dr Ursula Ellenberg, both NZ Penguin Initiative, University of Otago
(2) Dr Ursula Ellenberg, Global Penguin Society, Tawaki Foundation / University of Otago, New Zealand
(3) Maximiliano Daigre Valdés, Humboldt Penguin Research Group, Chile
translated by Claudia Fawer
