Investigating the effects of gull harassment on southern right whale calves in Península Valdés: (II) report from September

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AMRU lab member Dr. Fredrik Christiansen reports from the second month of research in Península Valdés, Argentina, where he is investigating the effect of gull harassment on southern right whale body condition, in collaboration with local researchers Dr. Marcela Uhart (University of California Davis, USA) and Dr. Mariano Sironi (Univeridad Nacional de Còrdoba, Argentina), as well as Dr. Michael J. Moore (Woods Hole Oceanographic Institution, USA).

Windy conditions

After a great start in August, where good weather conditions allowed us to record over 1,000 body condition measurements, September proved to be a more challenging month. Strong winds prevented sampling on most days, and we only got a few really good days with perfect conditions. Still, we managed to make good use of these opportunities and obtained close to 500 measurements.

Calf growth

From the measured animals, we could already see how much the calves had grown since the start of the project. Research on southern right whales in Australia show that calves grows in length at an average rate of 3.2cm per day. When born, calves are about 5m in length, and by the time they depart on their southern migration back to their feeding grounds (about 3 months after being born), they are close to 8m in length. This rapid growth is only possible because of a large energy investment of the mother, who loses about 25% of her body volume over this time period.

Difference in body size of two southern right whale calves, the top one photographed in early August and the bottom one photographed in late September.

Increased frequency of gull lesions

If gull harassment causes mothers to spend energy avoiding attacks, then this could end up reducing the amount of milk provided to the calves. Alternatively, gull harassment could increase the energetic costs for calves, and/or disrupt nursing, which would negatively influence their body condition and potentially survival. From the aerial photographs collected in September, we could already see that most of the measured calves carried lesions from gull attacks. Research carried out by Marón and colleagues in 2015 showed that between 1970 and 2000, the proportion of mother and calf pairs with lesions on their backs increased from 2 to 99%.

(Left) Southern right whale calf in Península Valdés covered in lesions from gull attacks. (Right) Southern right whale calf getting harassed by kelp gull.

Whale camp

In September we had the opportunity to extend our research to Golfo San José, the Northern gulf of Península Valdés. We were fortunate to join Dr. Mariano Sironi and Dr. Vicky Rowntree in Camp 39 (aka ‘Whale camp’), where research on southern right whales have been conducted since Dr. Roger Payne built the camp in the 1970s. Since then, a large number of studies have been carried out in from this beautiful location, including research on behaviour, respiration patterns, gull attack frequency and genetics. Having the opportunity to do research from this location was hence a great honour. During our first visit, we were blessed with perfect weather conditions, and were able to photograph whales in crystal clear water. The water was so calm that not a single ripple was visible, and it looked like the whales were flying. The number of whales was again mind-blowing, and in a single photo we managed to capture 10 whales. An added bonus was the starry sky at night and a close encounter with a native Armadillo.

Golfo San José with its beautiful coast line and amazing wildlife, both on land and in the water.

Studying whale behaviour from the air

September also brought the addition of a new drone to our team, a DJI Mavic Pro. Although considerable smaller than the DJI Inspire 1 Pro used for body condition measurements, the Mavic Pro carries a camera capable of recording video in 4K. Together with a flight duration of 27min (the Inspire can only fly for 15min), it is the perfect drone for recording the behaviour of right whales from the air. Using the Mavic, we aim to record behaviour data from gull harassed whales in Península Valdés. We will compare this to behavioural data recorded from drones in Australia to find out how the behaviour of the whales differs between the two locations, and how this is influencing body condition.

A DJI Mavic Pro drone is being used to record behavioural data from southern right whale mother-calf pair in Península Valdés.

Presentation for whale watching operators

Península Valdés offers several locations where you can see whales form land, including El Doradillo. However there are also whalewatching companies taking people out to see whales from Puerto Pirámides. Every year researchers from Instituto de Conservación de Ballenas are invited to give a presentation about their research to the whalewatching community in Puerto Piramides. This year we were fortunate to join this event, led by Dr. Mariano Sironi, and present our body condition research in Península Valdés. It was a very nice evening, with loads of interesting presentations and discussions.

(Left) Dr. Mariano Sironi presenting the latest findings from ICB researchers to the whalewatching community of Puerto Pirámides. (Right) Dr. Fredrik Christiansen giving a presentation about the body condition works being carried out in Península Valdés in 2018.

Funding, permits and ethics

This study is funded by a research grant (Standard Grant) from the National Geographic Society (Grant number: NGS-379R-18). All research is being carried out under research permit from the Dirección de Fauna y Flora Silvestre and the Ministerio de Turismo, Provincia del Chubut, Argentina and an animal ethics permit from Murdoch University (O2819/16), Australia.

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