Satellite-tagged Pallid Harrier died in southern Morocco

A Pallid Harrier (Circus macrourus) named ‘Selja’ satellite-tracked from Finland died in southern Morocco last January. The cause of death is not electrocution as was feared initially.

Selja was fitted with a satellite transmitter in central Finland in June 2018 as part of the research on Pallid Harrier carried out by Ari-Pekka Auvinen for the Finnish Natural History Museum (LUOMUS).

She arrived to Guelmim in southern Morocco on 13 November 2018. She would spend here the whole winter until 21 March 2019 when she started her northward migration. She became the first Pallid Harrier to winter in Morocco.

Once arrived to Finland, instead of nesting in the same area as in 2018, she chooses to settle in the north-west near the Swedish border where she paired with a new male. The pair successfully raised their chicks. Dutch harrier specialist Ben Koks and journalist Elvira Werkman visited her breeding area and took the following photos (Selja, her male and the ringing of one of her chicks by Ari-Pekka Auvinen). More about their visit on this link (in Dutch): Op zoek naar Selja.

Helaas, #pallidharrier Selja is dood. Zag haar afgelopen zomer in #Finland met @elvirawerkman . Onderzoeker Ari-Pekka Auvinen ringde haar jong, Selja kreeg in 2018 een zender van m. Vogelaars zoeken in Zuid-Marokko naar de resten. @MoroccanBirds @luomus https://t.co/DeoJMSZkx9 pic.twitter.com/3Idi47uRod

— Ben Koks (@demanopdedijk) January 14, 2020

Wintering in Morocco for the second year

This season, Selja arrived at the same wintering ground in the Guelmim region in early December 2019. After a month or so, Ari-Pekka Auvinen informed us that she most likely died on 9 January 2020. The cause of death was not known at the time, but we strongly suspected electrocution was the likely cause. The problem of bird electrocution is so serious in this region that we talked about it even when nothing actually happened to Selja in her first winter.

To find out what happened and try to retrieve the transmitter, I contacted our friend and colleague Ali Irizi from the Association of Friends of Raptors (ASARA). Fortunately, he agreed to volunteer and headed south to Guelmim on 6 February 2020.

His observations suggest that the cause of Selja’s death was not electrocution (e.g. no visible injuries on feet or wings). She was more likely attacked by a predator, with the likely ‘culprits’ include mammals such as African Golden Wolf (Canis anthus). Or maybe, it was killed first by a bird of prey such as Pharaoh Eagle Owl (Bubo ascalaphus) and finished off by a mammal later (note the partially crashed head). The photos below are reminiscent of those of an English Osprey who was also predated by Pharaoh Eagle Owl or a mammal in the same general region some years ago (see below the first photo in that link).

Update: here’s Ari-Pekka Auvinen’s comment regarding the cause of death:

“Looking at the remains of Selja I see the bones pretty much intact. To me it looks like she has been eaten by an avian predator, not a mammal. A large mammal would have bitten her bones and probably taken some parts of the body apart. The crushed skull could also be the doings of a Pharaoh eagle-owl or similar since I think bird predators also like to eat the brains of the prey (often first). I have seen this with owls many times as I take care of injured birds”.

Sadly for Ari-Pekka and his research, Selja was not the only Pallid Harrier to die this year. Another bird named ‘Hippu’ also died. Unlike Selja, Hippu used the easterly route through Russian, Greece and Libya to reach the Sahel, see her full track here.

Regarding Hippu, Ari-Pekka said in email:

“I have been pretty disheartened by the deaths of both of “my” pallid harriers. The other one, Hippu, was perhaps shot in northern Nigeria. She stayed for a long time in a remote spot in Niger, but then started to move southwards and eventually arrived at the Bagauda Reservoir on January 12. She was hunting there until she suddenly became cold and motionless. The last fix from her transmitter was from inside a house in a near-by village. I have heard nothing from her since”. 

Some good luck is needed when searching transmitters

Here are some anecdotes which I think we should keep in mind when we try to find a dead bird carrying a satellite transmitter. Children can stumble upon the birds and destroy their transmitters out of curiosity.

In the case of Selja, despite her carcass – with her transmitter – was laying there on the ground for almost a month, Ali Irizi found everything intact. It’s a different story in more density areas in the north where children can be found everywhere. A Moroccan colleague, studying another raptor species, has lost a few satellite transmitters because the children arrived before him (and that’s within a short period after the birds’ death). So luck is very important in some cases like these (more details when he publishes his results).

But it’s not always like this. A small girl found an electrocuted Spanish Imperial Eagle (Aquila adalberti) in the Rif region last year, and guess what, she informed her father about her find. When our friend Mohamed El Andaloussi from ‘AZIR Association’ went there later, he found the transmitter safely stored in the family’s house.

Adults can also find the transmitters first, and the diplomacy is needed in these cases to convince them to cooperate (This is exactly what happened with the man who found this satellite-tracked White Stork).