Adventures in the Azores: August to September 2020

This is a blog from our newest group member, one of my C-permit holders Alice Edney.

A long time ago (i.e. early 2020), in a land far far away (i.e. Wiltshire), I remember telling Simon that I would be disappearing for all of May to help monitor storm-petrels in the mid-Atlantic. Evidently, that did not happen. Fast-forward many months to the 12th August and there I was at Stansted airport about to board a plane to Terceira, Azores – to say I was excited would be an understatement.  

The purpose of the trip was to assist Hannah Hereward, a PhD student at Cardiff University, with data collection for her PhD. Hannah is researching ‘The conservation implications of climatic and tropic drivers of population change in the Monteiro’s Storm-petrel and its sister species’, and to do so requires travelling to a remote islet in the Azores Archipelago where both species breed. As a brief background, two seasonally distinct breeding populations of Hydrobates storm-petrels have been known in the Azores since 1996; however, they were only formally recognised as separate species in the late 2000s (Bolton et al. 2008). The breeding period (from first egg laid to last chick fledged) of the hot season species, Monteiro’s storm-petrel Hydrobates monteiroi, is May to early October, compared to October to mid-April for the cold season species, Madeiran storm-petrel Hydrobates castro (Bolton et al. 2008). Our fieldwork would observe the end of the Monteiro’s breeding season and start of the Madeiran’s, with the primary aim of recording the fledging of the Monteiro’s chicks.

With this in mind, we started each day by conducting a nest check. The storm-petrels breed in natural crevices across the islet but also utilise artificial nests, which were installed to offer additional breeding sites and enable easier and more consistent monitoring. As a minimum, we checked the artificial nests containing a chick each day, although we also checked every artificial and known natural nest at least twice during our stay. We measured chick wing length, tarsus length and weight, which provided information on chick growth, and also took measurements of any adults found in the nests. Watching the chicks develop and change from tiny balls of floof (not dissimilar to the contents of a hoover bag) into sleek adult-like birds was wonderful, and I think we all felt a bit like proud parents whenever one fledged. Some of the chicks still had a fair bit of growing to do when we left the islet, but hopefully they will fledge over the coming weeks.

Searching for storm-petrels in natural burrows (‘grubbing’) was a personal highlight. Despite sometimes having to delve into dense vegetation and contort into all kinds of strange positions, it was very rewarding when you did find a storm-petrel!

Alongside the nest checks, we deployed internal and external cameras on some of the nests to better understand the behaviours and interactions of the birds. Storm-petrels are nocturnal and so, to really get an insight into their breeding life, we needed to be able to watch them at night. The cameras were a great success and allowed us to observe innumerable behaviours, including chick preening, feeding, and fledging. On occasion we found a Monteiro’s chick outside its nest during the day and then a Madeiran adult inside the nest. Watching a small number of ‘our’ chicks be evicted by the Madeiran adults was difficult, but we could not interfere with the course of nature. Thankfully, one chick that was found injured on several occasions (and became a personal favourite, #107) went on to successfully fledge.

Monteiro’s Storm-petrel chick

As mentioned, working with nocturnal species means there is only so much data you can gather during the day, and indeed the best time to observe the storm-petrels was at night. As the sun started to set in the evening, the storm-petrels would return from sea. The air became alive with magical, fairy-like creatures twisting and turning, this way and that, and their mysterious songs filled the gloom. The night work was definitely some of my favourite whilst on the islet.

We successfully deployed and retrieved two GPS tags over the course of four nights and spent a further four nights mist-netting.

The GPS work has been neatly summarised in the following video https://twitter.com/HannahHereward/status/1301162264309968896, so I will spare the detail here; however, the severe lack of sleep was worth it for the tracks we obtained. Mist netting allowed a bit more sleep, as we were normally done by midnight as opposed to 6 am, although it was far more active. Running up and down to extract birds from the net every few minutes was a good workout, especially when a Cory’s Shearwater went in and needed removing ASAP. Having ringed a good number of Manx Shearwater on Skokholm Island last summer, I was familiar with handling this group of birds, but a Cory’s was quite something. A bit like a Manx Shearwater on steroids, they were larger, stronger and had a very powerful bill, which left a nice bruise upon contact. Like the storm-petrels, they too breed on the islet, and there was even one nesting in a burrow about a metre from my tent. At first, sleeping in the tent was somewhat difficult – the Cory’s crazy calls made it sound like we were under alien attack – but I soon got used to it, or else became too tired for it to keep me awake. Other seabird species on the islet included Common Tern and at least one Sooty Tern, and on our penultimate night we were lucky enough to hear, and then see, a Barolo’s Shearwater! This species breeds on the islet over winter, so it was amazing to have one return so early.

Cory’s Shearwater at the end of my tent.

Overall, I had an incredible experience in the Azores, and am very grateful to have been able to do fieldwork in such an uncertain time, and with two amazing people. Hannah and Max (the other field assistant) were great fun and together we managed to achieve a lot in a fairly short time period. Coming back to the UK has been unsurprisingly disheartening, but I am looking forward to returning to Wiltshire soon and resuming ringing with Simon and the team.

Back on the mainland with all the kit! L:R Alice, Max, Hannah.

More details about Hannah’s fieldwork can be found on her blog: https://musingsofamaroonedphdstudent.home.blog/.