Petrels are a family of seabirds known for covering large distances across open oceanic waters.

While we don’t know what species of petrels currently nest here on Rarotonga, historical records from 1895 show that one species – the Herald Petrel locally known as Kōputu – were providing local hunters with food and sport. The Herald Petrel today, can still be seen circling the peaks of our inland mountain areas in courtship behaviour before heading out to sea where they spend majority of their time. The remainder petrel species are nocturnal, and therefore less active during the day, and more active at night.

Since the pressures of hunting, our petrels now face new threats such as  an increase in predators –  rats, cats[AR1] [AS2]  and dogs. There are also invasive plants taking over preferred nesting habitat sites and marine threats such as climate change, pollution, overfishing and new potential threats like deep sea mining.

Today, little is known about the species of petrels present here on Rarotonga, including updated questions about whether these species are nesting here or on other islands in the Cook Islands. Because petrels inhabit inaccessible areas of Rarotonga such as the steep rugged inland mountain peaks, this makes it very challenging to monitor these seabird species.

Fortunately, today, monitoring equipment can greatly relieve some of these challenges as this equipment can be left in these hard to reach places, capturing clues on petrel activity at all hours of the day and night, for months at a time. These monitoring systems include acoustic recorders that record bird calls within a particular area. Different species of petrels and other seabirds have unique calls which the acoustic recorders can pick up, providing us with details as to what species are present here.

Another form of monitoring equipment are motion sensor cameras that turn on to capture activity if activated by movement. These motion sensor cameras can be useful to capture nesting behaviour and also clues on what animals may be predating on nesting petrel populations. 

Collecting this type of data is of value for both local knowledge and regional knowledge regarding the behaviour and distribution patterns of these migratory species. The presence of nesting species can also be used as an indicator of ecosystem health.  Identifying breeding populations could allow for co-management plans that not only protects nesting petrels but also the wider habitat in which they are found including watershed areas. Developing more research activity in this space can also contribute to local capacity building opportunities in the science realms of biology and ecology, using learning by doing surveying and monitoring techniques.

Recent observations here on Rarotonga have found that Herald petrels can still be seen swooping around our inland mountain peaks. This includes the recent extraordinary record, shared online, of a Herald petrel photographed attacking or approaching a drone at Te Rua Manga or the Needle. So they are still around!

However, whilst active Herald petrel signs are evident, there have also been recent discoveries of the real impacts predators today have on these ground nesting seabirds.

During a recent inland biodiversity survey, three dead petrels were found, all of which had been predated on by either cats or dogs. This recent find was also of great relevance as two of the dead petrels (identified as Herald petrels) appeared to be in an active nest site directly under a large tree fern. This, coupled with sightings on the same day of courting birds flying overhead, confirms that Herald petrels are still nesting in our inland mountain area, but are under clear threat.

Having identified that Herald petrels are still nesting on Rarotonga, this now leads to further awareness raising and discussions working closely with landowners, and how best to protect these migratory species whilst they choose to still nest here. This recent discovery also makes us wonder what other seabird species could also be nesting in the outer islands, particularly Mangaia and Atiu.