Monday, 27 July 2015

A Kestrel visits Rockabill, and the tables are tern-ed.....

*Warning - this is nature at its most impressive and unforgiving. The pictures and story below mightn't be for everyone....*

We've had quite a few visitors to Rockabill in the past few weeks - people coming to help us with our work and research, or to carry out conservation research of their own, and some peopLe just for a quick visit!

As well as human visitors we've had some colourful invertebrates coming and going, in the shape of Hummingbird Hawk Moths and Small Tortoiseshell Butterflies. The air has been a bit cooler - a sign that autumn is on its way - and we've had some Whimbrel and Redshank passing by the island too, getting a headstart on moving to their wintering grounds. Both were duly added to our species list, along with another less-expected visitor - a young Kestrel!

Our first glimpse of the visiting Kestrel, minutes after arriving from the mainland (AP)
It wasn't long before it was on the move....but not back to Skerries.... (AP)

Kestrels are members of the falcon family, most often associated with farmland. Unfortunately like most farmland species, Kestrels are suffering from widespread agricultural intensification and are in decline both in Ireland and the UK. As agriculture intensifies across the country, complex habitats are 'simplified' and theres no suitable food or habitat left for the birds, mammals and invertebrates that formerly had our landscapes buzzing through the summer months. So with that in mind, I'm always delighted to see a Kestrel!

Kestrels have always been one of my favourite birds - along with Peregrines actually! But on Rockabill, both of these fantastic falcons have their sights set on the birds we're trying to conserve and protect! Now Kestrels and Peregrines have to eat too, and to be honest they're such excellent hunters and flyers that theres not a huge amount we can do about them anyway. It didn't take this young Kestrel long to become quite an efficient hunter on Rockabill, with plenty of chicks running round on the ground for the Kestrel to pounce on! By our count it was taking 1-2 chicks per day, usually taking its time to pluck its prey in-situ, despite the aggressive dissatisfaction of all of the adult Terns in the vicinity. Once it had removed the unimportant bits of little food value (the wings and legs) it would fly to the back of the Bill to eat its catch in peace.

Kestrel with a small chick as prey. (BB)
The Terns made plenty of noise, the Kestrel didn't really care! (BB)
This pattern continued over 4 or 5 days - the Kestrel would cause commotion from time to time, eventually get a chick and retreat back to the Bill after a few minutes of preparation/snacking. Silence again for a few hours, and then the Kestrel would move and cause the Terns to go mental again! It's worth noting that predation by Kestrels and Peregrines isn't a major worry - there are a lot more Terns here than a falcon could eat in an entire summer, and their visits are usually few and far between. Part of the reason seabirds live in these big colonies is to minimise the risk and impact of predators. On a few occasions we'd see the Terns all lifting off the ground and taking it in turns to swoop at something on the ground.....which turned out to be a rather confused and lost pigeon....but more often than not it was the Kestrel. This all continued until Wednesday evening......

As I was doing my nest rounds I noticed a sudden commotion as the Terns all noisily lifted off the ground and flew quickly out to sea - their usual tactic when a predator is in the air. I ran to take a closer look, but when I looked out to sea I realised a flock of hundreds of Terns were swooping and calling at a bird in the water. This is often what you see when a Gull has taken a chick, but this time it wasn't a Gull - it was the Kestrel!

The Terns had obviously landed a hit on the Kestrel, knocking it into the sea. Their continued bombardment of attacks left the Kestrel no opportunity to lift itself out of the water. As a result its feathers became more and more waterlogged, getting heavier and heavier. This continued for up to 20 minutes, the Kestrels struggles becoming more and more futile until it eventually drowned. The Terns were presented with an opportunity to get rid of their predator once and for all, and they seized it! No single tern is a match for a Kestrel, but hundreds of Terns are a different story entirely! On land the Kestrel can look after itself, but once it hit the water the tide turned, figuritively speaking.

The Terns knocked the Kestrel into the water and kept mobbing it (BB)

Once the Kestrel hit the water it was always going to be in trouble. (BB)

I'll be honest - I didn't like seeing this happen the Kestrel, despite the trouble its been causing the Terns. But that being said, it's nature! In nature you have predators that kill prey, but those predators aren't invincible either. This is how predators have evolved to be as fast, cunning and deadly as they are - the best survive and reproduce, and those that aren't on top of their game don't live that long. This was very much a once-off incident. Like the Kestrel won't have a significant impact on the Terns population, the loss of this one Kestrel won't make or break the local Kestrel population either - particularly at this time of year. It was certainly one of the most impressive wildlife moments I've ever witnessed, and I've seen a few!!

So that was the end of the Kestrel. I should point out that while hundreds of Terns were concerning themselves in this epic battle, a Peregrine flew in and took a Tern and flew away again! Talk about timing!

By the nest morning we were adjusting to life on Rockabill post-Kestrel, when we saw something on the Bill.....another juvenile Kestrel..............but this one left after a few hours thankfully!

An ex-Roseate Tern chick, thanks to Kestrel #2(AP)

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