Following on from our first Manx shearwater egg in our study plot nest boxes a week ago, we now have 4 eggs at the weekly check carried out yesterday (the same number we had by this date last year when we ended up with 11 eggs in total). Competition for prime nest locations and mates would seem to be heating up judging by the video footage captured in the past week. There are plenty of empty nest boxes and even more vacant natural burrows, well they might have rabbits in but that doesn't usually bother a Manxie. Despite this the fierce level of competition for nest box 56 has been interesting to observe.
The video below is taken from footage from one night (9th May) and the action all occurred within the space of 40 minutes but this has been going on every night since. It illustrates just how important good nest sites, and good mates, are to these male birds and they will defend it with their lives.
The rightful male from this box can be identified if you look closely as he has a black 'darvic' ring on one of his legs. This ring has been used to mount a tracking device on in others years but he is having a year off from being tracked in 2020. The other birds featured are all rival males; you can sex them from their high pitched calls. Manx shearwaters don't breed until they are 5 or 6 years old and, after first returning to the colony at age 2-3 years, they spend the next couple of seasons finding a suitable burrow and mate - and as you will see this can mean fighting for the privilege.
In the first scene 'our' bird is minding his own business in the burrow entrance when a rival male turns up and fighting breaks out. Look carefully and you will see the female poke her head out from the burrow and get involved. However when I slowed it down it actually looks like she ended up biting her mate!
In the second scene our birds are back in the nest box having a discussion. This attracts the attention of 2 rival males who themselves end up scrapping.
In the third scene 3 rivals males surround the entrance and begin a rumble, prompting our bird to emerge from the burrow and get stuck in too.
In the final show down what could be the rival male from the first scene has another go at our male culminating in an almighty brawl.
It would appear our bird saw off all comers that night as he is left alone at the battle scene but look at his head carefully and you will see he bears some hard fought scars of victory. This has been going on every night since and will have involved a huge amount of energy expelled by all birds. Our male in particular needs his strength if he is going to successfully raise a chick this year so it will be interesting to see if things settle once the female lays, assuming she does that is.
We will keep an eye on this nest box and bring you regular updates. In the meantime sit back and enjoy a scene that is played out in pitch darkness across Manx shearwater colonies on all islands that are lucky enough to host this remarkable bird