This Week I Have Mainly...: Week Ending 7th July 2013

It’s been all smiles out here on Flat Holm this week after the weather has finally noticed that it’s supposed to be summer! This has made for far more interesting insect activity including the butterfly and the ladybirds that we survey weekly.

The Small Tortoiseshell butterfly population has soared and these were a common sighting across the island during this week’s survey, while the population of Small White and Green Veined White butterflies appear to have fallen.

A Small Tortoiseshell butterfly taking a break on a thistle

The number of casual sightings of other insects (we don’t have an official survey for them) has also increased with sightings such as this Blister Beetle below:

The "Blister Bug" can secrete a toxic chemical causing a nasty skin reaction including (yes you guessed it...) blistering

The Shelducks now appear to be leaving the island following the breeding season, with only 3 birds reported as being seen during the week’s survey. Across the country there have been reports of the Shelduck ducklings fledging their nests and taking to the water, but this unfortunately hasn’t been seen here on Flat Holm. Whether there were any ducklings that we missed or whether the season had been unsuccessful we will not know.

The main event of the week however was undisputedly the annual gull ringing weekend. You will have heard me mentioning the gull rings that we monitor here on the island in the previous blogs, and they enable us to study the migratory habits and lifespan of the birds. Since the last blog incidentally, we have recorded the sighting of a gull 2 years older than our previous best meaning that the oldest recorded gull on the island is now 18 years old!

Of course in order for us to be able to study these rings they must be applied to the gulls in the first place, and this is where this weekend’s event comes in. Every year a team of gull ringers comes over to the island, and with the help of us trainees we apply uniquely identifiable rings to 100 of the gull chicks. Each year the rings are a different colour and contain a different alpha-numeric code usually ending in F. This year the rings are green with white writing. This ring is placed on their left leg and a corresponding smaller silver metal ring is placed on their right leg.

The chicks have to be selected quite carefully, as it is in the interest of the project as a whole that they are likely to survive. This rules out the younger and smaller chicks as they are the most likely to be predated upon by the other gulls. However the oldest and most developed gulls are now able to fly, and as such are now nearly impossible to catch, making it a balance in judgement to select the right ones.

Vicky has selected a chick and is waiting to have the ID rings fitted

Although the effort took a lot longer than we had originally hoped we did manage to get all 100 rings onto a chick (and I don’t mean just one chick!), and they will now go on to be studied far and wide for years to come. Let’s just hope the Peregrines don’t feel the need to devour them all!

Me with the first chick that I helped to ring. Green and White 4TF. Maybe one day our paths will cross again?

*Side note - Speaking of the Peregrines, we are really excited to see that they have successfully bred on the cliff face this year and the young Falcon is now flying alongside it’s parents!*

While the bird ringers were on the island they also took the opportunity to conduct some mist netting to catch and ring some of the smaller species of bird that we have on the island. The nets are made of a fine dark material making them almost invisible when bright daylight isn’t present, and the birds become trapped in a shelf like layer of the net. This doesn’t harm the birds in any way and the nets are checked every 15-20 minutes to ensure that the birds do not remain trapped for long.

Setting up the mist nets

The smaller birds do not receive colour coded rings like the gulls, instead only receiving the small metal rings like the ones placed on the right legs of the gulls. After a few measurements and a weigh in the birds are then released and are on their way again.