BTO Nest Box Challenge: Exploring a Blue Tit Nest

I came across the above tweet yesterday from the British Trust of Ornithology, reminding the public to clear their nest boxes out before 31st January. Now, please excuse my ignorance, but it never crossed my mind that boxes needed old nests removed; I had assumed up until now that we shouldn't interfere with them in case the birds were put off by our scent and that they would clean old sites out themselves. Of course, after reading some more information on the BTO website, and realising that my RSPB apex nestbox actually has a removable panel for the very purpose of cleaning, I got right to it.

The box I put up only last year was nested in by blue tits maybe a month or so after that which was great news for me, and I was fortunate enough to observe the parents flying in and out, firstly with nesting materials, then with all sorts of insects. You can read about my observations of the blue tit family, as well as the nesting nuthatches in the same tree, here and here.

According to Bird Protection Law, it is legal to clean out nest boxes between 1st August and 31st January and obviously it is important to make sure that the box is no longer occupied before you open it up. Even though I didn't actually see the blue tit chicks fledge from the box, I know they haven't occupied it for some months now so I was safe to go ahead with cleaning it out. I made sure I was wearing gloves and a bucket for the nest to go in, and I kept my face well away from it in case of any harmful mould that might have been growing.

This was my first time both seeing a nest up close and clearing it from a box so it was brilliant experience to have. My initial impression was of just how clean the nest was. I was being wary as I expected to see mites and fleas and for it to be quite unpleasant, particularly as it had been sitting in the box all through the damp, winter months. The reality was quite the opposite of my expectations; there was not one single mite, tick, flea or any other insect (apart from one tiny and slightly disgruntled spider) to be found. It had no smell, no mould and no pieces of eggshell. I knew the parents were frequently removing the faecal sacs as I had observed them doing it. It just goes to show what a fantastic job they did of maintaining a clean nest.

I wanted to get an idea of what materials they had used to form the nest, so I prised sections of it apart and had a good look through, without getting my face too close, to avoid breathing in anything harmful. The primary material was moss which had been used in great volume, creating a very densely-woven framework. There was definitely some solidity despite it being a soft structure. Interspersed between the moss were a variety of other components; leaves, straw, bits of animal hair (likely to be horse and cat since I put clumps of both out last year for them), and pieces of thread and feathers, including pheasant. There were also quite a lot ivy berries, some in big clumps at the bottom of the nest box. 

You can see a piece of thread clearly in the top left section, below the leaf.

A few materials, L-R: pheasant feather, moss, ivy berries, leaf.

Today, after clearing out the box yesterday afternoon, I observed a pair of great tits flitting around the branches surrounding the box site. One of them flew into the box and remained for some time while the second spent some time perching on the opening then flying to a nearby branch and back again. I didn't see the first bird exit the box while I was watching but it gave me real hope that, not only might the box be utilised for a second year, but it might be a different species. If they do choose to build a nest and lay eggs, it will be really interesting to see how the nest constructions differ, if at all. 

I have registered my nest box with the BTO Nest Box Challenge, which is a survey run to monitor nest sites all over the country. I am hoping that our nuthatches might nest once again in the knot hole a few meters above this box so I will have more than one nest to record observations from.