Checking the Nest Boxes on Chorlton Ees and Ivy Green

Last year (2011) FoCM obtained a Council grant which allowed us to put up 20 bird boxes on the Chorlton Ees and Ivy Green Local Nature Reserve (see John Agar’s blog entry for March 2011). We put up 10 boxes on the Ivy Green side of Chorlton Brook and 10 on the Chorlton Ees side.

Last Sunday (15.01.2012) four of us: Dave Bishop, John Agar, John’s son Mark and Mark’s wife Julie set out to see if any of the boxes had been used over the previous nesting season, and to clean out those with old nests in. John brought his extensible, aluminium ladders and Mark his battery powered, electric screw-driver.

On the Ivy Green side of the brook we were dismayed to see that the first two boxes we checked were lying on the ground at the foot of their trees. At first we suspected vandalism but then we noted that the screws holding the boxes to the trees had snapped and the boxes themselves had left indentations in the bark of the trees. We had fixed the boxes to the trees too tightly and the expansion of the tree bark, in the course of the year, had exerted enough pressure to snap the screws! Nevertheless, both of these boxes contained nests. The very first nest had a single tiny egg in it which had obviously failed to hatch (see the rather blurred photograph above).

Of the next seven boxes, one had fallen - but all seven contained nests. As well as the old nest the third fallen box contained cherry stones with small holes gnawed in them. Such holed stones are a sign of mice – probably Wood Mice (Apodemus sylvaticus) – which had taken advantage of the fallen box for their own purposes.

We then moved across the brook to Chorlton Ees. It was a bit depressing to find that four of these boxes had gone missing. One had obviously been stolen because the thief had screwed the screw back into the tree (!) but there was no sign of the other three. We suspect that their screws had snapped and
the fallen boxes had been picked up and taken home to install in someone’s garden (at least, we hope that they’re being used). The remaining six boxes all had nests in them, although it looked as if one of the boxes had been abandoned part way through nest construction because wasps had taken up residence. You can see the remains of the wasps’ nest in the bottom photograph.

The nests we found seemed to be of two general types i.e. constructed almost entirely of moss or fibrous nests on platforms of grass stalks. The fibres used to construct the second type could have been synthetic, because some were green and others red. I suspect, though, that some of the fibres used
could have been dog hairs. Some of the old nests, mainly of the second type, were heavily contaminated with droppings and we suspect that birds had used them for shelter during bad weather.

All of the old nests were removed and discarded. The boxes then were cleaned out and returned to their trees, but this time the screws were not screwed in so tightly to allow for bark expansion.

John Agar’s conclusions on the significance of our findings are given below:

The likeliest species to have bred in our boxes are:

The Great Tit (Parus major) which is the largest and commonest European tit. This species breeds
in late April-June in deciduous woods, hedgerows, parks and increasingly in gardens. They nest in a hole of some kind, usually 3ft to 15ft above the ground, and often in tree stumps or walls, nest boxes and various other artificial sites such as drainpipes flower pots etc.

The Blue Tit (Parus caeruleus) which is the only native bird with blue and yellow plumage. Its breeding habits are similar to those of the Great Tit.

The Coal Tit (Parus ater) which is the smallest European tit being slightly smaller than the Blue Tit. This species breeds in coniferous woodlands but is increasing seen in deciduous woodlands and gardens.

Nests

All three species are remarkably similar in their choice of nesting material. Both sexes carry dry grass and
moss into the hole and lining it with hair, down or wool.

Eggs

All three species lay large clutches of eggs: Great Tits 8 -15, Blue Tits 9-12 and Coal Tits 7-12. There is
a remarkable similarity in the colouring i.e. white with red or reddish brown markings. The egg of the Great Tit is the largest but Coal Tit eggs are larger than those of the Blue Tit - even though it is the smaller bird.

In all three species the eggs are incubated by the female for between 14-18 days, during which time she is fed by the male bird. Hatchlings are fed by both parents and leave the nest after 2-3 weeks,

Remarkably all of our nest boxes had been occupied, although it`s not possible to know if all were successful. However, there was no evidence of dead nestlings in any of the boxes. Ideally the boxes
should have been cleaned out in the autumn when the nesting material would not have been so wet and degraded. I think it reasonable to assume that a good number of nestlings had fledged.

Given that the nesting material of the three species is so similar it is not possible say what number of each were present. It would require observation to be carried out when feeding was in progress. We’ll try to make these observations this year. I would expect that Great/Blue were in the majority with just two three pairs Coal Tits.

Finally, if anyone reading this has ‘rescued ‘any of the four missing boxes from Chorlton Ees, please, please, please make sure that you clean them out before the nesting season starts in a couple of months time!

Dave Bishop and John Agar, January 2012