2023 Nest Monitoring Report

Summary: Nest Box Recording began in 1986 on the Bagnor Estate when 17 small nest boxes were placed on trees in three spinneys in the Mount Hill Area. Since then monitoring has been expanded to include small nest boxes erected at Snelsmore Common (established 2001)  and Greenham Common (established 2002)

Location Reference: Ordinance Survey 1KM squares: SU4470, SU4571, SU4671, SU4964

Nest Boxes: (numbers have varied over the period 1986 to 2023) in 2023 they are as follows:

    Bagnor Estate 39 boxes - Snelsmore Common 64 boxes - Greenham Common 32 boxes

Visits: At least three visits made to every box after this those boxes that show little or no sign of occupation were dropped from the monitoring. The rest of the boxes were visited until nesting activity stopped:– failure at egg or pulli stage or the brood had flown from the nest. Between 17th April 2023 and 19th June 2023 four to eight visits to each of the occupied boxes were made until the last broods had fledged. Broods are ringed when young are around seven to ten days old. Blue and Great Tits and Nuthatches usually fledge around 19 days from hatching. Three final visits were made to all occupied boxes between the 17th and 19th June 2023 to check how many chicks had left the boxes (fledge).

Results:
Unoccupied               19 boxes
Unknown Species     19 boxes (no progress beyond nest building - 1 box taken over by Tree Bees)  
Blue Tit                      48 boxes, 474 young ringed, 466 fledge*
                                    *1 box, 8 ringed young probably predated at young stage (Woodpecker)
                                    2 boxes deserted at egg stage.
                                    1 box predated at egg stage (Squirrel or Woodpecker)
Coal Tit                      1 box,  9 young ringed, all fledged
Great Tit                    33 boxes, 248 young ringed, 246 fledged (2 young died before fledging)
                                    1 box didn’t progress beyond nest building stage.
                                    5 boxes deserted at egg stage.
Nuthatch                    2 boxes, 12 young ringed, all fledged.

Total Number of Nest Boxes 135 (Occupation 70%)

Brood Size (see chart below): To minimise the effect of variations in the number of boxes available, average brood size is used to give a more consistent indication of breeding trends over the 38 years. The chart below shows this for Blue Tit and Great Tit; other species occupation is too low or sporadic to use. Both species show some poor years over the period, Great Tit in particular shows variation. 2023 shows a steep drop from a very good Great Tit average brood size in 2022. Blue Tit also shows a slight drop from 2022. The trend lines use the moving average method as this shows 5 year period short term trend. The Great Tit trend line shows the first downward trend since the 2016 poor year for both species

Outcome: 2023 was a reasonable breeding year for both Blue and Great Tit, though for the latter five boxes deserting at egg stage is unusual, also some broods at young stage were  small – many eggs didn’t hatch. Only two boxes occupied by Nuthatch shows a lower utilisation of boxes but maybe there were more natural site available in recent time as a result of high wind damage to trees. Coal Tit rarely use nest boxes but are always a welcome find.  

Addendum: Nest Boxes were moniored but not ringed at the following known sites:

Bowdown Woods NR: 11 boxes, 2 unoccupied, Blue Tit occupied 5 boxes all fledged, Great Tit  occupied 3 boxes, 1 was predated at egg stage the others fledged, (IQ)

Sandleford Copse: 23 boxes were visited outcome unknown.

Peckmore Copse: 8+ boxes were visited outcome unknown.