Studies on aspects of the ecology of some hole nesting birds

The breeding success of four species of small, hole-nesting woodland birds, die Blue, Great and Coal Tits and Pied Flycatcher utilising nestboxes was examined. Three study areas in County Durham were selected, Hamsterley Forest (largely a plantation) and Backstone Bank and Horsleyhope Ravine, both of which are semi-namral oak woods. Some data were also collected in Kielder Forest, Northumberland. When die density of nestboxes was increased at a semi-natural woodland site Pied Flycatcher numbers increased but Blue Titi numbers did not change and die same effect was discovered in broadleaved sites in Hamsterley, however, no change in any bird species was found in die conifer areas. A significant negative relationship was found between die occupation percentage of all species and die altitude and a significant positive relationship between die coefficient of variation of die annual occupancy rate of all species and altitude. The same relationship was found for Blue Tit. Great and Coal Tit and Pied-Flycateher-did not show a significant relationship between occupancy and altitude, however, Coal Tit showed a significantly negative relationship between die coefficient of variation of die occupancy and altitude, whilst Great Tit and Pied Flycatcher did not show a significant relationship. A significant negative relationship between first egg date and clutch size was found for all four species. Blue Tits were found to have a significant negative relationship between first egg date and altitude. The differences m food availability shown by invertebrate sampling partially explained between year differences in productivity.