The most recent assessment of the British population is 7,000 pairs (Baillie et al, Bird Trends 2011, BTO Research Report 609). This may be compared to the previous best estimate of 8,700 pairs (Baker et al,  British Birds 99:25-44).
The BTO Common Bird Census & Breeding Bird Survey have shown a 33% decline in England over the decade 2000 to 2009 which itself is part of a longer term downward trend evident from a population peak in the mid-1980’s. The State of UK Birds (Eaton et al, 2011) indicated that the national population had fallen 40% between 1970 and 2009.
Raptor workers are encouraged to submit more reports via the Nest Record Scheme to enable population trends to be better understood.
Agricultural intensification presents the greatest threat to Little Owl populations. Year on year severe winters also adversely affects numbers.
Little Owls prefer lowland, open arable habitat with old trees, mature hedgerows or farm out-buildings for nesting. The species remains quite common in the NERF recording area at lower elevations. It is recognised that the focus of attention for raptor fieldworkers is towards species in upland areas and as such Little Owls are generally under-recorded. With the exception of Manchester RG, no local RSG monitors Little Owls on a dedicated basis although several groups acknowledged that more ought to be done if resources allowed. A study undertaken by Calderdale RSG in 2011 to collate all records in their area is commendable and shows how finite resources can be used more effectively to extend our knowledge for this and perhaps other poorly monitored species.
Member groups have commented on early signs of possible population decline so clearly this is a species that merits closer study.