The hobby is one of the very few birds

The hobby is one of the very few birds of prey capable of outflying swifts; perhaps at a speed approaching 100mph. The literature presents a full catalogue of victims, extending to escaped budgerigars which are taken regularly.

Its long narrow wings and relatively short tail help it to be very agile and aerobatic. The plumage is slate grey above, with dark longitudinal stripes below and red under-tail coverts. The chin and cheeks are white with a prominent moustachial stripe. Young birds are browner and lack the red under-tail coverts.

Length: 30-36cm; wingspan: 82-92cm

Status in UK
2,200 pairs, increasing; GREEN listed; summer visitor, normally arrives in the south of England in late April/early May

Population trends
Towards the end of the 19th century hobbies were confined to England south of a line from the Severn to the Humber. There were occasional records as far north as Yorkshire and even Perthshire.
During the first half of the 1900s their range contracted and the first Atlas of Breeding Birds of Britain and Ireland: 1968-1971 indicated about 100 pairs confined to heaths and downs in south-central England. Their absence from East Anglia was explained by the lack of crows and magpies, as they take over their old nests.

Source : http://www.hawkandowl.org/Species/DiurnalBirdsofPrey/Hobby