Hobby presence was mapped in a study plot of 41 km² in the central Netherlands centered around the town of Baarn in 2000-21. The region is densely populated, 31% of the area being occupied by towns and villages. The rest is covered by forest (37%), farmland (26%), heathland/sand dunes (3%) and open water (3%). At first, Hobbies were searched for in July, when chicks had just fledged and were noisy in the vicinity of the nest. Later on, the search for Hobbies started in April and involved a variety of methods, such as collecting observations collateral to nest searching for other raptors species, targeted nest searching, checking online observations from the public and follow-ups of hints from other raptorphiles and birdwatchers. Finding nests had priority, even considering the high costs in terms of time investment due to the silent and secretive behaviour of present-day Hobbies. Nine nesting territories of Hobbies were located over the years, each of which could be tracked for 8-21 years. The size of the nesting territory, here defined as the minimum convex polygon covering all nest sites contributed to a particular pair/territory, ranged between 51 and 245 ha, on average ± standard deviation 155 ± 70 ha. Most movements from one year to the next involved shifts to nests within 400 m of the one used the previous year (66 out of 84 nests), the longest movements of >1000 m being 1005 and 1180 m. Size of nesting territory increased with duration of the research period, probably coincident with large-scale felling of old stands of coniferous trees (especially douglas fir Pseudotsuga menziesii, the tree species in which nests of Hobbies were often recorded). The chance for Hobbies of running into habitat destruction within the breeding range increases the longer a nesting territory is occupied (especially now that commercial forestry and nature conservationists resort to large-scale felling of old stands in general and non-native tree species in particular), hence the larger nesting territories for pairs with high occupancy rates. Overall, fidelity to nesting territory was high, with even 8 out of 84 nests occupied twice (often, but not necessarily, in consecutive years). The length of occupancy also implies that specific areas must be attractive as nesting sites to different Hobbies, given the relatively high mortality rate (and hence high turnover) and the duration of the study period (extending beyond the maximum age of Hobbies).