Figure 3. Average timing of nesting events for great tits (GT) and blue tits (BT) at Cambridge University Botanical Gardens (CUBG; green), Cow Lane Nature Reserve (CL; blue) and Brampton Wood Nature Reserve (BW; red).

Symbols denote median dates for first egg (E), clutch completion (C; and earliest potential start of incubation) and hatching (H) and the bars show the interquartile range for the 9 year average 2003-2011 (hatched, upper), and 2012 only (solid, lower).