Tawny Pipit (Anthus campestris) Science Article 2
The probability of predation was unrelated to outer nest diameter nor was there any relationship between internal diameter and the presence of unhatched eggs. Wall thickness and nest mass declined as the season progressed but there was no relationship between these variables and the mean environmental temperature during either seven or four days preceding the start of nest building. Clutch size did not correlate with outer nest diameter nor with nest mass but was positively related to nest volume.
Francisco SUAREZ, Manuel B. MORALES, Israel MINGUEZ and Jesus HERRANZ, Ardeola, 52(1), June 2005, 43-51