On the morning (between 08.00 hours and 09.15 hours E.S.T.) of the day following the last injection, each bird
was placed in a breeding cage containing a nest with two fresh eggs and a similarly injected and experienced,
but unfamiliar, mate. All of the birds' behaviour was recorded continuously, by hand, on sheets of paper divided
into 15-s blocks, for 1 hr immediately following introduction and again for 10 min, 24 hr later