Encouraging double clutching slightly reduces productivity in bald eagles Haliaeetus leucocephalus in marshland sites in Florida, USA
Published source details
Wood P.B. & Collopy M.W. (1993) Effects of Egg Removal on Bald Eagle Productivity in Northern Florida. The Journal of Wildlife Management, 57, 1-9
Published source details Wood P.B. & Collopy M.W. (1993) Effects of Egg Removal on Bald Eagle Productivity in Northern Florida. The Journal of Wildlife Management, 57, 1-9
This study is summarised as evidence for the following.
Remove eggs from wild nests to increase reproductive outputAction Link
Remove eggs from wild nests to increase reproductive output
A replicated, controlled study in two marshland sites in Florida, USA, between 1985 and 1990 (Wood & Collopy 1993) found that 78% of 58 bald eagle Haliaeetus leucocephalus pairs that had their first clutch removed for hand-rearing (‘donor nests’) between 1985 and 1988 laid replacement clutches within two months. Replacement clutches were slightly smaller than first clutches (58 first clutches averaged 2.1 eggs/clutch vs. 1.8 eggs/clutch for 45 second clutches). In one study area, donor nests produced fewer fledglings than control pairs (1.0 fledgling/nest for 16 donor nests vs. 1.5 fledglings/nest for 39 controls), but this was not true in a second area (1.2 fledgling/nest for 26 donor nests vs. 1.1 fledglings/nest for 41 controls). Donor nests were more productive in the year before eggs were removed than the year after donation (approximately 1.3 fledglings/clutch for 32 pairs the year before donation vs. 0.85 fledglings/clutch for 34 pairs the year after). A demographic model suggested that a donor population would be very slightly smaller than a control population after 25 years. Timing of clutch removal did not affect the speed or probability of replacement clutches being laid.