Late hatches are almost always a result of renesting after the failure of the first nest for various reasons. Second and even third nesting attempts in a breeding season are not uncommon in loons. Even loon chicks from first hatches will generally stay on their natal lakes until right before freeze-up, so there must be a benefit to stocking up fat reserves and working on wing muscles before their migration.
Although there have never been any studies of loon growth rates, late-hatching loons probably couldn't grow much faster than early hatchers. Therefore, loon chicks hatching later in the summer would be at a disadvantage, and less likely to survive.
The nesting instinct is bound to be stronger in some loons than in others, and some loons just don't know when to give up for the year. Even so, late loon hatches would not persist if all late loon chicks died before they bred. Nature weeds out these types of "mistakes." The reproductive gamble of late-nesting loons might pay off if freeze-up is especially late in the year.
Behaviour can be inherited, just like physical characteristics. If late chicks get away in time, even occasionally, they will pass this tendency for late renesting to subsequent generations.
- Harry Vogel
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Canadian Lakes Loon Survey
Bird Studies Canada
P.O. Box 160, Port Rowan,
Ontario, Canada N0E 1M0
Tel: 519-586-3531 Fax: 519-586-3532
Questions about the CLLS? Please contact Kathy Jones
Email: aqsurvey@bsc-eoc.org