SHORT COMMUNICATIONS 
391 
First egg 
’ 
r 
' 1 
Cavity 
#1 
Nestling 
Fledgling 
Hatch 
Fledge 
Male stops feeding 
fledglings 
Ma!e stops Femak 
! 
^ * 
Cavity 
Laying 
Incubating 
#2 
— — P* ^ 
HG. 1. Timeline illustrating important events during nesting at the two cavities of a Northern Flicker pair. 
breeding attempts have been documented only 
rarely across all species of birds. It has been found 
in Rock Pigeons (Columba livid) which may lay a 
second clutch I week after the first brood hatches, 
but bi-parental care (incubation and feeding) 
occurs at both nests (Hurley 1980). Similarly, 
some Common Terns (Sterna hirundo) laid a 
second clutch while still caring for the first clutch 
(Moore and Morris 2005) and a population of 
Whiic-rumped Swiltlets (Ae rod ramus spodiopy- 
gius) regularly laid a second clutch in the same 
nest as the first, while the first nestling was still 
there {Jamieson et al 1987). 
The male Northern Flicker, in the case we 
observed, successfully raised four nestlings to 
fledging without the female providing any food 
from day 5 to fledging. The male was also able to 
incubate at night at the second nest and to take 
daytime incubation shifts because nestlings at the 
first nest were sufficiently old to thcrmoregulate 
without brooding. The male seemed to be able to 
successfully divide his care between two nests 
early but. apparently it became difficult after the 
first brood fledged. Perhaps once fledglings were 
mobile, it was too time-consuming to keep track 
of their locations on the landscape, and to fly to 
the second nest for incubation shifts. 
During incubation at typical flicker nests, the 
eggs are covered 99% of the time with daytime 
bouts alternating between partners (Wiebe 2008). 
No female continued with the breeding attempt 
after mate loss during incubation; whereas, some 
males continued but had low (50%) hatching 
success of the eggs (Wiebe 2005). Thus, it was not 
surprising the female we observed abandoned the 
second nest once the male stopped incubation, 
although whether females are unable, or only 
unwilling to incubate alone because of life-history 
trade-offs is not known. 
There are a few explanations for why this pair 
attempted two broods. We do not know whether the 
female abandoned the first nest after being trapped 
and banded while incubating. Abandonment occurs 
only in 2% of cases, and we have not observed 
birds start a new nest nearby while the previous 
nest was still active. Alternatively, the female may 
have stopped caring for the nestlings alter hatching 
because she chose not to invest further in a brood 
w ith low reproductive value (i.e., containing only 4 
nestlings from the original 8 eggs, flickers typically 
fledge -90% of nestlings that hatch, Wiebe 2005). 
Female desertion of young nestlings may lead to 
reproductive gains if females can secure a second 
mate (Wiebe 2005, Wiebe and Kempenaers 2009). 
However, polyandry in this population seems 
constrained by available males and the female 
may have been limited to attempting a second 
brood with the current male. Polyandmus flickers 
are significantly older than monogamous females 
(Wiebe and Kempanaers 2009) and the female in 
our observations was fairly old. at 4 years. Thus, 
she was within the age class most likely to 
