As one of
the most abundant and visible terrestrial bird breeding
in the Arctic, the Lapland Longspur is certainly the
most common passerine nesting on Bylot Island. During
the summer, it can be observed nesting on the tundra,
between two hummocks (small mounds in the ground), or
feeding on seeds and small insects.
As other Arctic-nesting birds, Lapland Longspurs are constrained
by a very short time period during which they can reproduce. Summer
is short in the Arctic and fledglings need a certain time to grow
enough to be ready for the fall migration. In these conditions,
it has been noticed that earlier nesters have a better chance
to successfully reproduce (have young and bring them to maturity).
Studying the breeding ecology of the Lapland
Longspurs can provide interesting insights on how Arctic-breeding
songbirds adapted to their harsh breeding environment. For
this reason, Lapland Longspur nests are searched and monitored
in the Qarlikturvik Valley of Bylot Island. Nests are found
opportunistically, when a female flushes from the nest as
we walk nearby. If possible the egg laying date (date when
the first egg is laid) is noted, as well as the hatching
date (date when the first egg hatches) and the clutch size
(number of eggs in the nest). All nestlings and adults are
also marked with a leg band, which could help identifying
birds in the future.
Egg-laying and Egg-hatching
Over the years, egg-laying and egg-hatching dates varied, probably
reflecting variations in the environmental conditions themselves.
Interestingly, on three occasions over last four years (2004 to
2007) longspurs have been initiating their nest from 3 to 5 days
later than usual. On average, the first egg is laid 18 June and
the first hatching date is 3 July.
As for the laying dates, mean clutch sizes vary from year to
year. The overall average number of eggs laid by Bylot Island
Lapland Longspurs is 5.3 per nest.
Nesting success represents the proportion
of all nests that hatched at least one egg. On Bylot Island, the
main cause of nesting failure for longspurs is predation. On average,
nesting success is 48% but this parameter varies considerably
among years (minimum: 9%, maximum: 82%). It is interesting to
note that longspurs had high nesting successes during the 2000,
2004 and 2007 lemming peaks.