PHOTOGRAPHIC GUIDE TO SNOWY OWL CHICKS
DEVELOPMENTAL COMPARISONS & PREDICTING THE SEX OF CHICKS
Below, the crew documented side-by-side head-on comparisons of chick development throughout stages 3-7, as well as primary wing development comparisons.
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All 6 chicks were sexed using methods outlined in the publication titled 'Sexing Young Snowy Owls' (Seidensticker et al. 2011), described below.
IN THIS SECTION
Side-by-side comparisons of chick growth & plumage for stages 3 - 7
Chick Development
STAGE 3
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11 DAYS OLD
Chick 06
14 DAYS OLD
Chick 05
STAGE 4
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18 DAYS OLD
Chick 03
20 DAYS OLD
Chick 01
STAGE 5
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22 DAYS OLD
Chick 01
27 DAYS OLD
Chick 06
STAGE 6
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30 DAYS OLD
Chick 06
35 DAYS OLD
Chick 01
STAGE 7
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38 DAYS OLD
Chick 01
39 DAYS OLD
Chick 02
Primary Feathers
In the following photos, the team documented primary flight feather growth, from quill emergence in stage 3 to fully grown flight feathers in stage 6
STAGE 3: days 8 - 14
Primary flight feather quills have begun to emerge in pin
STAGE 4: days 15 - 21
Primary flight feathers have begun to erupt from their sheaths
STAGE 5: days 22 - 28
Primary flight feathers have erupted from their sheaths
STAGE 6: days 29 - 35
Primary flight feathers are nearly fully grown in
PREDICTING THE SEX OF CHICKS
The crew was able to predict the sex of the six chicks: Chicks 01, 02, and 03 were sexed as males, and Chicks 04, 05, and 06 were sexed as females.
Sex is predicted based on plumage. The primary flight feathers of females are more heavily marked and characterized by dark bars that touch the rachis (feather shaft near the center of the feather), whereas the primary flight feathers of males are characterized by dark spots that do not touch the rachis, and are less heavily marked and more white in appearance. Additionally, female Snowy Owl chicks have a sooty gray body plumage while males are light gray. These methods can be used to predict the sex of Snowy Owls through their first winter.
BELOW, the chicks on the left are males and the chicks on the right are females. Note the darker sooty body plumage of the females vs the males.
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BELOW, the wing spreads on the left are males and the wing spreads on the right are females. Note the white, spotted primary feathers of the males and the dark, heavily barred primaries of the females.
Chloe Hernandez (left), Denver Holt (center), and Solai Le Fay (right) in Utqiaġvik, Alaska in July 2022
Citations
Holt, D.W., K. Gray, M.T. Maples and M.A. Korte. 2016. Mass growth rates and plumage development, and related behaviors of Snowy Owl (Bubo scandiacus) chicks. Journal of Raptor Research. 50: (2).
Seidensticker, M.T., D.W. Holt, J. Deteinne, S. Talbot, and K. Gray. 2011. Sexing Young Snowy Owls. Journal of Raptor Research 45: 281-289.
Recommended Citation
Le Fay S. S., Hernandez C. Y., and Holt D. W. 2023. A PHOTOGRAPHIC GUIDE TO AGING AND SEXING SNOWY OWLS FROM HATCHING TO FLEDGING. Owl Research Institute, Special Publication Number 1, Charlo, Montana, USA.
Photographic Guide to Snowy Owl Chicks
Denver W. Holt. 2022. Why Are Snowy Owls White and Why Have They Evolved Distinct Sexual Color Dimorphism? A Review of Questions and Hypotheses. Journal of Raptor Research 56(4), 440-454