Reproduction and Early Life of the Northern Pygmy-Owl

The life cycle of the Northern Pygmy-Owl (Glaucidium gnoma) is largely unknown due to lack of research on this bird in general. However, reproduction and early life have seen some recent-ish research and some valuable basics have been discovered.

 

The northern pygmy owl nests in tree crevices, these can be naturally occurring or those made by woodpeckers (Birds of North America; Darling, 2003). It is thought that the most common woodpecker cavities used are those of the Northern Flicker’s and the Hairy Woodpeckers (Darling, 2003).

 

 

 

There are some cases of a nest being reused by the same bird but it is suspected that this is rare and locating new nesting spots may be more prevalent (Deshler & Murphy, 2012; Birds of North America). While the owls are breeding the nest is thought to only ever be inhabited by the female and her fledglings, the male will not enter the nest and consequently will not be of assistance with incubation (Frye & Jageman, 2012; Birds of North America).

 

The female Northern Pygmy-owl will lay her clutch in mid to late April (Birds of North America; Deshler & Murphy 2012). At maximum one egg can be laid per day however, it can take up to two days before another egg is laid (Birds of North America; Deshler & Murphy 2012). The range in number eggs laid in one clutch tends to vary between 2-7, though the more common range is thought to be around 4-7 eggs (Birds of North America; Deshler & Murphy 2012). The eggs will then take about one month to hatch, it is thought that this occurs asynchronously however, this requires further research (Deshler & Murphy 2012; Birds of North America). It takes another month before they are fully fledged (Deshler & Murphy 2012). It is thought that from this point they may require another month before they can be left to their own devices, this is around mid to end of June when the young will disperse (Deshler & Murphy, 2012; Frye & Jageman, 2012; Birds of North America).

 

 

What is most interesting about this species is that the females size negatively correlates with the number of eggs she will lay (Deshler & Murphy, 2012). It has been hypothesized that smaller sized females may have less internal costs associated with self maintenance allowing for more resources to be allocated to her offspring (Deshler & Murphy, 2012). Another interesting finding is that smaller females will lay their eggs earlier than the larger females by almost a week (Deshler & Murphy, 2012).

 

The consumption of mammals may also be a contributing factor for females to lay their eggs earlier (Murphy, 1986; Deshler & Murphy, 2012). It has been well accepted that early breeders in northern regions tend to have higher success rates as they have more time to develop hunting skills and build up fat stores for winter – a feature observed across multiple species (Wiggins, 1991). In addition, some have noted that larger sized birds may have reduced maneuverability (Hamer & Furness, 1987). If this is true for the Northern Pygmy-owl, a smaller body size in females would be advantageous, however as is true for most questions about the Northern Pygmy-owl, more research is required.

 

To summarize, the Northern Pygmy-owls reproductive and early life cycle has only begun to be understood. We look forward to learning more about these curious little creatures.

 

 

 

 

 

SOURCES

Darling, L. M. B.C Ministry of Water, Land and Air Protection Biodiversity Branch (2003) Status of                         the Vancouver Island Northern Pygmy-Owl (Glaucidium gnoma swarthi) in                                            British Columbia. Wildlife Bulletin.

Deshler, J. F. & Murphy, M. T. (2012) The Breeding Biology of the Northern Pygmy-Owl: Do the                               smallest of the small have an advantage? The Condor. 114 (2), 314-322.

Frye, G. G. & Jageman, H. R. (2012). Post-Fledging Ecology of Northern Pygmy-owls in the rocky                              mountains. The Wilson Journal of Ornithology 124(2): 199-207.

Hamer, K. C, & Furness, R. W. (1987). Parental Investment and Brood Defense by Male and Female                       Great Skuas Catharacta-Skua – The influence of food-supply, laying date, body size and                       body condition. Journal of Zoology. 230, 7-18.

Murphy, M. T. (1986). Body Size and Condition, Timing of Breeding, and Aspects of Egg Production                          in Eastern Kingbirds. American Ornithology Society. 103 (3), 465-476.

Wiggins, D. A. (1991). Natural Selection on Body Size and Laying Date in the Tree Swallow.                                      Evolution. 45 (5). 1169-1174.