The Westward Expansion of the Blue Jay

Updated: May 29

Blue Jays are common in the eastern states, but since the 1970s, they have been terrorizing peanut feeders across the western states.

A Vibrant Blue Jay poses in the Rocky Mountain region.

Stories are frequently told, from the seasoned birders, of the first sightings of Blue Jays in the western United States. Birders who have been counting birds for 50 years or more, can tell you the exact date the first "backyard bully" showed up at their local feeders, town, park, etc. At the time, they likely did not know that Blue Jays would become a common sight within 30 years.



The Peanut Bandit


The Blue Jay, Cyanocitta cristata, is a member of the Corvid family. The Corvid family includes crows, ravens, and the rest of the jays. Adaptability and intelligence are synonymous with this family, so it should come as no surprise to birders that the Blue Jay would expand their range by hopping municipality to municipality (and using major riparian corridors as green interstates).


The map below shows the current range of the Blue Jay, according to eBird data from 2014 - 2018. While Blue Jays are residents throughout much of their range, there is a significant movement of the population that occurs throughout the year. You can see these movements on eBird, and it creates a spectacular short video.



Blue Jay Range Map

Updated Blue Jay Range Map


Blue Jay Sightings Increase in the West


Blue Jay records in the western states exploded in the winter of '76-77 after steadily increasing from 1970 through 1975. (Smith, 1978)


Blue Jays have been recorded many times in the western states before 1970, however, the upward trend really began its upward movement in 1972 and exploded in the winter of 1976. Is this shift in sightings a result of more birders, more surveys, or something else? We may never know, but we can assume haphazardly. Maybe we can blame Russian Olives? Or peanut feeders? You can come up with your own outrageous conspiracy theory if you would like.



Christmas Bird Count Data Trends


The Audubon Christmas Bird Count is a great opportunity to learn how the population of a resident species, like the Blue Jay, is trending. From the graphic below, you can see that CBC data is showing a decrease in relative abundance for the southeastern states, while the western states, and western provinces of Canada, are showing increases in abundance. What causes the increase in some areas and the decrease in other areas? There are many factors that are beyond the scope of this post. (Some of those factors create political friction, so I'm just avoiding them. This is a fun place, and it will stay that way!)


Relative abundance trends in Blue Jays in North America. (Meehan et all, 2018)


Range Expansion of the Blue Jay since 1970

This short video shows how the frequency of Blue Jay reports increased from 1970 to 2019.



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Credits/References

Fink, D., T. Auer, A. Johnston, M. Strimas-Mackey, M. Iliff, and S. Kelling. eBird Status and Trends. Version: November 2018. https://ebird.org/science/status-and-trends. Cornell Lab of Ornithology, Ithaca, New York.
K. Smith, Range Extension of the Blue Jay into Western North America. Bird Banding, 1978, Vol. 49, No. 3. https://bit.ly/2sxSG6O
Meehan, T.D., LeBaron, G.S., Dale, K., Michel, N.L., Verutes, G.M., and Langham, G.M. 2018. Abundance trends of birds wintering in the USA and Canada, from Audubon Christmas Bird Counts, 1966-2017, version 2.1. National Audubon Society, New York, New York, USA. (https://www.audubon.org/conservation/where-have-all-birds-gone)

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