Reverse Migration Case Studies

Reverse Migration Case Studies:

Lakewood Pumping Station, St. Louis, Minnesota - 21 Apr 2023

ebird checklist - google maps for location - archived weather conditions - surface map

Key Species: 

• 24000 American Robin 

• 4418 Fox Sparrow

A more traditional and obvious form of Adverse Weather Reverse Migration, where heavy spring snow forces migrants to retreat southwards. Generally flights of this nature have less caveats than the above case study from Zion Road - with the only one assuming that notable spring migration has occurred prior to the storm itself (i.e., deep-snow-fearing species have pushed north and are now being affected by the snow). 

Zion Road, Chatham-Kent, Ontario - 10 May 2019

ebird checklist - google maps for location - archived weather conditions - surface map

Key Species: 

• 250 Scarlet Tanager 

• 800 Chimney Swift 

• 10,000+ Swallows

• 100 Ruby-throated Hummingbirds 

A sharp cold front passed through southern Ontario overnight, bringing cold blustery northwest winds at dawn. One notable ingredient here is that early May 2019 was an "on-time" to "ahead of schedule" migration but was not advanced in terms of insect availability or leaf-out by this date. Therefore some bird species (such as those noted above, which may have been considered slightly ahead-of-schedule) decided it was in their best interest to undertake a southbound "morning flight" to reach more favourable "conditions" before settling down. 

Other Checklists: 

Hamilton, Ontario - 31 Mar, 1987

Hamilton, Ontario - 18 Mar, 1973