Posted | filed under Weekly Reports.

As June 10 brings closer the last day of the Lesser Slave Lake Bird Observatory’s Spring Migration Monitoring program, the forest is full of love, but few migrants.

Despite the seemingly persistent high winds and rain which kept the nets shut, we continued to count birds daily. While most migrants were large flocks of Cedar Waxwings or Pine Siskins, there were Mourning Warblers and Alder Flycatchers arriving too.

We found our station’s first ever Western Kingbird (a species that can easily be found breeding around Drumheller). It’s exciting, but not necessarily shocking since it comes on the tail of recent records for several other birds more typical of southern Alberta: Willet, Western Meadowlark, Lark Sparrow, and Turkey Vulture.

Another historical event occurred – something exceedingly rare due to the importance of keeping our monitoring efforts as standardized as possible. Yet, sometimes change is necessary and we have shifted our Monitoring Avian Productivity and Survivorship (MAPS) program ten days earlier to begin May 31 instead of June 10.

Above: This Swainson’s Thrush was the first capture of an already banded bird (recapture) of MAPS 2024. Originally banded in 2020, this bird will have traveled to his wintering grounds and back 4.5 times – a one-way distance of at least 4,500 km if he winters in Southern Mexico and up to 10,000 km if he winters in Argentina. That’s at least 20,000 km traveled so far!

MAPS is a continent-wide program coordinated by the Institute for Bird Populations focused on local breeders. MAPS stations are operated six times per summer, once roughly every ten days. By banding during the breeding season, population parameters such as productivity (young produced), recruitment (young returning to breed), and survival (adults returning to breed) are estimated.

Recent studies using LSLBO data suggest that several species have significantly advanced their spring migration timing due to climate change, especially short-distance migrants (Lehikoinen et al 2019; Oliver et al. 2019). However, just because a species may be arriving earlier, does not necessarily mean they begin nesting earlier (Ahola et al. 2004; Boukherroub et al. 2024). Some species are even shortening their breeding windows with the end of breeding advancing more than the start (Hällfors et al. 2020), but others have expanded their seasons (Halupka 2017). Clearly more research is needed on the early breeding season which is missed by our usual MAPS start.

Although the weather has interfered with our first ever early MAPS round, our first captures show promise.  Around 25% of captures were of birds already banded as they return to areas they nested in previous years. Most captured males were in active breeding condition and several females were too, suggesting that they have not only built their nests, but are already laying eggs.

Not only will this shift help us capture the breeding period more confidently, it also means that we will no longer be running MAPS at the end of July when many birds have already started heading south for the winter. This will improve bird safety when staff are spread thin running two busy programs by keeping us from being overwhelmed with captures of migrants. It will also reduce our run-ins with Black Bears that become more common as the berries ripen. We look forward to establishing these earlier dates as the new normal!

By Robyn Perkins, LSLBO Bander-in-Charge


Ahola M, Laaksonen T, Sippola K, Eeva T, Rainio K, Lehikoinen E. 2004. Variation in climate warming along the migration route uncouples arrival and breeding dates. Global Change Biology 10:1610-1617.

Boukherroub S, Desrochers A, Tremblay JA. 2024. Nesting phenology of migratory songbirds in an eastern Canadian boreal forest, 1996–2020. Avian Conserv Ecol. 19(1).

Hällfors MH, Antaõ LH, Itter M, Lehikoinen A, Lindholm T, Roslin T, Saastamoinen M. 2020. Shifts in timing and duration of breeding for 73 boreal bird species over four decades. Proc Natl Acad Sci U S A. 117(31):18557–18565.

Halupka L, Halupka K. 2017. The effect of climate change on the duration of avian breeding seasons: a meta-analysis. Proceedings of the Royal Society B 284.

Lehikoinen A, Lindén A, Karlsson M, Andersson A, Crewe TL, Dunn EH, Gregory G, Karlsson L, Kristiansen V, Mackenzie S, et al. 2019. Phenology of the avian spring migratory passage in Europe and North America: Asymmetric advancement in time and increase in duration. Ecol Indic. 101(January):985–991.

Oliver R, Mahoney P, Gurarie E, Krikun N, Weeks B, Hebblewhite M, … Boelman N. 2020. Behavioral responses to spring snow conditions contribute to long-term shift in migration phenology in American robins. Environmental Research Letters, 15(4), 045003.