Looking Back: 30 Years of Marsh Monitoring Program Science

Big numbers and the people behind them

Between 1995 and 2024, 2000 observers logged 92,000 bird and frog point counts (surveys). They detected over 248,000 individual frogs of 11 species, and 874,000 individual birds of over 300 species. As if that wasn’t impressive enough, the program’s participants have logged 180,000 hours to date worth $3.6 million! Obviously a huge thank you is in order to the many dedicated volunteers and others involved: we simply could not have accomplished all of this without your valued support, so thank you very much.

What’s more impressive, however, is what staff and volunteers have collectively accomplished with the GLMMP and other related datasets for marsh bird and frog conservation. As with all of our citizen science monitoring programs at Birds Canada, science drives our conservation efforts to protect birds and wildlife. So then, what science has come out of the GLMMP over the years, and how has it protected or conserved marsh birds and frogs, you might ask?

The program has produced a large suite of diverse data and science products that have set the stage for many different wetland conservation actions. What follows is an overview of these various products, and because we publish most of our science in scholarly peer-reviewed journal articles, there are lots of links to primary sources throughout, and there’s an accompanying reference list at the end, so you can find more details, if desired. 

Big Impact and the Science Behind it

We report annual population indices and trends for dozens of marsh bird and frog species across the Great Lakes in: a) the GLMMP annual newsletter, The Marsh Monitor (latest issue here: 1); b) GLMMP program reports (latest was at the program’s 25-year mark: 2); and c) robust, detailed analyses (e.g., 3, 4, 5, 6). These works provide an authoritative voice that raises awareness of declining marsh bird and frog populations and associated conservation issues, which in turn spark wetland restoration and protection projects throughout the Great Lakes. Now, stop and think about this for a moment: it means that just about every funding proposal for any wetland restoration project that aims to benefit wetland wildlife in the Great Lakes points to the GLMMP and these science products to justify the need for the work! Now that’s paving the way for a LOT of wetlands to be restored and conserved for marsh birds and frogs!!

Every 3 years, we publish “indices of biotic condition” for marsh birds and frogs throughout the Great Lakes in Canada and the U.S. (latest methods: 7; previous exploratory work: 8, 9). You can think of these indices as a score of how well the populations are doing, out of 10. They’re published in the State of the Great Lakes Report (we’ve done this 5 times now; the latest was in 2022: 10), which is required by the governments of Canada and the U.S. under the Great Lakes Water Quality Agreement. These reports are critical for attracting the investment of hundreds of millions of dollars annually (!) for wetland restoration through the Great Lakes Freshwater Ecosystem Initiative in Canada and the Great Lakes Restoration Initiative in the U.S.

Birds Canada staff use GLMMP data and other datasets to test the effectiveness of conservation actions for marsh birds and frogs, such as control of invasive Common Reed (spoiler: it works really well for birds; 11), and wetland restoration techniques used by Migratory Bird Joint Ventures (spoiler: this also works really well; 12). We also measure the effectiveness of remedial actions for restoring wetland wildlife in Great Lakes Areas of Concern (e.g., 13, 14), and we assist decision-makers by identifying the best wetlands for protection, and the worst wetlands for restoration (e.g., 15, 16). These products ensure that the most effective conservation actions are done in the best places, so that marsh birds and frogs thrive in the Great Lakes.

Using GLMMP data and other datasets, we’ve investigated how various factors, such as wind and time of day, influence the detection of elusive marsh birds during surveys (17, 18, 19), and we’ve used this information to improve the effectiveness of marsh bird monitoring in the field (20). We’ve explored ways to obtain more precise population information for marsh birds (21). We’ve researched the influence of fluctuating water levels on marsh birds (22, 23, 24), and we’ve helped design GLMMP-based indicators to better evaluate how water level regulation in Lake Ontario influences marsh birds (25). We’ve demonstrated the importance of vegetation grazing by foraging muskrats, and other wetland disturbances, for maintaining important marsh bird and frog habitat features (26, 27). We’ve described in detail the best habitats for marsh birds and frogs (28, 29, 30), and we’ve completed some of the most robust analyses to date showing the negative effect of urban sprawl and other types of habitat loss on these animals (e.g., 31, 32). And we’ve examined the influence of climate warming on marsh-breeding frogs (33). These various different studies ensure that we’re surveying marsh birds and frogs efficiently and effectively, and that we have a thorough understanding of the habitat features that marsh birds and frogs need to thrive. As a result, wetland managers and other decision-makers have robust, reliable information with which to conserve and protect habitat for these important animals.

The following quotes from GLMMP volunteer scientists are a fitting “final word,” which demonstrate how the program leads to conservation action:

• a) “The GLMMP has introduced me to a world I would not have otherwise known, so I see the program as a means to preserve that world for future generations;”
• b) “Because of my GLMMP surveys, I have a different level of awareness of wildlife in the surrounding wetlands;”
• c) “We used our GLMMP data from our local wetland as part of our testimony to successfully stop the creation of a golf course around the headwaters of this valuable wetland.”

So there you have it: the conservation actions brought about by 30 years of GLMMP science is impressive indeed! As we’ve seen, the data and science products produced by the program’s staff and volunteers provide an authoritative voice, critical funding, sound guidance, and robust, reliable information for conservation and protection of Great Lakes marsh birds and frogs that would otherwise not exist. This really speaks to the power of Birds Canada’s approach of engaging volunteers so together we can drive conservation efforts to protect birds and other wildlife.

A final thought: as I noted above, we simply could not have accomplished all of this without the valued effort of volunteer scientists, so thank you very much again for your dedicated support. The program would also not be where it is today without ongoing financial support, for which the following have been essential: Environment and Climate Change Canada, Ducks Unlimited Canada, Eastern Habitat Joint Venture, Wildlife Habitat Canada (primarily from funds generated by the purchase of Canadian Wildlife Habitat Conservation Stamps by waterfowl hunters), and private donors. There have also been dozens and dozens of other supporters of the program over the years for which we are truly grateful. Many thanks, again, to all of you: it’s been a very rewarding “30-year-science-and-conservation-ride.” The birds and frogs are especially thankful too, so I hear, for what we’ve collectively accomplished on their behalf over the years. 

References

1. Birds Canada, 2024. Things are getting really interesting! The Marsh Monitor 30:1–14.
2. Tozer DC, 2020. Great Lakes Marsh Monitoring Program: 25 years of conserving birds and frogs. Birds Canada, Port Rowan, Ontario, Canada.
3. Tozer DC, 2016. Marsh bird occupancy dynamics, trends, and conservation in the southern Great Lakes basin: 1996 to 2013. Journal of Great Lakes Research 42:136–145.
4. Kirchin MJ, Fiorino GE, Grabas GP, Tozer DC, 2020. Changes in abundance of Least Bitterns in Ontario, 1995–2019. Ontario Birds 38(3):114–129.
5. Tozer DC, Bracey AM, Fiorino GE, Gehring TM, Gnass Giese EE, Grabas GP, Howe RW, Lawrence GJ, Niemi GJ, Wheelock BA, Ethier DM, 2024. Increasing marsh bird abundance in coastal wetlands of the Great Lakes, 2011–2021, likely caused by increasing water levels. Ornithological Applications 126:duad062.
6. Tozer DC, Bracey AM, Brady VJ, Chislock MF, Ciborowski JJH, Cooper MJ, Fiorino GE, Gehring TM, Gnass Giese EE, Grabas GP, Harrison AM, Howe RW, Lamberti GA, Lawrence GJ, Niemi GJ, Wheelock BA, Uzarski DG, Wheelock BA, Ethier DM, 2025. Occurrence patterns and trends of frogs in coastal wetlands of the Great Lakes call for further habitat restoration. Ecosphere e70248.
7. Howe RW, Niemi GJ, Bracey AM, Brady V, Elliott L, Fiorino GE, Gaul W, Gehring TM, Gnass Giese EE, Grabas GP, Lawrence G, Norment CJ, Panci H, Tozer DC, Uzarski D, Walton NG, Bridget Wheelock, 2023. An index of biotic condition (IBC) using birds as indicators of coastal wetland quality in North America’s Laurentian Great Lakes. Ecological Indicators 156:111174.
8. Chin ATM, Tozer DC, Fraser GS, 2014. Hydrology influences generalist-specialist bird-based indices of biotic integrity in Great Lakes coastal wetlands. Journal of Great Lakes Research 40:281–287.
9. Chin ATM, Tozer DC, Walton NG, Fraser GS, 2015. Comparing disturbance gradients and bird-based indices of biotic integrity for ranking the ecological integrity of Great Lakes coastal wetlands. Ecological Indicators 57:475–485.
10. Tozer DC, Howe RW, Niemi GJ, Gnass Giese EE, Bracey AM, Fiorino GE, Gehring TM, Norment CJ, Lawrence G, 2022. Sub-indicator: coastal wetland birds and Sub-indicator: coastal wetland amphibians. In State of the Great Lakes 2022 Technical Report (Environment and Climate Change Canada and the U.S. Environmental Protection Agency). Cat No. En161-3/1E-PDF. EPA 905-R22-004.
11. Tozer DC, Mackenzie SA, 2019. Control of invasive Phragmites increases marsh birds but not frogs. Canadian Wildlife Biology and Management 8:66–82.
12. Tozer DC, Steele O, Gloutney M, 2018. Multispecies benefits of wetland conservation for marsh birds, frogs, and species at risk. Journal of Environmental Management 212:160–168.
13. Cartwright L, Cvetcovik M, Tozer D, Chow-Fraser P, 2013. URBAN: development of a citizen science biomonitoring program based in Hamilton, Ontario, Canada. International Journal of Science Education, Part B 5:93–113.
14. Cartwright LA, Hayes S, Tozer DC, Clayton D, Burns M-A, Lewis D, Gaetz N, Shrestha N, 2021. Assessing terrestrial wildlife populations in the Toronto and Region Area of Concern. Journal of Great Lakes Research 47:273–282.
15. Tozer DC, Stewart RLM, Steele O, Gloutney M, 2020. Species habitat relationships and priority areas for marsh-breeding birds in southern Ontario. Journal of Wildlife Management 84:786–801.
16. Grand J, Saunders SP, Michel NL, Elliott L, Beilke S, Bracey A, Gehring TM, Gnass Giese EE, Howe RW, Kasberg B, Miller N, Niemi GJ, Norment CJ, Tozer DC, Wu J, Wilsey C, 2020. Prioritizing coastal wetlands for marsh bird conservation in the U.S. Great Lakes. Biological Conservation 249:108708.
17. Tozer DC, Abraham KF, Nol E, 2006. Improving the accuracy of counts of wetland breeding birds at the point-scale. Wetlands 26:518–527.
18. Tozer DC, Abraham KF, Nol E, 2007. Short call-broadcasts fail to detect nesting Least Bitterns (Ixobrychus exilis). Northeastern Naturalist 14:637–642.
19. Tozer DC, Drake KL, Falconer CM, 2016. Modeling detection probability to improve marsh bird surveys in southern Canada and the Great Lakes states. Avian Conservation and Ecology 11(2):3.
20. Tozer DC, Falconer CM, Bracey AM, Gnass Giese EE, Niemi GJ, Howe RW, Gerhing TM, Norment CJ, 2017. Influence of call broadcast timing within point counts and survey duration on detection probability of marsh breeding birds. Avian Conservation and Ecology 12(2):8.
21. Bianchini K, Tozer DC, 2023. Using Breeding Bird Survey and eBird data to improve marsh bird monitoring abundance indices and trends. Avian Conservation and Ecology 18(1):4.
22. Farley EB, Schummer ML, Leopold DJ, Coluccy JM, Tozer DC, 2022. Influence of water level management on vegetation and bird use of restored wetlands in the Montezuma Wetlands Complex. Wildlife Biology e01016.
23. Schummer ML, Eason KM, Hodges TJ, Farley EB, Sime KR, Coluccy JM, Tozer DC, 2021. Response of aquatic macroinvertebrate density and diversity to wetland management and structure in the Montezuma Wetlands Complex, New York. Journal of Great Lakes Research 47:875–883.
24. Hohman TR, Howe RW, Tozer DC, Gnass Giese EE, Wolf AT, Niemi GJ, Gehring TM, Grabas GP, Norment CJ, 2021. Influence of lake-levels on water extent, interspersion, and marsh birds in Great Lakes coastal wetlands. Journal of Great Lakes Research 47:534–545.
25. Denomme-Brown ST, Fiorino GE, Gehring TM, Lawrence GJ, Tozer DC, Grabas GP, 2023. Marsh birds as ecological performance indicators for Lake Ontario outflow regulation. Journal of Great Lakes Research 49:479–490.
26. Baici JE, Martin KD, Newa SL, Burgess T, Greenhorn JE, Kielar SR, Menelon L, Melvin GP, Persad R, Sadowski C, Solmundson K, Tozer DC, Ward M, Bowman J, 2024. Relationships between muskrat density and avian and anuran richness in Great Lakes coastal wetlands. Wetlands 44:38.
27. Tawa V, Tozer DC, Green DM, 2024. Natural disturbance allows multiple anuran taxa to persist in a dynamic wetland complex. Journal of Wildlife Management 88:e22617.
28. Tozer DC, Nol E, Abraham KF, 2010. Effects of local and landscape-scale habitat variables on abundance and reproductive success of wetland birds. Wetlands Ecology and Management 18:679–693.
29. Panci HG, Niemi GJ, Regal RR, Tozer DC, Gehring TM, Howe RW, Norment CJ, 2017. Influence of local, landscape, and regional variables on Sedge and Marsh Wren occurrence in Great Lakes coastal wetlands. Wetlands 37:447–459.
30. Elliott LH, Bracey AM, Niemi GJ, Johnson DH, Gehring TM, Gnass Giese EE, Grabas GP, Howe RW, Norment CJ, Tozer DC, Igl LD, 2023. Application of habitat association models across regions: explanatory power retained in a case study of wetland birds. Ecosphere 14:e4499.
31. Studholme KR, McFarlane Tranquilla L, Berrigan L, Achenbach L, Tozer DC, 2022. Land cover habitat associations of breeding marsh birds and priority waterfowl differ in eastern Canada. Avian Conservation and Ecology 17(1):33.
32. Studholme KR, Fiorino GE, Grabas GP, Tozer DC, 2023. Influence of surrounding land cover on marsh-breeding birds: implications for wetland restoration and conservation planning. Journal of Great Lakes Research 49:318–331.
33. Walpole AA, Bowman J, Tozer DC, Badzinski DS, 2012. Community level response to climate change: shifts in anuran calling phenology. Herpetological Conservation and Biology 7:249–257.
34. COSEWIC, 2009. COSEWIC assessment and update status report on the Least Bittern Ixobrychus exilis in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa.
35. COSEWIC, 2008. COSEWIC assessment and update status report on the Western Chorus Frog Pseudacris triseriata Carolinian population and Great Lakes/St. Lawrence – Canadian Shield population in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa.