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US Fish & Wildlife Service FieldNotes

Mayflies, Management, and Orchids at Ottawa National Wildlife Refuge

Region 3, June 23, 2015
Cluster of eastern prairie fringed orchids.
Cluster of eastern prairie fringed orchids. - Photo Credit: n/a
Mayflies swarm and land on volunteer Sarah LeVane as she monitored the orchids.
Mayflies swarm and land on volunteer Sarah LeVane as she monitored the orchids. - Photo Credit: n/a

Ottawa National Wildlife Refuge is known primarily as one of the top places to observe migratory birds as they stop over during their migration over the Great Lakes. However, the refuge provides important wetland habitat for plant species as well. In 2007, the eastern prairie fringed orchid (Platanthera leucophaea), a federally threatened species, was observed at the refuge. Since that time, the tall, showy plants have been monitored every year. Two additional locations on the refuge have also been identified.

Biologists at the refuge have worked hard to reduce the number of invasive species such as phragmites, narrow-leaved cattail and purple loosestrife. In addition, the have managed native woody species such as dogwood and willow, which can shade out the orchid. Equipment such as the marsh master, as well as herbicides, biological controls, and prescribed fire are used to improve the quality of habitat for the orchid.

At one site the refuge has been conducting management annually for the last few years. The Young site was mowed for the last two winters and then this spring a prescribed fire was conducted. The fire was conducted early in the spring and while some individual orchids had sprouted the plants were all very young and the fire was of such low intensity that minimal impacts occurred to the orchids. The prescribed fire did help to reduce the amount of thatch at the site. While biologists at the refuge can use various management tools to reduce competition from invasive and woody plants, they are limited on their ability to control hydrology of the site.

In some areas the refuge can manipulate water levels through the use of pumps and dikes. However, at other sites there is little control and overall hydrology is determined by the level of Lake Erie. In 2012, Ohio experienced an early hot, dry spring. The populations at many orchid sites were down. However, those at the refuge remained steady. The last two years the spring weather has been more normal with this year being cooler and the rain arriving later than normal.

This year the orchids were monitored the last full week of June. In some areas the density of orchids was unbelievable! Usually when we drive by a site a handful of these tall, white orchids are visible from the road. This year driving by the site we could see over a dozen individuals! As we started our transects into the habitat, the swarms of mayflies, biting mosquitoes, and boot-deep water did not prevent us from documenting a record number of plants. Last year at the Young site we had over 300 plants total for the site. This year we had nearly four times that number with a total of over 1,300 plants for one site!

The next day we visited another site at the refuge to continue our monitoring. This second site also broke the record for the number of plants observed this year. The total number of plants observed at the refuge this year was greater than the total last year from all other sites in Ohio combined! The refuge will continue to work to manage all of its orchid sites to improve the quality of the habitat as well as survey other areas of suitable habitat to determine if orchids are present.

Contact Info: Jennifer Finfera, 614-416-8993 ext.13, Jennifer_finfera@fws.gov