Fairfax County Park Authority, Huntley Meadows Park, Virginia
Wetland losses have accelerated in the past 20 years resulting in significant habitat loss for obligate wetland species. Many marsh bird populations are declining as a result of wetland degradation and loss of wetland habitat. During the 1980’s and early 1990’s, the 50 acre Central Wetland at Huntley Meadows Park, in Fairfax County, Virginia, gained national notoriety for breeding marsh birds including rails, grebes and bitterns. Suburban development and stormwater pollution resulted in the degradation of the Central Wetland and the marsh birds stopped breeding in 1994. In 2014, the Central Wetland at Huntley Meadows Park underwent a large scale restoration project. The restoration project goals were to restore wetland ecosystem function, increase biodiversity and install control gates to allow staff to manage the wetland water levels.
David Lawlor is the Natural Resource Manager responsible for managing the wetland. Mr. Lawlor can influence vegetative communities and wildlife habitat by adjusting water levels. Water level management plans are created for each year and staff attempt to provide the best quality habitat possible for a list of target species. Marsh birds including American bitterns (Botaurus lentiginosus), least bitterns (Ixobrychus exilis), Virginia rails (Rallus limicola), king rails (Rallus elegans) and pied-billed grebe (Podilymbus podiceps) are on the list of target species used to guide management decisions. These marsh birds have been seen and heard with more regularity since the restoration project completed and king rails bred in the wetland in 2016 for the first time in almost 20 years.
Mr. Lawlor and his team will use the Wildlife Acoustics SM4 recorders to monitor the Central Wetland for breeding calls of these secretive marsh birds to track their temporal use of the wetland. Mr. Lawlor intends to correlate the timing and frequency of marsh bird use of the Central Wetland with water level management practices. The information will be instrumental in guiding water level management plans in the future to provide optimal marsh bird habitat in the Central Wetland.
After identifying quality nesting habitat, the Huntley Meadows team set up Wildlife Acoustics SM4 recorders in the Central Wetland Park on March 27th in anticipation of the marsh bird’s arrival in early April. The data will be analyzed using Wildlife Acoustics Kaleidoscope Pro software with acoustic Cluster Analysis. Logarithms will be created using Kaleidoscope Pro software for breeding calls of each species. The species data will be analyzed for frequency of calls, temporal duration of stay and estimated location to help guide future water level management plans.
David Lawlor, Natural Resource Manager at Huntley Meadows Park programmed and deployed two SM4 recorders in March 2019 to record calls of secretive marsh birds in a recently restored 50 acre wetland. The marsh birds previously bred in the wetland on a regular basis in the 1980’s and 1990’s but their numbers have declined over the past 20 years and few have bred in recent years. The specific marsh birds targeted in this survey include American bitterns (Botaurus lentiginosus), least bitterns (Ixobrychus exilis), Virginia rails (Rallus limicola), king rails (Rallus elegans) and the pied-billed grebe (Podilymbus podiceps). The recorders will allow consistent and significant trend data to track the birds use of the wetland over time and use the data to guide water level management plans in the future.
The SM4 recorders were monitored every two weeks to ensure proper operation, adequate battery supply and memory. Staff removed the recorders from the wetland in mid- June. The collected data was downloaded and will be analyzed using Kaleidoscope Pro software and the cluster analysis methodology.
Ali Donargo, Sales Associate with Wildlife Acoustics invited Mr. Lawlor to a Wildlife Acoustics SM4 and Kaleidoscope Pro workshop at the American Society of Mammologists in Washington DC. Ms. Donargo also coordinate a Kaleidoscope Pro software tutorial after the workshop with Dave Roberts, Audio Engineer. This training provided a good base knowledge for using the software and the clustering capabilities. Many thanks to Ali and Dave for their generosity and support!
The goal of the Marsh Bird Research Project at Huntley Meadows Park is to document rare marsh birds breeding in the recently restored Central Wetland. There were no reports of targeted marsh birds breeding or sightings of chicks in the Central Wetland in 2019. Although it appears no breeding occurred in 2019, park staff will analyze the acoustic data to determine if any of the six target marsh birds utilized the Central Wetland in 2019 to help guide future management of the wetland water levels.
David Lawlor, Natural Resource Manager at Huntley Meadows Park, set two Wildlife Acoustic SM4 Monitors in the 50-acre Central Wetland to collect acoustic data from April to July. The 500 gigs of data were downloaded to the Fairfax County Government server after working with the county IT department on where and how to properly store the massive volume of data.
He created Advanced Classifiers for each of the rare bird species using the Kaleidoscope software to expedite searching the massive amounts of data for the bird calls. The classifiers may need some tweaking because more false positives are reported than expected. The data is currently being processed but will take some time. No confirmed marsh bird calls have been found to date.
On a lighter note, during the spring and summer of 2019, park staff collaborated with a local college to conduct frog research in the park using SM2 recorders. Three SM2 recorders were set up in the park’s wetlands. The older model SM2’s recorders don’t have built in security options, so they are attached to a piece of plywood which is secured to a tree using screws.
The selected sites were intentionally thick and remote to avoid vandalism or theft. One recorder could not be located by grad students while checking battery levels and SD card capacities during a biweekly inspection. Mysteriously they found one microphone with the cable cut cleanly presumably by a knife. But the recorder couldn’t be found and was assumed stolen. The recorder was attached to a gum tree in the middle of blackberry thicket on the edge of a wetland and seemed like an odd place for a thief to tromping through the park. Dave Lawlor investigated the missing recorder a few days later. He found the second microphone; its cable had been cut cleanly too but no recorder was found. However, the tree the recorder had been mounted on was gone! A beaver had cut down the 20’ gum tree and drug it into the wetland, cutting the microphone cables cleanly as if they were annoying vines slowing the beavers progress. Dave searched up and down the wetland for a tree with a recorder attached but to no avail. The beaver must have incorporated the tree and the SM2 recorder into its’ food cache, dam or lodge. That’s one tough beaver!!!