Baseline and 3-Year Post-restoration Bird Communities at Big Meadow Bog, Brier Island, Nova Scotia

Anticipating the opportunity to restore the historic hydrologic conditions in Big Meadow Bog (BMB), it was important to assess the current status of key faunal taxa to provide a baseline for evaluating potential changes following restoration and assessing success. To accomplish this, bird communities were surveyed in swamp, lagg, and bog habitats along two transects associated with BMB—northwest Big Meadow (NWBMB) and southeast Big Meadow (SEBMB), and one transect at a reference area associated with Lost Bog. Transect points were surveyed during the breeding season in 2015–2018 and 2021. Ditches were plugged and water levels were raised in BMB during the fall of 2017, so bird surveys in 2015–2017 preceded water level manipulation, while those in 2018 and 2021 followed the manipulation. Overall, the bird communities were dominated by herring gulls (Larus smithsoniansus), regardless of general transect location or habitat type. This result was driven mainly by high numbers (n = 3162) in the bog at NWBMB but to a lesser extent moderate numbers (n = 723) at SWBMB. Common yellowthroat (Geothlypis trichas; n = 86), American redstart (Setophaga ruticilla; n − 49), song sparrow (Melospiza melodia; n = 40), and black-throated green warbler (Setophaga virens; n = 33) were the next most common species overall. A total of 46 of the 83 breeding species known from Brier Island were detected across all surveys. Lost Bog and SEBMB had the highest number of species overall (n = 38) and NWBMB the lowest (n = 16). Ordinations revealed clear differences in the bird communities associated with BMB and the reference system at Lost Bog. Differences were most pronounced at NWBMB, where there were the fewest species, the lowest diversity and evenness, the lowest numbers of individuals apart from herring gulls and the fewest species of conservation concern, reflecting the highly degraded nature of the habitat around NWBMB. Based on their similarity to those at the Lost Bog reference site and lower numbers of gulls in the southern part of BMB, it is expected that bird communities at SEBMB will be first to return to a full array of typical peatland species, possibly as quickly as 10–15 years. Recovery of bird communities in the northern part of BMB is likely to take several more decades and initiation of recovery will not progress until there is substantial reduction in the herring gull population. Continued systematic monitoring of bird and vegetation communities at the site will be necessary into the indefinite future to fully assess success of the restoration from an avian perspective.