Fens are a newly observed habitat for Notophthalmus viridescens (Rafinesque, 1820)

Notophthalmus viridescens is a wide-ranging newt (Salamandridae) species found in North America. Endemic to the eastern United States (USA) and Canada, they are often locally abundant within suitable habitat, including throughout the State of Michigan. N. viridescens has a complex life history, including four distinct life stages: egg, larva, juvenile/eft, and adult.

Adult newts have high site fidelity, and prefer two broad categories of aquatic habitats: small to medium sized permanent bodies of water, and ephemeral wetlands (Roe and Grayson 2008. J. Herpetol. 42.1: 22–30). Adults and efts exhibit terrestrial behavior, and may be found overwintering in both wetlands and woodlands adjacent to ephemeral wetlands, marshes, ponds, rivers, and lakes (Stockwell et al. 1989. J. Herpetol. 23:409–414). They have also been reported from other wetlands including floodplains, bogs, and vernal pools (Butler et al. 2005. NENA 12:1–10). However, N. viridescens has not been reported from a fen, at any life stage.

Fens are minerotrophic peatlands, and typically manifest as open, alkaline to slightly acidic habitats. Fens were previously unknown habitat for N. viridescens. Fens are currently understood to have little to no species richness or abundance with respect to salamanders (Order: Urodela) (Stockwell et al. 1989. J. Herpetol. 23:409–414). An occasional exception in North America is Hemidactylium scutatum (Plethodontidae), which has a strong association with mosses in the genus Sphagnum (King and Richter 2022. Diversity 14:995).

A single Notophthalmus viridescens was observed traversing a lakeshore northern fen at 10:41 on 9 September 2024. The fen survey was conducted from 09:00 to 11:00 h at Lake Skegemog Wildlife Area, Clearwater Township, Kalkaska County, Michigan, USA (44.8139711°N, 85.3106061°W, WGS 84, 181.7 m elev.).

Upon initial detection and visual inspection, the specimen was determined to be an adult male. The specimen was observed for ten minutes. Upon kneeling down to observe the moving individual, it ceased moving, and then froze. Then, the specimen was photographed. The specimen remained motionless for the remaining several minutes of observation, upon which the specimen was measured. Ultimately, the individual was not collected and left in situ. The individual measured 821 mm total length, and displayed a typical wild phenotype (Figure 1).

The individual was 51 m north from the central-west shoreline of Lake Skegemog, and 48 m south from a patch of forested rich conifer swamp. Lake Skegemog has an area of 11 km², with approximately half of the shoreline being developed. The surrounding habitat is part of the Lake Skegemog Wildlife Area, which is protected and managed by the Michigan Department of Natural Resources and the Grand Traverse Regional Land Conservancy.

The weather was cloudy without precipitation; air temperature was 20.5 °C, ground temperature was recorded at 16.4 °C, and the temperature of the surface of the skin at dorsal midbody was 20 °C.

The individual was moving hastily underneath a layer of several species of sedges (Carex aquatilis, Carex buxbaumii, Carex stricta), Typha angustifolia, shrubs (Dasiphora fruticosa, Toxicodendron vernix, Chamaedaphne calyculata, Lonicera oblongifolia), and stunted conifers (Larix laricina, Thuja occidentalis, Picea mariana). The individual was observed actively walking over sphagnum mosses (Sphagnum sp.), brown mosses (Amblystegiaceae), Scorpidium scorpioides, and Utricularia intermedia. Sarracenia purpurea was the only documented predator of N. viridescens observed during the survey (Butler et al. 2005. NENA 12:1–10).

This is the first published observation of N. viridescens in a fen. This discovery deepens our understanding of the species’ habitat preferences and adaptability. Additionally, it adds another species to the expansive list of biota that are known to occur in fens; N. viridescens is significant given the apparent low caudate diversity within fens.

Fens are wetlands that exhibit considerable variation and diversity; typically they are alkaline, but can be close to neutral or slightly acidic. The necessary equipment for measuring pH was not available in the field, so the pH was not recorded. In Michigan, N. viridescens may occur in four other varieties (i.e. besides northern fen): poor fen, patterned fen, prairie fen, and/or coastal fen. Investigating the presence of N. viridescens in other types of fens would provide a more comprehensive understanding of their habitat preferences and distribution. These insights are also critical for effective habitat management of potential salamander assemblages within fens.

Fens within other U.S. states and Canadian provinces should be surveyed specifically for N. viridescens. N. viridescens efts and postbreeding adults both exhibit movement throughout terrestrial landscapes that comprise their home range (Roe and Grayson 2008. J. Herpetol. 42.1: 22–30). Further research is needed to determine the extent to which fens are utilized within these home ranges and during post-breeding dispersal.

The abundance and frequency of N. viridescens in fens is uncertain after this observation, since only one individual was encountered. Further surveys should target not only adults, but every life stage, as it is currently unclear whether N. viridescens inhabit fens during the eft, larval, and/or egg stage. Open water pools are often present within several varieties of fen, and may occasionally offer suitable breeding, egg deposition, and/or larval habitat.

The observation in this note highlights the potential diversity of habitats used by Notophthalmus viridescens, demonstrating that fens may be noteworthy components of their habitat mosaics. Future research should delve deeper into the factors influencing N. viridescens’ habitat preferences and population dynamics within fens, contributing to a better understanding of this widespread salamander’s ecology in a unique and increasingly threatened ecosystem.