A large body of literature showed that upland farms, especially those with homogeneous landscape, have largely reduced the diversity and density of amphibians. Not many studies have been conducted to examine amphibian’s distribution in wetland farms, although rice fields and cranberry farms cover large areas globally. My study examined cranberry farms’ anuran habitat function in the Pine Barrens of New Jersey. Two questions were asked: whether the diverse habitats within cranberry farms can support anurans with different hydrology requirement; whether human’s agricultural activities can impact or benefit anuran’s survival. From 2006 to 2008, I conducted anuran vocal surveys in three active and three newly abandoned farms, which had the same farm infrastructure but no human activities. I surveyed the cranberry cultivation beds (bogs), main irrigation ditches and reservoirs within both farm types. I applied a modeling technique that takes account of the imperfect detectability of vocal survey. With the model result, I compared the density and the probability of absence of each species among the three habitats and between active and abandoned farms.
Results/Conclusions
Using model selection criteria, I found for all four species, there was interaction effect between the habitat types and the farm abandonment statues. Rana sphenocephala and R. virgatipes exhibited higher density in abandoned farms. R. virgatipes also showed preference of the reservoir habitat, concurring with their documented preference of open-water. R. sphenocephala had very low occurrence in active farms. Fowler’s toad Bufo woodhousii fowleri had the highest density in the ditch habitat of active farms, maybe due to less predation. They showed preference of the reservoir habitat in abandoned farms. Lastly, green frog R. clamitans exhibited a very intriguing preference of the active cultivation bogs. Green frog’s chronology data showed their activities in active bogs extended into August during the three-year survey, while in the abandoned bog habitat, their activities dialed down much earlier, probably because abandoned farms were dry in late summer with little natural precipitation. Green frog’s prolonged activities in active farms coincided with the persist water level in the active bogs managed by farmers. I concluded that active cranberry farms can provide habitat for the targeted species except R. sphenocephala; active farms are beneficial to the survival of B. woodhousii fowleri and R. clamitans, probably because of the stabilized hydrological condition and reduced predation due to human activities.
