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Maine Vernal Pools

This web site was designed to provide information on vernal pools for the people of Maine.

You will find a variety of resources on vernal pool ecology, the animals that breed in and use vernal pools, an explanation of state and federal regulations pertaining to vernal pools, and materials developed to assist you with field assessments and local mapping projects.

Featured Scientist - Britt ClineB. Cline

Britt’s research focuses on identifying the links between land use and amphibian post-breeding habitat.  In particular, Britt studies the juvenile stage of an iconic amphibian species in Maine, the wood frog (Lithobates sylvaticus) during the period of post-metamorphosis (when they leave natal pools where they were hatched). 

Juvenile frogs typically emerge into the terrestrial environment from their natal pool soon after metamorphosis, sometimes moving to a new breeding pool (dispersal) and sometimes returning to breed in their natal pool the following summer (philopatry).  Both dispersing and philopatric frogs may need to move across many kinds of land cover, but the ones that move to new pools will likely cover greater distances and encounter diverse vegetation.  While most amphibian research has focused on (1) breeding habitat and (2) adult frogs, Britt wants to understand how suburban development, agriculture and forestry affect the post-breeding movements of juvenile frogs, which are critical to sustaining healthy populations through gene flow.  In particular, she wants to know how juvenile frogs move across and between diverse land cover (such as lawn, agricultural fields, woodlots, and pavement) to access suitable habitat.  How far can these small frogs travel, and what kinds of land cover can they cross as they move from their natal pool to surrounding forest? 

Small-scale movement mechanisms:  Britt uses fluorescent powder and lab studies to assess the factors that may influence juvenile wood frog movements in field settings.  Here, she is measuring the lengths of individual hops for a juvenile wood frog in response to a simulated predator in the lab.

The paramount challenge, however, is that the movements of juvenile wood frogs are particularly difficult to study!  These froglets are cyptic in color and very small, weighing about 0.5 g (smaller than a dime).  To address this challenge, Britt uses a combination of techniques to directly follow frogs and assess their movements after they leave natal pools.  At the most basic, she applies fluorescent powder to each frog, which illuminates the juvenile frogs’ movement paths and footprints when fieldwork is conducted at night and under ultra-violet or blacklight conditions.  By identifying the links between wood frog breeding habitat and the surrounding terrestrial environment, Britt’s findings will help landowners understand how seasonal land management practices and development projects can be best designed to connect and protect crucial habitat for pool breeding amphibians. 

Fluorescent powder tracking: Britt uses fluorescent powder and ultra-violet light to study juvenile wood frog movements at night. Here, she is tracking a juvenile wood frog (Lithobates sylvaticus) in its terrestrial forest habitat during a movement trial after it emerges from a natal pool in 2013. This photo is taken with and without a flash and blacklight illumination.

Fluorescent powders are harmless to amphibian skin, and degrade when exposed to water and weather elements. Britt uses powders based on a polymer technology that are free of carcinogens, formaldehyde or other toxic chemicals (

Peer-reviewed Papers

Cline, B.B., and M.L. Hunter, Jr. 2014. Different open-canopy vegetation types affect matrix permeability for a dispersing forest amphibian. Journal of Applied Ecology 51:319-329,
doi: 10.1111/1365-2664.12197.

Emanetoglu, N.W., H.M. Aumann, E.M. Kus, and B.B. Cline. Submitted. A low-cost harmonic radar for tracking very small tagged amphibians. IEEE (Institute of Electrical and Electronics Engineers) Transactions on Instrumentation and Measurement.

Gardner, S.K., J. Jansuswicz, K. Hutchens, B. Cline, and V. Levesque. 2013. Socialization to interdisciplinarity: Faculty and student perspectives. Higher Education 67:255-271,
doi: 10.1007/s10734-013-9648-2.

Gardner, S.K., J. Jansuswicz, K. Hutchens, B. Cline, and V. Levesque. 2012. Interdisciplinary doctoral student socialization. International Journal of Doctoral Studies 7:377-394.


blue-spotted salamander eggs vp in winter