Port Moody Ecological Society



Northwestern Salamander (Ambystoma gracile) Monitoring Program Pilot Study, Colony Farm Regional Park - Summer 1998


Monitoring programs provide a means of measuring the health of wildlife populations and their respective ecosystems over time, thereby making them valuable conservation management tools. Amphibians are excellent target species for monitoring programs in natural areas supporting aquatic and terrestrial environments, because of their close association with both types of habitat (Heyer et al 1994). Worldwide concern about amphibian decline has led to the implementation of an international effort to document the status of amphibian populations through monitoring programs (DAPTF 1998).

1998 biophysical studies at Colony Farm Regional Park included the initiation of a monitoring program for Northwestern salamanders (Ambystoma gracile). The study investigated the validity and feasibility of using amphibian egg mass surveys and minnow trapping as monitoring techniques for this species in the Park.

Amphibian egg mass surveys proved to be logistically feasible and educational for park volunteers. Results revealed that Northwestern salamanders bred in ditch and wetland areas of the Park in 1998. Egg masses were observed in February, March, and April. The accumulation of amphibian egg mass survey data over several years may reveal additional information regarding the weather conditions triggering Northwestern salamander breeding at Colony Farm Regional Park and the validity of egg mass surveys as a monitoring technique.

Minnow trapping confirmed the presence of Northwestern salamander larvae and paedomorphic individuals in ditch and wetland areas of the Park. Statistical evaluation of the 1998 minnow trapping results using Monitor software (Gibbs 1995) revealed that the methodology used did not provide the desired power to detect positive or negative trends in Northwestern salamander populations over time. It is recommended that the investigation into suitable monitoring techniques for Colony Farm amphibian populations be continued.


In future formal egg mass surveys could be conducted once a month during the expected breeding period to provide results that could be evaluated for ability or predicted ability to detect trends. Performing amphibian egg mass surveys on a more frequent basis may also allow for a more accurate prediction of temperature thresholds and amount of rainfall required for Northwestern salamander breeding.

It is recommended that the investigation into suitable monitoring techniques for Colony Farm Regional Park Northwestern salamander populations be continued.

Minnow trapping results revealed a relative high abundance of amphibians in the Sheep Paddocks wetland area. The observed evaporation of water in this area suggested that amphibian larvae inhabiting this area did not survive past August 1998. Possible wetland enhancement activities such as increasing the depth of water in the area using soil removal and/or the installation of culverts could help to maintain water levels in the future.