Use of Artificial Nest Boxes to Facilitate Egg Collection for an Eastern Hellbender Head-Starting Program

Population declines have been taking place throughout the entire geographic range of the eastern hellbender (Cryptobranchus alleganiensis) in North America. The declines and local extinctions have led to multiple head-starting programs to augment or restore hellbender populations. Once widespread throughout the Susquehanna River basin, the eastern hellbender is now restricted to several tributaries of the West Branch watershed. In order to establish a head-starting program for the Susquehanna River basin, we are collecting fertilized eggs to be transported to zoological facilities that are prepared to raise larval and juvenile hellbenders until they are of a size where they are unlikely to be subject to predation (3-5 years of age). To facilitate the collection of fertilized eggs, we installed 17 artificial nest boxes in the late summer of 2014. The boxes are distributed across three stream reaches occupied by hellbenders and within a single tributary of the West Branch watershed. The boxes are made of concrete and weigh 27 kg. By mid-September, no adult hellbenders had taken up residence in, nor had nested within, the concrete boxes. We now believe that the nest boxes should have been installed several months in advance of the nesting season so that adult hellbenders would have had more opportunities to find the boxes and take up residence. We plan to leave the boxes in place until the next nesting season, but will modify the boxes to darken the chamber, making it more suitable for permanent residency and egg deposition. In lieu of collecting eggs from the artificial nest chambers, we are currently searching for natural nests from which we hope to collect eggs to be transported to the head-start facility

Habitat Preferences, and Population Structure and Stability, in an Eastern Hellbender Population in the West Branch of the Susquehanna River

We collected habitat and population data over two field seasons (2012 and 2014) for an eastern hellbender (Cryptobranchus alleganiensis) population in a tributary of the West Branch of the Susquehanna River. Analyses of population data show that the population has been stable across the sample years, with no significant change in linear density. Analyses of habitat use show that hellbenders take up residency in or near the thalweg, where the majority of cover rocks are located. Peripheral cover rocks are only rarely used by hellbenders. We found a positive relationship between the size (total body length) of hellbenders and the size (length) of the cover rock. Population size/age structure and sex ratios were similar between the two sample years. During the second field season (2014), we observed American eels (Anguilla rostrata) beneath cover rocks, but in no case did we find eels and hellbenders beneath the same cover rock. We observed no eels in the study area in 2012. Recent eel introductions in the watershed likely explain the sudden appearance of eels in the study reach. The precipitous co-occurrence of eels and hellbenders raises the concern that eels may compete with hellbenders for rock cover and for a limited food resource that consists mainly of Allegheny crayfish (Orconectes obscurus). Significant competition for food and cover, and eel predation on hellbender eggs, larvae and juveniles, could potentially initiate a decline in an otherwise stable hellbender population