Nesting success and population status of the 'Elepaio (Chasiempis sandwichensis) in the Mauna Loa Strip section of Hawai'i Volcanoes National Park

Abstract

We investigated the nesting success of 'Elepaio (Chasiempis sandwichensis), in a 17 ha study grid located in the Mauna Loa Strip section of Hawai'i Volcanoes National Park during 1993 and 1994 breeding seasons. 'Elepaio nests were most typically found in 'a'ali'i (Dodonaea viscosa) trees in our study area even though this species was less abundant then the other co-dominant tree species koa (Acacia koa). Nest success was 26 of 44 (59%, n=27 pairs) in 1993 and 20 of 72 (28%, n=31 pairs) in 1994. Predation by black/roof rats and feral cats was the most prevalent reason for nest failure, accounting for 34% of failures in 1993, and 57% of failures in 1994. We found 'Elepaio renested after either a nesting failure or successful attempt. In 1993, 'Elepaio renesting attempts peaked at four. However, in 1994 we found 4 pairs that renested six, six, seven and eight times respectively without being successful. Because of their ability to renest after a nest failure, 74% of the 'Elepaio pairs in 1993 were successful in fledging at least one chick from one successful nest during the season. Pair success was 65% during the 1994 nesting season. The ability of 'Elepaio to renest repeatedly suggests double clutching and subsequent reintroduction of captive reared chicks may be a very useful technique to augment declining populations of this species in other areas in Hawai'i. The 'Elepaio population in the Mauna Loa Strip Road study area provides an excellent opportunity to evaluate the effects of different levels of predator control relative to the bird's nesting success.