Spatial and temporal patterns in the diet of New Zealand king shag
Introduction
This is the final report for one component of BCBC2020-05: Understanding potential interactions and indirect effects between commercial fisheries and New Zealand king shag foraging activity, diets and population trends. Published 2021.Download the publication
BCBC2020-05: Spatial and temporal patterns in the diet of New Zealand king shag (PDF, 1,207 K)
Summary
The New Zealand king shag (Leucocarbo carunculatus) is an endemic seabird that only inhabits coastal areas around the outer parts of the Marlborough Sounds and is classed as nationally endangered. The diet of this rare seabird is of interest because it has been suggested that human activities, such as marine farming operations and forestry activities, may displace or compromise foraging habitat that could affect the population of New Zealand king shag.
A previous study undertaken in 2020 developed advanced DNA methods for identifying dietary items in the faeces and regurgitated pellets from king shag. A comparison of these methods with traditional microscopic identification of hard parts from the diet indicated a relatively high degree of commonality between the two methods.
This current study applied the DNA methods to a further sample of 342 regurgitated pellets, extending the sampling to seven colonies of king shag, as well as the seasonal coverage of the sampling. As for the previous study, fish were the dominant item found in 333 of the 336 pellets that could be analysed, identifying a total of 53 fish species. Witch, crested flounder and opalfish were the three most commonly found species being found in 67, 49 and 46% of pellets, respectively. All three species are not harvested recreationally or commercially, however, other species that were important contributors to the diet, such as southern lemon sole, are harvested by human fishing.
A number of variables were found to influence the composition of the regurgitated pellets including, colony, sex of the bird, and season. These differences in diet may be useful indicators for variation in the patterns of feeding or food availability that may warrant further investigation.
Overall, the results suggest king shags are opportunistic generalist predators that include a wide diversity of fish species in their diet, but preferentially target benthic fish species.