Many natural wetlands have been converted to human-influenced wetlands. In some instances, human-influenced wetlands could provide complementary habitats for waterbirds, compensating for the loss of natural wetlands. Inner Deep Bay in Hong Kong is composed of both natural and human-influenced wetlands and is under immense development pressure. From an ecology perspective, we need to understand if different wetland types play the same ecological role. To achieve this, we tracked nine little egrets (Egretta garzetta) using GPS loggers for 14 months to study their spatial ecology, home range, movement and habitat use. We found that over 88% of the home range of all individuals comprised of wetlands (commercial fishponds, mangrove, gei wai, channel, and intertidal mudflat). Among these wetland types, nearly all (seven of nine) individuals preferred commercial fishponds over other habitats in all seasons. Little egrets exhibited seasonal movement and habitat use among seasons, with largest home range, greatest movement, and most frequent visits to commercial fishponds in winter compared to spring and autumn. Our results highlight the significant role of commercial fishponds, providing a feeding ground for little egrets. However, other wetland types cannot be ignored, as they were also used considerably. These findings underscore the importance of maintaining a diversity of wetland types as alternative foraging and breeding habitats.
Bibliographical noteAnimal Ethics
The following information was supplied relating to ethical approvals (i.e., approving body and any reference numbers): Agriculture, Fisheries and Conservation Department of the Government of the Hong Kong SAR, China provided approval for this research [(43) AF GR CON 09/51 Pt. 6, (99) AF GR CON 09/51 Pt. 6, (166) AF GR CON 09/51 Pt. 6, (79) AF GR CON 09/51 Pt. 7].
Field Study Permissions
The following information was supplied relating to field study approvals (i.e., approving body and any reference numbers):
All procedures were approved by the Agricultural Fisheries and Conservation
Department of the Hong Kong Government [permit number: (43) AF GR CON 09/51 Pt. 6, (99) AF GR CON 09/51 Pt. 6, (166) AF GR CON 09/51 Pt. 6, (79) AF GR CON 09/51 Pt. 7].
The following information was supplied regarding data availability:
The raw GPS relocations of the nine tracked little egrets are available in the Supplementary Files.
Supplemental information for this article can be found online at http://dx.doi.org/10.7717/peerj.9893#supplemental-information
This study was funded by the Environment and Conservation Fund of the Government of the Hong Kong SAR, China (No. EP 86/19/271). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
- GPS tracking
- Habitat use
- Home range
- Sustainable land-use management
- Wetland conservation