Penrhyn Estuary is the only significant shorebird habitat remaining on the northern side of Botany Bay today. The small estuary was created artificially during the reclamation of the Botany foreshore between 1975 and 1978, and has been utilised by a diverse group of migratory birds. When Port Botany was expanded adjacent to Penrhyn in 2008, Sydney Ports Corporation rehabilitated the estuary, enlarging the size of primary foraging habitat from 2.5 ha to over 16 ha.
To measure the success of habitat enhancement works, the abundance of key species is monitored and compared to target numbers derived from pre-construction data in 2006, as well as counts at reference sites. Six key species were selected to indicate the success of the rehabilitation project: Bar-tailed Godwit, Red-necked Stint, Double-banded Plover, Curlew Sandpiper, Red Knot and Pacific Golden Plover. In this paper, we will discuss our findings from eight years of monitoring, including three years during and three years post construction.
The 2013-2014 peak period, September 2013 to March 2014, marked the first season during which, for the first time since pre-construction records, all six key species were observed in Penrhyn Estuary. However, numbers have dropped in the current peak season, with only four of six key species observed in the 2014-2015 peak period, September 2014 to March 2015. The diversity of migratory species has increased in post-construction years, approaching pre-construction conditions. Some species have met their target count indicating a positive result, while others remain below target or absent from the estuary. Nocturnal surveys have revealed higher numbers of some species, such as the Bar-tailed Godwit, compared to diurnal counts, raising questions about the role of artificial illumination in foraging behaviour and habitat selection. Future research will look at implications for species falling below the target count, and constraints of constructed habitats of this nature.
