Below are all available counts for Half Moon Island. Explore the interactive chart or search the data table
| Species | Count | Type | Day | Month | Year | Season | Method | Citation |
|---|---|---|---|---|---|---|---|---|
| CHPE | 6000 | adults | 10 | 2 | 1987 | 1986 | offshore vessel | |
| CHPE | 2500 | nests | N/A | N/A | 1987 | 1987 | None | |
| CHPE | 1747 | nests | N/A | 1 | 1991 | 1990 | ground | |
| CHPE | 3342 | nests | N/A | N/A | 1996 | 1996 | ground | |
| CHPE | 3312 | nests | 26 | 11 | 1998 | 1998 | ground | |
| CHPE | 1630 | nests | 5 | 1 | 2008 | 2007 | ground | |
| CHPE | 1732 | nests | 14 | 12 | 2007 | 2007 | ground | |
| CHPE | 2263 | chicks | 17 | 1 | 2009 | 2008 | ground | |
| CHPE | 2023 | nests | 18 | 12 | 2008 | 2008 | ground | |
| CHPE | 2574 | chicks | 29 | 1 | 2011 | 2010 | ground | |
| CHPE | 2036 | nests | 21 | 12 | 2010 | 2010 | ground | |
| CHPE | 1046 | chicks | 19 | 2 | 2011 | 2010 | ground | |
| CHPE | 1849 | nests | 11 | 11 | 2011 | 2011 | ground | |
| CHPE | 2161 | nests | 2 | 12 | 2011 | 2011 | ground | |
| CHPE | 1738 | nests | 25 | 12 | 2011 | 2011 | ground | |
| CHPE | 1836 | nests | 3 | 1 | 2013 | 2012 | ground | |
| CHPE | 1928 | nests | 15 | 12 | 2012 | 2012 | ground | |
| CHPE | 2094 | nests | 25 | 12 | 2012 | 2012 | ground | |
| CHPE | 1818 | nests | 15 | 12 | 2013 | 2013 | ground | |
| CHPE | 1874 | nests | 10 | 1 | 2015 | 2014 | ground | |
| CHPE | 1696 | chicks | 24 | 1 | 2015 | 2014 | ground | |
| CHPE | 1937 | nests | 15 | 12 | 2014 | 2014 | ground | |
| CHPE | 1723 | nests | 13 | 1 | 2016 | 2015 | ground | |
| CHPE | 1968 | nests | 18 | 1 | 2016 | 2015 | ground | |
| CHPE | 1915 | nests | 19 | 11 | 2015 | 2015 | ground | |
| CHPE | 2129 | nests | 7 | 12 | 2015 | 2015 | ground | |
| CHPE | 2097 | nests | 17 | 12 | 2015 | 2015 | ground | |
| CHPE | 1972 | nests | 1 | 1 | 2017 | 2016 | ground | |
| CHPE | 1856 | nests | 9 | 1 | 2017 | 2016 | ground | |
| CHPE | 2749 | chicks | 21 | 1 | 2017 | 2016 | ground | |
| CHPE | 1903 | nests | 3 | 12 | 2016 | 2016 | ground | |
| CHPE | 1216 | nests | 13 | 1 | 2019 | 2018 | ground | |
| CHPE | 1170 | nests | 12 | 12 | 2019 | 2019 | ground | |
| CHPE | 1532 | nests | 21 | 12 | 2019 | 2019 | ground | |
| CHPE | 1298 | nests | 21 | 12 | 2019 | 2019 | ground | |
| CHPE | 1119 | chicks | 12 | 2 | 2022 | 2021 | ground | |
| CHPE | 1083 | nests | 4 | 1 | 2023 | 2022 | ground | |
| CHPE | 922 | nests | 22 | 11 | 2022 | 2022 | ground | |
| CHPE | 1240 | nests | 4 | 1 | 2024 | 2023 | ground | |
| CHPE | 1067 | nests | 7 | 1 | 2024 | 2023 | ground | |
| CHPE | 1230 | nests | 7 | 1 | 2024 | 2023 | uav | |
| CHPE | 1067 | nests | 7 | 1 | 2024 | 2023 | ground | |
| CHPE | 1263 | nests | 13 | 12 | 2023 | 2023 | ground | |
| CHPE | 1201 | nests | 22 | 12 | 2023 | 2023 | ground | |
| CHPE | 1201 | nests | 22 | 12 | 2023 | 2023 | ground | |
| CHPE | 1393 | chicks | 7 | 2 | 2024 | 2023 | ground | |
| CHPE | 1393 | chicks | 7 | 2 | 2024 | 2023 | ground | |
| CHPE | 1237 | chicks | 21 | 1 | 2025 | 2024 | ground | |
| CHPE | 1053 | nests | 16 | 12 | 2024 | 2024 | ground | |
| MCPE | 1 | adults | 11 | 11 | 2011 | 2011 | ground | |
| MCPE | 2 | adults | 9 | 1 | 2017 | 2016 | ground | |
| MCPE | 2 | adults | 13 | 1 | 2019 | 2018 | ground | |
| MCPE | 1 | adults | 21 | 12 | 2019 | 2019 | ground | |
| MCPE | 1 | adults | 4 | 1 | 2024 | 2023 | ground |