As has been done every year since their reintroduction, we attempted to count the population of kākāriki karaka in the Brook Waimārama Sanctuary early this week. Department of Conservation staff drove up from Rangiora, some Nelson City Council staff helped out, and with Brook staff and volunteers it was all hands on deck with approximately 24 people doing the survey. Twelve lines were walked, with parakeet playback audio played through speakers on a rough 200-300m grid. Surveyors listen for responses, then try to lure in any parakeets detected and identify them. The survey was conducted on Sunday, then repeated on Monday (with surveyors changing lines to reduce data-collector bias).
Approximately 150 playback points were used, and this data was added to lower-priority playback data collected over the previous two days in areas with lower expected parakeet density.
So, how many kākāriki karaka did we count? Well, that's a difficult one to answer for a few reasons:-
- The birds showed only modest interest in our playback survey last year; this year they showed even less interest. This means that an unknown number of parakeets will likely remain undetected during the survey. (Of the 42 parakeets detected during 23 playback points on my two lines, I'm only moderately confident that two of them may have reacted to the playback, the rest appeared unresponsive to the playback.) For whatever reason, they aren't interested in the playback. Perhaps they're clever enough to know it doesn't come from 'real' birds. Or perhaps they detect the playback doesn't come from birds resident in the sanctuary (the playback audio was recorded elsewhere). Or perhaps parakeets are now so common in the sanctuary that the sound of parakeets chattering nearby is immaterial to them. Your guess is as good as mine....
- Over the last month or two, it has become clear that the parakeets in the sanctuary are going through a 'quiet' phase. They are there, but not being very vocal. In many cases they are going about their lives in complete silence. Small green birds in the tree canopy the same colour as the leaves become quite a lot harder to detect if they're also silent! What's the explanation for this silence? Nesting has ended (nesting involves communication). Offspring have grown up and become independent (parents with fledglings make quite a bit of noise for a time). There are signs that food is plentiful in the sanctuary, so perhaps the parakeets don't feel the need to inform other birds about the presence of food. Etc. Birds are not performance artists, their vocalisation would tend to be communication of some sort, and if they have nothing to say, then it seems likely to me that they won't say it. Hence their quietness.
- Upon upload of the playback data (the playback points used and any birds detected), the DOC database malfunctioned and some data was not added to the database, users then had some of their data erased from their input devices (their mobile phones). The missing data was subsequently detected but we have been told that it will take some months to add to the database. I do not have access to the missing data.
I am not terribly patient, and chose to not wait for a few months for the missing data. I also know that some of the participants in the survey (and anyone else involved in anything at all at the sanctuary) would like some indication of how the survey went and any indicators to our parakeet population. (I have been asked a few times how many birds we found, and was not sure how to answer.) So I scraped the database for what information was there, used a fudge factor for the missing data, and the biggest fudge factor of all; the likely non-detection rate of our parakeets (i.e., what percentage of our birds did we miss due to their silence and non-response to the survey).
I did come up with a likely population range (that I think our kākāriki karaka population is very likely to lie within), but won't post the numbers here as it's very unofficial - it's only MY numbers - but will say that I'm pretty happy with the number. It is consistent with continued significant year-on-year population growth. It also is consistent with anecdotal information indicating a healthy population. E.g., most of the previously-used nest holes we watched over the summer became active at some stage (some more than once). We confirmed more nests this season than in previous years even though we didn't try as hard (and didn't have the benefit of radio tracking). Parakeets are being detected further west and down the valley. Etc. The closest I'll get to providing my best estimate for the kākāriki karaka population in the Brook Waimārama Sanctuary in writing at this stage would be "a few hundred". Hopefully that will keep everyone happy until the official (and somewhat more scientifically-robust) number becomes available some months from now.
In the meantime here's a mugshot of one of the population I met yesterday.
