Northern New Zealand dotterel chick, Point England November 2013.
It’s not what we have now, but we want for the future
Relative to the big bird roosts around New Zealand the roost site at Point England is small. But the majority of birds are at risk or threatened with extinction.
Data extracted from Point England bird observations 2013-2016.pdf
Point England bird (undated) totals 2013-2016
A running total of the maximum number of a given species counted.
These quotes from The House Above the Sea by Ronald Lockley (1980) tell of a time when the Tāmaki Estuary was able to sustain much larger flocks of birds.
Pg 180 “The regiments of SIPO are sometimes a thousand strong.”
and I found this one rather poignant:
Pg 217-218 “To this refuge [ Godwit Island, Tahuna Torea ] now flock hundreds of godwits, knots, torea, stilts, terns, many whitefaced and some reef herons, kingfishers and other birds deposed from the sandspit by strolling humans at high tide. At times the pale mud of Kuaka Island is completely covered with waders. Birds soon learn where they are safe, even where parties of bird-watchers assemble to gape at them across the twenty meters of rippling tide. They are, anyway, full-fed and sleepy and it is too much trouble to move.
‘Of course, ‘ said one pessimistic friend, ‘all that heaped-up mud is bound to slump to its former level. Already it is eroding around the tide-line. What do you propose to do about that?’
‘We, or our bird-loving posterity, will build it up again, of course!’”
We never did.
These quotes from Keith Woodley, Miranda Naturalists’ Trust News Issue 85 explain the importance of having an undisturbed roost site local to a given feeding area.
“A study on the Tagus estuary in Portugal, an important site for Dunlin, looked at bird densities in relation to roost proximity. It found the overall density of birds on suitable mudflat foraging grounds declined with the distance to the nearest roost. … If suitable roosts are lost or degraded, and alternative sites are too far away from feeding areas, the overall carrying capacity of the site will decrease. Why? It is all to do with energy budgets. A shorebird needs energy to meet its daily maintenance needs, and the further it needs to fly to find a suitable high tide roost, the higher its energy expenditure.”
“Sleep for a shorebird is a physiological necessity: it is also the most energy-efficient activity there is.”
"Excessive or prolonged disturbance has severe implications. Models indicate that a relatively small increase in disturbance levels can result in a substantial increase in energy expenditure. Energetic costs to roosting birds may eventually exceed energy requirements for maintenance, moult and pre- migratory fueling. ‘The capacity of shorebirds to compensate for such increases will vary according to the feeding and roosting options available at a site, but it is very likely that circumstances can develop where roost costs could drive the energy budget into deficit.’
The outcome may well be diminished survival or birds abandoning a site completely. Shorebird population dynamics are complex and affected by various factors so it is very difficult to isolate key variables determining population levels and thus quantifying the precise impact of disturbance. Nevertheless, studies in Britain, the Netherlands and in the United States have all linked declines in shorebird populations to disturbance.”