In order to maintain or increase a population, a species needs to be able to breed in sufficient numbers to produce enough recruits to replace the older birds that die. These days with many parts of the world infested with introduced predators and imbalances in the ecosystem, as well as unsympathetic agricultural practices, this is no longer possible for many wader species and it is this that is causing modern population declines.
Fewer eggs get to hatch and of those that do very few will fledge. This is of course a perfectly natural state of affairs, not every egg laid is expected to survive to fledging but the required percentages are far from being met and so the population becomes increasingly geriatric which, as they die off, are not being replaced.
Headstarting then is a method of circumnavigating the most vulnerable part of a ground nesting bird’s life from egg to fledging. Eggs are taken from wild nests and hatched in captivity; the chicks are provided with suitable feeding opportunity, protected from predators, and then released once they have fledged.
This is possible due to a number of traits of nesting waders:
- Removing the eggs from a breeding pair early means the adults are likely to lay a second clutch. This second clutch will be left with the adults to take their chances in the wild. Relaying after the loss of eggs is a perfectly natural response but the longer it is delayed after laying, the more energy the parents have invested in them and the probability of replacing them decreases. Once the chicks have hatched birds rarely relay if those chicks are lost.
- Almost all wader chicks are precocial, which means they do not have to be fed and they are able to get about by themselves within hours of hatching. At this stage their parents are there to help them find the best places to feed and to keep an eye out for predators, both of these factors are satisfied by the captive status of the birds.
- Another factor that helps enormously is that migrating waders do not travel in family parties on the whole. Laying eggs takes a lot of energy and females once they have hatched the eggs will often leave the breeding grounds to go to the coast to fatten up ready to migrate. The males have not used up the same energy by laying eggs so stay a little longer to protect and guide the young. Once those chicks are fledged, the male’s work is done and he too will leave for the coast. Young birds are then left to fend for themselves. They will often congregate in large flocks and will eventually leave the breeding grounds themselves, unaided by the adults and somehow still find their way to the stop over and wintering sites. It has been found that headstarted birds do not have any trouble migrating and entering the normal pattern of an adult’s life.
The Spoon-billed Sandpiper is Critically Endangered and is teetering on the edge of extinction; it was a prime candidate for headstarting. A team comprising a number of organisations has been headstarting Spoon-billed Sandpipers in Russia. Some of the headstarted birds have returned to breed themselves. One story of a pair demonstrates the value of this method of bolstering recruitment. Upon losing their eggs to the headstarting team the pair re-laid and managed, against fearsome odds, to fledge all four chicks, a tremendous achievement in itself. Meanwhile the headstarting team did the same with the eggs they had removed from the pair’s first attempt, resulting in eight recruits to the population from one pair that year. The headstarting programme in Russia has resulted in over 100 new recruits entering the population, very few of which may have done so if left in the wild, in addition at least some of the replacement clutches will have fledged some young birds.
In the UK the Black-tailed Godwit has had a poor run of things. Previously it would have been common as a breeding bird in the fens. It was hunted for its flesh which is reputed to have been very good, but this subsistence hunting would probably not have affected the population too much. However the wholesale drainage of the fens did, and as the fens disappeared so did the breeding habitat of the Godwits which became rarer and rarer. As they became rarer, unfortunately for them, they did so in an era when collecting was rife. Owning the skin of a British Black-tailed Godwit and/or its eggs became increasingly desirable. The rarer they became the more desirable they were. Eventually the last known breeding pair and their eggs were collected in 1885. In the 1930s they reappeared and started breeding regularly in very small numbers on the Ouse Washes in 1952. Now a joint venture between the RSPB and WWT in the region is working to enhance the population by headstarting breeding Godwits in East Anglia. So far the signs have been good, the captive birds fledged and were released in 2017 and were seen feeding around the release site. Eventually they left to migrate and although the project was not expecting them to return until 2019, as they normally breed in their second year, six birds did return and some of those even showed signs of breeding. How many of the remaining birds return remains to be seen.
It may seem cruel to deprive a nesting bird of its eggs, but in the long run, as we have seen, it has a positive effect on the population as a whole and it is surely better than losing a bird to extinction because we sat back and did nothing. Wildlife faces a very uneven playing field in the modern world, so surely our moral responsibility is to do everything within our power to even the odds a little.