The saddle-billed stork photographic survey that took place in the Kruger National Park (KNP) from September 2009 to September 2010 has been concluded. Competition winners have been announced and preliminary survey results for the southern sections of the Park indicate a total of 55 birds remaining in this area.
This survey forms part of a research project that is being conducted on the population status of saddle-billed storks (Ephippiorhynchus senegalensis) from 2009 to 2011. The birds can be individually recognised by the details on the black band across the red bill.
Side-on photographs of the birds, from both the left and right angles, were used in identification during the survey. Over 5 000 photographs were received from 2 000 entrants although only submissions with clearly identifiable bill markings could be used for data analysis and 62 percent were rejected.
A panel of judges evaluated the contributions in three categories: portrait, action category and best overall contribution. The winner in the portrait category was Keith Marallich, who submitted two mugshots of a male stork photographed on 9 March 2010 just south of the Sweni Bird Hide. His prize is a pair of Pentax 10x43 DCF SP binoculars, sponsored by Pentax.
The action category was won by Kobus Brink, who was also a finalist in the portrait category. His winning photograph was taken on 18 May 2010 on the gravel road travelling east and following the N'wanetsi Spruit from Satara Camp. His prize is a two night stay for two people sharing at the luxurious Tinga Private Game Lodge on the banks of the Sabie River.
The best overall contribution was submitted by Brent Smith and Samantha Meeke, who submitted no less than 11 entries, including a sub-adult stork range. Their prize is two nights for two people sharing at Kings Camp Private Game Reserve.
Preliminary survey results indicate a minimum number of 40 adult saddle-billed storks in the southern sections of Kruger.
The bill markings only become distinctive when storks reach adulthood and as such juveniles and sub-adults are analysed based on geographic locations only, and an additional 10 juveniles and five sub-adults were counted using this method. Complete survey results for the rest of the Park will be made public as they become available.
The photographic survey method relies on contributions from the public and as such, contributions received after the study period may affect population estimates when using statistical models.
However, an advantage of this survey method is that the birds do not have to be physically captured and handled, and continuous population surveys are possible. The vastness of the KNP combined with the inaccessibility of some areas makes a total population count of this species almost unachievable.
As such, the aim is to determine a population index and with repeated measures of the index over time, the population size can be monitored. Monitoring with an index is cost-effective and efficient.
Saddle-billed storks are classified as endangered in South Africa. They breed slowly and are dependant on extensive wetland habitats, which are under increasing pressure from developments.
The flow regimes of rivers passing through the Kruger National Park are expected to change in response to catchment developments outside the Park, and this, together with the removal of artificial water impoundments within the Park, may have a negative impact on this species.
In South Africa, saddle-billed storks are largely confined to the north-eastern tropical lowland with the majority of the population residing along the riverine habitat in Kruger. They normally occur in pairs, are strongly territorial and remain in the same area for years.