Baby steps forward
(This article was originally published in The Horn, autumn 2016. Author: Natasha Anderson, Rhino Monitoring Coordinator, Lowveld Rhino Trust)
In this time of escalating poaching, a lot of attention is paid to statistics. Every loss is a hard blow. Not only because we are dealing with species’ threatened with extinction, and every poaching death is a step backwards; but also because, often, we are losing an animal we have known for many years. They are not just a number in our population tally but are an individual with personality and a shared history.
In early August, Lindiwe and her calf became victims to the poaching onslaught. Statistically, Lindiwe was rhino identification number 2079; a 25-year-old black rhino cow. Statistically, her calf was her sixth confirmed in Bubye Valley Conservancy. Together they represented 0.9% of the Bubye Valley black rhino population. Personally, she was an inquisitive and gentle rhino I first met 13 years ago when the Lowveld Rhino Trust (LRT) rescued her with a deeply embedded snare to her left hind leg, leaving a scar that enabled me to identify her carcass after poachers had removed her horns and scavengers removed her ears.
LRT works to monitor and support large (>100) black rhino populations in the South East Lowveld of Zimbabwe. This focus is based on the belief that that strong breeding performance is key to the recovery of this species, and that as a socially subtle and complex species, black rhinos breed best when they can maintain stable social associations. This is achieved when dispersed populations live across large areas.
Various indicators are considered benchmarks for black rhino breeding performance. Seven years old is considered a normal age for a rhino’s first calving. Six and a half is considered good. The average for Bubye and Save combined is six years four months (n=86). Separating this indicator into three groups further illustrates the importance of stable, social environments for black rhinos. If we look at:
- Females that have been translocated
- Females translocated when they were themselves a dependent calf
- Or female not translocated
then we see that the average age at first calf for translocated females in these populations is seven years four months (n=19). For females moved when dependent calves (so their mothers provided social stability) or not translocated, the average age at first calf is six years one month (n=67). For a Critically Endangered species, one extra calf per female is a very valuable contribution.
What is known as an “inter-calving interval”, or the period between giving birth and carrying a new calf, is another important indicator of breeding health. The gestation period for black rhinos is 15 months. A normal inter-calving interval is considered to be 36 months with 30 months being considered good. In the populations monitored by the LRT, the average inter-calving interval has been 29.3 months (n=298), with intervals as short as 15 months being recorded.
Splitting this data in two, based on births to females that have been recently translocated (but not pregnant on translocation) and births to settled females, we see further evidence to support the value of minimising social disruption.
The average inter-calving interval for recently translocated females has been 35.9 months (n=28); for settled females, 28.6 months (n=270). These shorter inter-calving intervals can add up to multiple additional calves born over the lifetime of a breeding female.
The Lowveld Rhino Trust’s rhinos have produced total of 444 black rhino calves – lots of valuable little steps forward in this race from extinction. Poachers, however, have claimed the lives of 230 black rhinos from these populations; taking one step backwards for every two calves that have moved the species forward. But forwards we move. Even if it is sadly without Lindiwe, the future will be with her calves, and their calves.
Since November 2015, we have sent $45,000 from Anna Merz Rhino Trust, £6,536 from Knowsley Safari Park and £502 from miscellaneous donation towards ongoing rhino monitoring costs, and €11,248 from Dublin Zoo for payments to informants. Our UK government Darwin Initiative grant from DFiD for the “Land harmonisation” project we wrote about in the last issue of The Horn commences in October 2016.