Eighty-four people responded to a survey on this blog. The survey question was: when do you lamb or kid?
This graphic is consistent with the reality that most lambs and kids are born in the first half of year, which results in most being marketed in the second half. This is why prices historically have usually been opposite: highest in the first 6 months; lower in the second half of the year. While other factors can (and do) alter price trends, the fundamentals (supply) still support this historical price cycle. The fact that lambs and kids are sold at different ages and weights, helps to spread out the supply to some extent.