In Nigeria, prices rise during festivities...
Why?
(no its not greed)
Thus take Turkey, demand goes up in the US in November before Thanksgiving but prices dont rise because the supply of Turkey also increases.
Supply can rise because of supply chain efficiencies
Even imports cannot ameliorate price because of logistics bottlenecks, this demand pressures keep prices up.
Harvest are not all processed and stored all year round. Thus bumber harvests simply fizzle out and supply is not timed to demand.
Agriculture is about technology ans science not hard work