In Victorian times, the herd thrived. By 1913, numbers stood at 82. This was the high point of the herd, and chill economic winds prompted a cull down to 60, followed by reductions in the area available to the cattle. Up until the 1940s, numbers were around 40.
Disaster struck in 1947. Practically no hay had been made the previous year, owing to appalling weather, and the winter started in earnest at Chillingham on 22 January. For 60 days the park was snowbound, with some drifts 40 feet deep. At the end of 1946 there were 34 animals; at the end of March 1947, there were just 13 – 5 bulls and 8 cows. It took a while for breeding to resume; no calves were born until the spring of 1949. Numbers climbed back and rose steadily until the late 1970s when there was a period of instability, after which they remained steady at around 40-50 but with a slight decline to 2002. Around then, the size of the sheep flock that shared the park (under a separate grazing tenancy) began to be reduced and the flock was removed altogether in 2005. And now, there are more Chillingham cattle than there have ever been in their recorded history.
It seems clear that the sheep had been competing with the cattle for food, but other factors must have been involved. It is not easy to disentangle these – weather and the number of animals already in the herd are just two of them; they can affect different age groups, and the two sexes, in different ways. For example, global climate change has led to earlier spring flush of grass, which is encouraging the cows to conceive earlier in the year, which is bringing forward calving dates. While this may not be good for survival of newborn calves, the increase in numbers shows that this is not obviously affecting herd numbers as a whole.
It’s important not to be too assertive about what determines numbers in populations of large mammals generally, this is a highly complex subject and is the subject of current research at Chillingham.