To see the life in a pile of cow dung is to understand how this whole world breaks down. Diving in, the excitement of pursuit can be just enough of a blinder to get past the fact that, you are indeed, digging into a pile of dung.
Scurrying across the pie and poking holes in the dried skin on top, these scarabs are commonly known as dung beetles. They are called dwellers in that they primarily stay inside the cow pie. Whereas, other types of dung beetles can be rollers, which are the ones you most commonly see in a nature documentary. They gather enough dung to roll into a large ball, often times larger than themselves and periodically have to defend it from another dung beetle thief who can steal it after all the hard work put in by the original roller. The third type of dung beetles are called tunnelers and they take the dung down into a tunnel as you might’ve guessed, to brood and raise young dung beetles. The activity this time of year, seems to be greater than what we have ever seen in the last 3 years. Why is this the case? For one, after a couple of years digging in dung, we are better at identifying them, and also because the rain helps bring more life into the pasture increasing the visibility of these incredible insects. But the biggest reason we are seeing more activity is probably because we switched to a planned grazing system that meticulously chooses where the cattle will be on the ranch at given times of the year to provide greater recovery time for the grass plant root systems and ultimately grow more grass and support more life. This form of regenerative management has many benefits including increased forage and biodiversity to reduced pest fly issues by breaking up the life cycle of pest flies. As the intervals are increased by providing more recovery time for the grasses, the larval stage of pest flies tend to die off as a result of waiting too long for their prospective host to return. As a result, we’ve been able to discontinue the use of chemical deworming medications which are detrimental to pest and beneficial insects alike.
Dung beetles and other pasture insects perform tremendous ecosystem services to help grow soil and support biodiversity. They are very good indicators of a healthy pasture. By breaking up the cow pies, they help to deliver nutrients back to the soil by making the dung easier for microbes and micro arthropods to distribute at the soil surface. This allows other insects and invertebrates, like worms, to continue breaking down the dung so that grasses and other plants can germinate or grow through the material. Without this diversity the dung can sit in the field for up 3 years without breaking down. This is not only an early indicator of unhealthy soil, but, if left unchecked, can reduce a rancher’s forage production cow pie by cow pie. This can add up very quickly. Additionally, if manure does not break down, the cattle tend to avoid the areas around it reducing your forage potential, yet again.
By accelerating the decomposition, dung beetles also assist in breaking up the pest fly life cycle. Wet anaerobic conditions are ideal for pest flies to lay their eggs and provide a habitat for fly larva to proliferate. When the cow pie is fragmented, aerated, and dries more readily, the larvae have less of a chance at hatching and becoming not only a nuisance for the cattle, but also a significant cattle disease vector.
We currently know of three different dung beetles on TomKat Ranch. Two are true scarabs and the other is actually a water scavenging beetle that lives in the dung who also happens to also eat pest fly larvae. There may be more, but the group formerly known as Aphodius is the most commonly found in our pastures. Aphodius, which has now been split into many different genera making identification difficult, was likely introduced by European settlers and there are many different species found in the state of California as a result. Most of the activity observed on TomKat Ranch has been during the green months (Dec-June) and they may be seasonal.
This summer, we have a group of interns coming and increasing the number of eyes out in the pasture will help monitor our numbers during the drier months to see if activity declines, and whether or not, other species are present during the warmer months. Perhaps, we’ll have a dung beetle Summer. If we do, we’ll certainly let you know after we and the cattle are done celebrating.