Doing control work for many years I learned that for me and in my area the biggest reason that animals killed large numbers of live stock were ,1 they had young to feed , 2 they were old and livestock young were easy meals , and a few just took the easy way to make a living . In late April normally around the 25th is when I would start to look for coyote dens as well as red fox dens . I found a red fox den once on March 3rd and a coyote den on the 12th of April but they weren't the norm . With the coyote my records show that the older coyote had pups earlier then the younger females and that made sense to me as the weather is better , there are more animals for feeding the pups latter in spring . With coyote both the male and female , and often a young from last year will help with raising the pups , while with red fox it's most often that the female is the one who raises the pups on her own . Coyote tend to keep their dens cleaner then red fox and often you can smell a fox den from some distance . At fox dens I've found all kinds of rotting animal parts , birds , snakes , mice and lamb parts are common at them . Early on you will often find lambs that have had just the soft tissues eaten and the rest left ,as they will eat the soft parts then carry it back in their stomachs to regurgitate for the young pups like we feed baby foods for our small ones . With fox latter on you will often see lambs with most or half of their tails missing as that is what the fox will be able to grab as the lambs run from them and it will get pulled off . With bob cats you usually will just notice that there are fewer lambs now then there should be as like a lot of the other cats they will carry off the lambs to eat in a secluded place till the lambs get bigger then you will find that the lambs are drug to a low spot . Studies done by others have shown that with coyote you need to take some where around 75 percent of the years young to just maintain the same numbers . So what I have learned over the years is that starting in Feb. if I target the female coyote and then do denning to keep the number of young down that the coyote tend to leave the livestock alone better . And by doing this I was able to get larger lamb number to market in the fall for the producers and I still never had a shortage of coyote or fox but found that you can easily kill out the numbers of bob cats in an area . It's all up to each to figure out what works for them in their area and time doing it will teach them more , hopefully , about their needs and keep them from having problems along the way to learning what works for them .