Summer fawn survival numbers are in December 14, 2017 Wisconsin

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Summer fawn survival numbers are in December 14, 2017 Wisconsin, DNR News

... Pregnancy rates and litter size of adult does don’t vary much, but pregnancy rates of juvenile does (does getting bred in their first rut and giving birth around their first birthday) are variable. Also, fawn survival can vary tremendously. How and why these two metrics vary from year to year and place to place is complicated and interesting. In future articles, we’ll dig into the many facets of deer recruitment, but for now let’s check back in with the fawns we collared last spring.

We collared 91 fawns. Of those, 45 were male and 45 were female. (The sex of one fawn was not recorded.) We collared our first fawn on May 16 and the last on June 14. May 29 was our biggest day with 13 fawns collared. They weighed in at an average of 10.5 pounds. The largest and smallest fawns were both bucks, and they weighed 18.7 pounds and 4 pounds, respectively...

... So what did we find with our first summer of fawn survival monitoring? Through September, up to 32 of our 91 fawns died. Why do we say ‘up to’? Because sometimes there is uncertainty as to whether the fawn actually died. On eight occasions this summer, only the collar was found with no additional information present to indicate exactly what happened. One time, the collar was found hanging from a barb-wired fence. In this instance, we’re pretty sure the collar got hung up and the fawn wriggled its way out. Other times, it wasn’t so clear – a collar just lying on the ground, no blood, no bite marks on the collar. Did it just slip off? Did the fawn get killed and then the predator (probably a coyote) carry the collar away? Either is possible.

Questions such as these are standard in wildlife survival studies. If we assume that the eight open cases were really mortalities, then 32 fawns died. If we assume none of those died, then 24 fawns died. The reality is probably somewhere in the middle. As we gather more data throughout the study, our analysis will account for these unknown cases.

Here is the breakdown of those we know died: Coyotes are the probable cause of death for 12 of the fawns; bobcats likely took four more. Three died of starvation, and three more died of disease or injury. A domestic dog killed one fawn. The final confirmed death was the result of haying equipment...



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