In the Outdoors: When the chase is on

Whitetail deer begin breeding season with a lot of running

By Oak Duke

     We call it the pre-rut.

     And it’s coming right up.

     The third week of October this year.

     Many of us deer hunters wait, plan, dream, and pine for this time.

     But sometimes tragically, car/deer accidents also peak then too.

     Why?

     Seems simple.

     Bucks chase does for the most obvious of reasons, right?

     Duh.

     But as in most things in nature, once we peel back the layers of the onion, things become more complex than first imagined.

     This time of chasing, the prelude to actual breeding, is a behavior replicated through other critters, not just by deer, by other Ungulates, or hoofed animals, such as sheep and goats.

     Chasing…that is when bucks run after does, or Billy goats chase nannies, or rams run after ewes is a necessary precursor to the actual breeding time.

     Chasing is not the breeding time.

     But it’s necessary for the breeding time to occur.

     Lockdown is a term deer hunters have coined as the phase of the rut when does are actually bred and conception starts.

     And it is usually two- to three weeks after the chasing.

     Then why such emphasis on chasing at all, since its really weeks ahead of whitetail breeding?

     And haven’t instances been observed where bucks run after does early and breeding does occur at that time?

The “Ram Effect.”

     Shepherds and goatherds from biblical days have introduced what’s called a “novel” Ram or young Billy goat to their breeding flocks to stimulate estrus in their female animals by… chasing.

Just a tease.

     Some ungulates have evolved a different breeding pattern or behavior than many other animals, one timed so newborns will all land on terra firma at the same time, 200 days hence, the gestation period for deer.

     Fawns, all being born at the same time is not only beneficial, but crucial for a number of reasons.

1. For one thing, predators are overwhelmed with the flush of fawns all being born simultaneously.

The market is flooded.

Predators: Black bears, coyotes, eagles can’t eat them all.

Very soon, the little fawns that won the predator/prey lottery outrun their foes.

2. Secondly, in the northern latitudes, there is an optimal, albeit narrow birthing window of opportunity for maximizing survival.

     Born too soon, and the cold winds of April, mostly north of roughly 40 degrees latitude, threatens death for tiny wet newborns.

And besides, lush grasses, buds, and forbs, so critical for optimal fawn feed have not adequately regenerated in early springtime.

     Not so important in the south where the birthing window’s timing can and is in fact much wider. And in the tropics, deer breed year round. 

The further south one goes, generally down below the 35th latitude, the timing of the rut is more spread out, not so intense as experienced in the northern parts of the country.

     And it follows that northern fawns thrive best if they are not born too late, thereby being too small to survive an early, brutal winter.

     When man domesticated sheep and goats, the natural chase phase could be replicated when they desired, on man’s timetable.

     Lambs and kids could be born at the same time, on the farmer’s schedule, by introducing a novel teaser ram, often young and sometimes castrated…just in case.

     The internal biomechanics is interesting and applicable to whitetails.

     Glandular secretions, hormones and pheromones, from rams, billies, and of course bucks stimulate females to ovulate as they come into their breeding window of time.

     Short-day breeders synchronize and react to photoperiodism, the amount of sun and moonlight (reflected sunlight.)

     For the ram effect to work optimally, billy goats and rams should be isolated and removed from the females for a period of time, at least a couple months, on farms by fences and other locations, but in the wild in an analogous case… whitetails… bucks being naturally isolated in their bachelor groups and does in their respective family units.

     Modern technology has assisted man with CIDRs… (Controlled Intervaginal Drug Release) progesterone saturated suppositories for deer farmers; cattle, sheep, goats and other ranchers to do the same thing.

     As the narrow northern breeding window opens in October, bucks begin scraping, and signpost rubbing.

     Their tarsal glands and others become quickly darker and stinky, oozing hormones and pheromones. These testosterone-driven processes bio-stimulate does, naturally.

     As does visit scrape sites and signpost rubs, they hook up with bucks where they are chased and get necessary non-olfactory stimulation too.

These early Chase phase stimulations produce what is termed the silent ovulation as does are not ready, in most cases, to stand for bucks.

     But the important thing is…the egg, or the follicle begins its two-, to three-week path down the chute from the synergistic bio-stimulation of chasing (the Ram Effect) in whitetails.  

     So, say that we experience bucks (mostly youngsters) grunting and chasing does in late October, acting just like teaser rams with ewes.

Then, we can expect Lockdown, or when does will actually accept bucks, stand for bucks, a couple weeks later in mid-November.

     There is really not much chasing going on in the north once actual breeding starts. Some sure, because the rut is a Bell curve in time.

     Again, the timing window for northern whitetails closes quickly so that fawns can be born at the optimal time, generally in late May and early June.

     All that chasing going on each year, and its relatively precise timing, is a crucial part of the process of the rut, but not the breeding time for the most part.