The Annual Migration – Part III

Posted on February 21, 2012

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(Part III of a three part series)

 

“If whitetails occasionally experience ‘psychological highs’ – and I think they probably do – one such high time for northern subspecies must be during the spring break-up, when snow finally melts and gives way to fresh sprouts of nutritious herbaceous forage.”

                                                                                                                                                                        –          John Ozoga   

 

For you that have never walked atop a compacted maze of interwoven deer trails, littered with deer droppings in various forms of decay found amidst dense growths of cedar and balsam, or experienced what life would be like eating the same meal day after day in seclusion to only the pathways established early on in the winter, all the while making every attempt to refrain from being some predators next meal, welcome to the whitetails world. It is no wonder that when it is time to escape this imprisonment that the animals are more than ready for their freedom, and all that spring life can and will engender.

Spring Break-Up

 

For more than 100 days the whitetail has been held captive under seemingly insurmountable odds, subsisting on a meager diet of coniferous matter. They have undergone the stress of close interaction with others of their kind in tight quarters with less than ideal conditions. If you ever want a sense of what this experience may be like –  no I don’t advocate checking yourself into a prison – take an international flight that lasts for 18 hours or more and is completely booked. Trust me, this experience becomes a real eye opener as to what whitetails must endure for nearly four months under some of the most severe conditions imaginable.

 

Throughout the winter months the deer’s metabolic rate has been severely reduced, allowing the animal to be conservative with its food intake. Because so much energy is required to compensate for heat loss, most deer are on a negative energy balance by winters end. According to Ozoga, “The whitetail’s otherwise impressive strategy for winter survival weakens around mid-March, when its metabolism shifts back to a higher level. The response to increasing daylight accelerates energy, or food demands. Fawns from the previous year resume their growth, and the fetuses of pregnant does advance in their development. These changes rapidly sap the animal’s remaining energy reserves. Depending on temperature, snow depth and the rate of snow melt, deer sometimes experience hazardous and exhausting travel at spring break-up, making a bad situation worse.”

 

It appears that significantly reduced snow depths are the impetus to begin leaving the confines of a deeryard. As the snow pack recedes under a warming March sun, whitetails begin to make their journey back to summer range. Because no two winters are the same and it becomes anyone’s guess as to when the snow pack will be reduced enough to facilitate this movement, it remains difficult to predict exactly when this will transpire from one deer yard to the next.  Minnesota biologist Michael Nelson has monitored wintering whitetails in the Central Superior National Forest in northeastern Minnesota for 19 years and found that dispersal from individual yards was as early as March 19th to as late as May 4th. In each instance it seems the depth of snow pack was one of the key elements in releasing the penned deer. Nelson’s researched showed that 80% of the deer had migrated out of the winter yards by the time snow depth reached 10 cm. Once the process has begun, most deer will disperse within a two-week period. The only influence of temperature at this time of the year is on how quickly the snow melts so that the deer can be on their way.

 

The Young Bucks Dispersal

Dispersal refers to a movement away from the original home range and establishment of a more-or-less permanent new home. The catalysts for this dispersal of 1 ½ and even some 2 ½ year-old males is the antagonism displayed by older age class bucks as they compete for breeding privileges, and more importantly, the ‘boot from the house’ they receive from the dam and other closely related does within the family just prior to breeding. In a study done by deer researcher Larry Marchinton, it was learned that it is usually the mothers that drive the young bucks away. After radio tracking 15 male whitetails that had lost their mothers following the weaning process, only one of these orphans was found to have left the birth range. Of nineteen separate bucks with mothers, eighteen had dispersed by the time they were 2 ½ years old.

 

The distance these bucks travel to eventually take up permanent residency varies from animal to animal. Distances between 2 to 6 miles is common, but there has been at least one documented instance where an ear tagged male was found to have traveled 93 miles when he was eventually shot during a firearms season. One of the dangers and consequences of adolescent bucks roaming around looking for new lodging, particularly in the autumn when hunters are out and about, is the fact that he is now in unfamiliar territory. With the equivalent mentality of a twelve year-old boy, this young male stands a greater percentage of meeting his early demise as he encounters roads, fences, and hunters with only his own intellect to now guide him.

Although this dispersal from familiar grounds can be costly to an individual buck, it benefits the rest of the deer population. By dispersing, the young male avoids inbreeding with related does, and fills a void by introducing new genetics to another herd once he reaches maturity.

 

Another factor to consider, should deer populations be low, as they typically are in the north country, and if a young buck is not run off during the fall breeding season, is the make-up of fraternal buck groups within the deer yard. As bucks begin to congregate during the winter months these young bucks establish social bonds with other unrelated males from a different summer range. As a result of this bonding, the young buck may then follow his new comrades back to their home turf once spring break-up occurs.

 

Conclusion

Because there is no set recipe or formula to predict exactly when deer will begin to migrate towards their winter yards, it becomes imperative that hunters study and have an in depth understanding of whitetail movements within their own hunting grounds. Knowing the impetus that triggers this migratory passage – outlined in this three part series as temperature, snow depth, nutritional food supply, cover and traditional habits – can only aid the consummate huntsmen in his quest to gain an advantage.

 

All images on this site are copyright protected and the property of R.G. Bernier

    © 2012 R.G. Bernier Nature Photography – All rights reserved.

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Posted in: Whitetail Deer