Deer Know How to Handle Flood Events

story by Trey Iles, LDWF Public Information

The sight of a seemingly helpless fawn paints a powerful picture. The photos of fawns being rescued during the August 2016 flood in southeast Louisiana drive home the point that no living being, human or animal, can escape the wrath of weather gone awry.

A cursory look and many might believe that the deer population in the heavily impacted flood areas probably took a serious hit.

No question, higher fawn mortality rates will probably be a consequence of the catastrophic storm that dumped 20 inches or more of rain in some areas. But the overall population of deer fared well in the storm, said Louisiana Department of Wildlife and Fisheries Deer Program Manager Johnathan Bordelon. That’s because deer are resourceful, resilient animals that know how to handle extreme weather events.

“Flooding in general isn’t necessarily going to doom deer,’’ Bordelon said. “Deer are most prolific (in Louisiana) in the flood plain of the Mississippi River, and that’s where our highest harvest actually occurs. Deer themselves cope quite well with flooding. They’re great swimmers. In addition, they often disperse to higher ground as waters rise.

“The adult deer coped pretty well with the (August) flood. Timing and duration were key variables across most of the impacted area. There was a lot of ground that flooded for just two or three days. Then the water receded. So the deer get pushed up, huddled up. But then the water quickly recedes and things are still green. Deer go back to normal pretty quickly and life goes on.’’

Bordelon said fawns less than 30 days of age were the most susceptible to the flood because of their limited mobility. There could have been a large number of that age group in harm’s way because does generally give birth in July and early August in this area of the state.

“Some fawns did succumb to the flood waters,’’ Bordelon said. “Now will it drown the adults? Not likely because it hasn’t in the many years there has been flooding.’’

Louisiana has been hit three times this year by serious floods. The first bout came in January when the Mississippi River exceeded flood stage. Then came the March flood that impacted a good portion of the state. Finally, the August flood devastated many parts of south Louisiana.

In all three events, Bordelon said the deer population made out well but their habitat was negatively impacted. In fact, he said, deer harvest numbers for the 2015-16 season were slightly down in the northeastern parishes, which took the brunt of the January flooding, next to the Mississippi River. Because the deer were driven to higher ground during the January flooding episode, there was an expectation that hunters would have had an easier time harvesting them. But Bordelon said much of the land to where deer escaped was inaccessible to hunters.

“Those deer cope well,’’ Bordelon said. “The worse thing is a lack of resources. Deer can get concentrated in an event like that. That can have a negative impact on deer condition. But what we saw this year were the deer in that area were in pretty good shape despite that. That was encouraging.’’

Deer have proven their resiliency time and again in Louisiana when it comes to flooding.

A research project undertaken by biologists Harry Jacobson, Bronson Strickland, Steve Demarais and Chad Dacus, some of the top deer researchers in the southeast United States, underscores how wily deer can be during a flood. Fourteen collared deer on Davis Island, located in the Mississippi River in Madison Parish and Warren County, Miss., were monitored during a flood in 1983. Twelve of the animals left the island and two remained, both does. The 12 that left had to swim the swollen Mississippi River to safety on the Louisiana side, proving what capable swimmers they are.

One of the 12 that left was harvested by a Louisiana hunter. Once conditions allowed, the other 11 returned to the island. One of the two does that stayed was able to find higher ground and the other died in the flood.

During the 1983 flood, some of the deer moved 10-15 miles from their home range, and one buck was recorded 20 miles away, according to the research.

Bordelon, who has been at LDWF for 17 years, spent his initial 14 years at the department working in the Mississippi Alluvial Valley floodplain, where deer thrive. He said he has always been impressed by the quick return of deer after flood events.

He said deer season success post-flooding was often equal to seasons without flooding. Even after the flood of 2011 when the Morganza Spillway was opened, deer harvest per effort the following season was unaffected on Sherburne Wildlife Management Area (WMA), located along the Morganza Floodway system of the Atchafalaya Basin.

“I ran browse transects two months post green-up (the beginning of the growing season) on Sherburne WMA only to find similar (deer) bite counts similar to the previous pre-flood year,’’ Bordelon said. “The take home for me was the deer not only survived but they were back within two months following green-up. I wasn’t surprised because of what I observed on previous flood events, but it did surprise a lot of people.’’

What concerns Bordelon more than the flooding, however, is lack of quality habitat. Through the last few decades, habitat in southeast Louisiana has declined significantly and taken its toll on deer.

Several factors have caused this, including suburban sprawl into once prime deer habitat, invasive plant species like Chinese tallow and Chinese privet that choke robust deer browse, or food, and the proliferation of feral hogs.

“In southeast Louisiana, we’ve already identified some deer in general where their productivity isn’t what it is in other parts of the state,’’ Bordelon said. “They’re living on more marginal ground. Their nutritional plane is going to dictate their condition and reproductive output. Ground that once would have supported a pretty robust deer herd no longer will. It has everything to do with habitat availability and the plant community.’’

Simply put, some plants are more nutritious than others. Because of several factors, including reduced habitat, there are less of those types of plants.

The flood won’t have the lasting effect on the deer population that declining habitat has. Nevertheless, Bordelon said the department received many calls wondering if deer season should be cancelled in 2016-17 or at least curtailed in the hardest hit areas of the flood. He said he doesn’t expect much of an impact this season.

“Southeast Louisiana is very different from the Mississippi River floodplain,’’ Bordelon said. “Deer came out of this flood pretty well with the exception of fawn mortality in certain parts of the area. Most of that property is privately owned. So hunters are going to have to self-adjust in the hardest hit areas. If they’re not seeing any fawns at all the recommendation would be for them to back off or reduce their antlerless deer harvest in light of the loss of that crop.’’

Impacts to fawns this season will carry over into the 2017-18 season and based on the negative impact to that cohort. Bordelon said LDWF will look at hunter harvest biological data to decide whether or not to make adjustments.

That makes getting information back from hunters this season vital, he said. Deer harvest reporting, which is required under Louisiana law, plays a critical role in setting season lengths and bag limits. If harvest data is underreported, LDWF biologists and managers can’t make accurate determinations on hunting success and deer population parameters.

Prior to hunting deer, all deer hunters, regardless of age or license status, must obtain deer tags and have tags in possession when hunting deer. Immediately upon harvesting a deer, the hunter must tag the deer with the appropriate license tag before moving it moved from the site. The hunter must document the harvest on the attached report card portion of the deer tag license.

“The data we receive is tremendous,’’ Bordelon said. “People are critical of tagging because it’s sometimes cumbersome and they feel like not everyone is complying. So if not everyone is complying then why should I. But, to me as a biologist, it provides a large sample size of data. And that information is key for us to properly manage the deer herds in all parts of the state. We can for the first time accurately track the percentage of males and females harvested per parish. In addition, we are able to track the number of successful hunters reporting their harvest by parish and deer area. When you tag, you’re part of the process of improving the deer population in the state.’’

Consider it a way to aid in flood recovery for the state’s wildlife.





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