Funding for this research was provid-ed by the Mississippi Department - PDF document

Funding for this research was provid-ed by the Mississippi Department ofWildlife, Fisheries and Parks throughFederal Aid in Wildlife RestorationFunds, the National Wild TurkeyFederation (NWTF), the MississippiChapter of NWTF. the MississippiForest and Wildlife Research Centerand the U.S. Forest Service. We oper-ated under the Mississippi StateUniversity Animal Care and UseCommittee (IACUC) Protocol 93-030. Our study was conducted on the 14,410 ha (35,500 ac) Tallahala Wildlife Management Area (TWMA) locatedwithin the Bienville National Forest in centralMississippi. Most (95%) of TWMA was forested with30% in mature bottomland hardwood forests, 37% inmature pine forests, 17% in mature mixed pine-hard-wood forests (30-70% pine), and II% in I - I4 year oldloblolly pine plantations. TWMA was open to the public forspring (approximately March I8 - May I) gobbler-only huntingduring the entire study period. We conducted gobbling callcounts between IO March - 7 May, beginning 7 days before springhunting season and ending 7 days after, from 1984-95. We con-ducted call counts 3 days/week from 2 routes composed of 8and IO stations, respectively, from 30 minutes before sunrise to30 minutes after. We located stations along roads throughoutTWMA at 0.5 mile intervals. Observers listened 4 minutes/sta-tion and recorded number of individual gobblers and number ofcalls heard. Call counts were postponed until the next suitableday when wind exceeded 5 miles/hr or it was raining.We captured wild turkeys at sites baited with corn using cannonnets or drugged bait from 7 January to 4 March and I July toAugust, 1984-95. Captured turkeys received numbered metalbands and wing tags for future identification.We fitted mosthens with an 108 g radio-transmitter placed on the hen so thatit rested between her wings like abackpack. Using the radiosignal, we located hens using a radio-receiver. Beginning 14 March of each�year, we located hens I time/day todetermine when hens began to con-tinuously incubate a nest.Turkey hunters on TWMA wererequired to pick-up, fill out, anddeposit daily visitor permits in self-service check stations. We estimatedhunter numbers (number ofhunters/day) from these permit cards.Successful hunters were required tocheck-in harvested gobblers at TWMA headquarters. From these gobblers,we determined dates when gobblerswere harvested. We recorded mortal-ity dates of radio-ragged hens illegallykilled during spring gobbler-only sea-sonChronology for variables associatedgobbling (number ofgobblers/day, number of hens incubat- ing/day, number of hunters/day. etc.) was standardized as number of daysfrom I March that each event (e.g.. a gobbler harvested, a henbegan incubation, a sportsperson hunted) occurred. From this,we obtained a daily frequency of occurrence for each variablebeginning I March and ending 28 May (Fig. 2). The ending datewas the last nest initiation which represented the last daily eventrecorded. This time period encompassed the spring gobblers-only hunting season. We wanted to determine if events (e.g..turkey harvested, hen initiated incubation, etc.) were similarlydistributed. In other words, were turkeys gobbling the mostwhen hens were on the nest? Or, were hunters in the woodswhen hens were incubating! To answer these questions, wecompared the distribution of events to see if they coincided.We also wanted to determine what factors affected gobbling.We tested a number of environmental (e.g., weather) and biolog-ical (e.g., population size) factors to examine within year andamong year gobbling variation. We used an index of gobbler agestructure (proportion of I-, 2-, and 3- year-olds in the popula-tion) to examine effect of age structure on gobbling activity.Because gobblers have high survival rates on TWMA. it is rea-sonable to assume that higher nest success from 2 years previ-ous, for example, would increase relative number of 2-year-olds in the population. During the I2 years we monitored gobbling activity. weheard I,93I gobbles from 627 gobblers. The most gob-blers heard was I25 in 1986:this year also had the mostgobbles recorded (399).Average number of gobblersheard/day declined from 5.7during I984 to I..2 duringI990 to 0.23 during 1995.Gobbling activity peaked dur- ing I986 and 1994: despitethese peaks, a downwardtrend was evident in gobbling activity. On TWMA, peaks of gobbling and ini-tiation of incubation did not coincideexcept during 1995, making it impos-sible to design a hunting seasonframework to both optimize opportu-nities to hear gobblers and protecthens by opening the season duringpeak incubation (Fig. 2). Currentregulations in Mississippi dictatespring gobbler season to open theSaturday nearest March 20. Movingopening day until mid-April wouldseverely limit opportunities to harvestvocal birds on TWMA.Additionally, contrary to results from other studies, we observedonly I peak of gobbling on TWMA. Accepting the assumption of2 gobbling peaks and structuring spring gobbler season aroundthis assumption may be erroneous. Many researchers/resourcemanagers may assume they can simultaneously protect wildturkey hens and afford hunters maximum harvest opportunity. Areexamination of this assumption is warranted to determineoccurrence and chronology of gobbling peaks and their relation-ship to nesting hens. This work is important to best managewild turkeys, especially on public hunting areas.Within the Southeast, the first peak of gobbling has been associ-ated with break-up of winter hen flocks. On TWMA. winter henflocks gradually broke up during mid-late March. In all yearsexcept 1988-89, 1993, and 1994, the observed peak of gobblingoccurred during this time, suggesting that the gobbling peak onTWMA may coincide with break-up of winter hen flocks.However, inconsistency among years indicates additional factorsmay be involved.We hypothesize that 2 additional factors may influence theobserved peak of gobbling on TWMA. In Ohio, peak of matingwas 2 - 3 weeks after onset of gobbling activity. This possiblepeak of mating also may influence observed gobbling patterns onTWMA. We propose that increased mating activity may stimu-late gobblers to attract as manymates as possible during hens’ peakreceptivity to displaying males andsubsequent copulation. Secondly,peak gobbling may be influenced byinitiation of laying behavior, not incu-bation behavior. Hens requireapproximately 2 weeks to lay a clutchof eggs. Based on our data, hensbegan laying close to the time of peakgobbling. Movement of hens awayfrom gobblers during this period maystimulate males to gobble more fre- quently. Distribution of hunter numbers andharvest differed from distribution ofinitiation of incubation in all years.Hens were not incubating when thehighest numbers of hunters were pre-sent on TWMA. possibly causing hensto be more vulnerable to illegal kill.Although most hens (3 of 5) knownto be poached were killed within thefirst 2 weeks of the hunting season,this is based on a small sample.However, some general conclusionscan be proposed. The highest densityof hunters occurred on lWMA duringfirst 2 weeks of the hunting season (Fig. 2). In Missouri, hunter density, among other factors. may have governed occur- rence of illegal hen kill more than timing of incubation. Illegal hen kill during spring gobbler season may be affected by a higher density of hunters during the first part of a turkey season. Additionally, many hunters during the first part of the season may be relatively inexperienced. This would contribute to mis- taking hens for gobblers Graphical examination of our data (Fig. 2) revealed a second peak of harvest during week 7. However, this peak was not associated with a similar peak in gobbling activity or hunter num-bers. We believe that this peak may be a reflection of hens leav- ing gobblers to begin incubation. Half of all nest initiations occurred during weeks 7 and 8. We hypothesize that gobblers are more susceptible to calling when they are not with hens, potentially causing them to be more easily harvested without necessarily gobbling more. Additionally, by this late in the sea- son, mostly experienced turkey hunters are in the woods. These hunters may be more proficient turkey hunters thus increasingharvest relative to the number of hunters.Although nest success 2 years previous was correlated with probability of hearing a gobbler, it was not correlated with num-ber of calls heard. This indicated that proportion of 2-year-oldtoms in the population may contributeto the likelihood of hearing an individ-ual turkey gobble. However, within-year factors, possibly on a daily basis,exerted enough influence on gobblingbehavior that it could not be similarlypredicted. Such daily factors may beweather conditions, individual gobblerbehavior and hen presence. Anotherpossible influence is gobbler condition.Gobblers in poor condition may notparticipate in breeding activities.Gobblers lose weight during thebreeding season and rely on their Research conducted by Darren H. Miller,graduate research assistantGeorge A. Hurst. professorand Bruce D. Leopold,professorDepartment of Wildlifeand FisheriesFor moreinformation contact:John E. Gunter, DirectorForest &WildlifeResearch CenterBox 9680Mississippi State. MS 39762601-325-2952 Fax: 601--325-8726 jgunter@cfr.msstate.edubreast sponge for much oftheir energy requirements.Gobblers entering thebreeding season withsmaller energy reservesmay not be able to investas much effort for breed-ing. This may be affectedby winter habitat condi- tions (e.g., available acorns), although it hasnever been investigated. CHRONOLOGY OF EVENTS Figure 2Based on our research, gobbling activity significantlydecreased during the research project and alsodecreased within years as number of days into callcount surveys progressed. The TWMA turkey popu-lation was declining and may have contributed to thedecline in gobbling activity observed across years. Itappears that gobbling activity declined throughout callcount periods, partially due to decreases in the gob-bler population and increases in number of hens incu-bating. However, it is important to note that therelationship to gobbler population size was notstrong enough to predict population levels based ongobbling activity. Decreases in within-year gobble callcounts also may be related to hunting activity.Hunting effort declined with call counts on TWMA.A possible relationship may be that hunters are har-vesting vocal birds, especially those located close toroads. This would lead to observers and huntersbeing less likely to hear gobbling birds, resulting inless hunting effort and lower call counts. Disturbanceof vocal birds also may contribute to declining gob-bling within years.Wind velocity also was negatively related to bothnumber of calls and number of gobblers heard. Thismay have resulted from turkeys gobbling less orobservers being less able to hear gobblers. Hunter numbers significantly increased as gobbling increased. Hunters were more likely to hunt when gobblingactivity was higher and did not hunt when gobblerswere silent.Figure IOur results sug-gested thatsome unmea-sured factors(i.e., gobblercondition, indi-vidual gobbler behavior, presence ofhens) significantly affecteddaily variations in gobblingcall counts so that we wereunable to account for alarge proportion of varia-tion in gobbling activitywithin years. Within central Mississippi, gobbling call counts have limited applica-tion for indexing wild turkey populations. Even accounting for variations in weather, population lev-els, and reproductive parameters, we could not pre-dict gobbling activity. Relationships between numberof calls heard and number of gobblers heard withhunter numbers and hunter success only indicatethat, in years when gobbling activity was high, morehunters were pursuing turkeys with higher successWithin-year gobbling activity was influenced by acomplex interaction of population and environmentalconditions that cannot be easily modeled. This result-ed in a poor ability to predict gobbling activity.Additionally, variables representing population sizewere not strongly related to gobbling activity.Obviously, if there are no turkeys, there will be nogobbling However, just because gobblers are notheard doesn’t mean there are none. Finally an indexof age structure (i.e.. number of 2-year-old gobblersin the population) was demonstrated to positivelyimpact gobbling call counts between years.Hunters need to be aware that a lack of gobblingactivity doesn’t necessarily indicate a lack of gobblers.Conversely, a lot of gobbling may not reflect an abun-dance of gobblers. Researchers and managers wish-ing to implement gobbling call counts to assess popu-lation trends should consider possible alternativemethods, such as harvest information. Our work onTWMA has indicated that number of gobblers har-vested is a good index of gobbler population levels.Gobbling activity appears to be affected by as yetunmeasured factors (e.g., presence of hens, individualgobbler behavior,gobbler condition)in central Mississippi. As such, interpreta-tion of resultsfrom such surveysshould be viewedwith caution.