Missouri is loaded with turkeys, and that doesn’t even include the human kind. Turkey hunting is a substantial recreational activity in Missouri, and hunters spend more than 500,000 days afield each year (Missouri Department of Conservation 2013). Consequently, the Missouri Department of Conservation monitors turkey population trends. No way of doing it is perfect, so they do it several different ways.
Turkeys are not really a “canary-in-the-coal-mine” species, and their population levels can change due to how much hunting pressure they experience, as well as for reasons that would be of more interest to this blog, such as habitat destruction and environmental pollutants. Nevertheless, they are a major large species, and provide one bit of information about how well Missouri’s land can support life.
One major way the Department monitors turkey population is to track the number of turkeys killed by hunters each year. The spring season is the largest, and during it Missouri hunters kill lots of turkeys! In 2015 hunters bagged 48,432 wild turkeys during the spring season. In 2013, they bagged 47,601. The harvest hit its highpoint in 2004 at 60,744, then declined by almost 1/3. Since 2011 it has been increasing again. The first chart at right shows the trend. You can see that the number of kills increases rather dramatically from 1960 through 2004, then declines, then increases again (yellow line). Notice that the number of hunting permits (green line) follows a similar trajectory. One might be tempted to attribute the fewer kills to less hunting. Data below does not support that interpretation, however.
(Click on chart for larger view.)
Another way the Department monitors turkey population is through a survey conducted with the voluntary cooperation of bowhunters. Participants report sightings of turkeys to the Department. Because how many turkeys you see may depend on how many hours you spend in the field, the Department constructs an index by dividing the number of sightings by the number of hours in the field. For our purposes, the raw index doesn’t really mean much, so the chart at right shows change in the index for regions in the state over several time periods. The 1-year trend was toward more sightings, but over every other time period the trend was toward fewer sightings, in some places a lot fewer. (See the report for a map of the various regions.)
A third way the Department monitors turkey population is to send its staff into the field to look for turkeys. During this survey, the Department is especially looking to see how many female turkeys have young with them, called poults. The poult-to-hen ratio is considered a marker of whether conditions are favorable for turkey breeding and survival. The third chart at right shows the trend in the poult-to-hen ratio in Missouri from 1950 to 2014. The ratio peaked in during a 20-year period from 1970-1989, and it has declined since then.
Combined, these three reports suggest that there are a lot of turkeys in Missouri. The trends seem to suggest that conservation practices during the 1970s and 1980s led to an increase in breeding success, which then led to an increase in the number of turkeys in Missouri, and the number of turkeys seen and killed by hunters. The bowhunter survey, which only goes back to 1989, suggests that over the last 20 years turkeys have gotten harder to spot. Whether that means they are more wary or that their numbers are declining is not obvious from this data. The decline in the poults-to-hens ratio could have occurred because of environmental problems, or it could simply be a sign that the turkey population reached its saturation point.
The Department is in the midst of a 5-year study to investigate the health and the needs of Missouri’s turkey population.
Missouri Department of Conservation. 2013. 2013 Missouri Wild Turkey Harvest and Population Status Report. Viewed online 10/31/15 at http://mdc.mo.gov/sites/default/files/resources/2014/07/2013wildturkeyreport.pdf.
Missouri Department of Conservation. 2014. 2014 Missouri Wild Turkey Harvest and Population Status Report. Retried online 10/31/15 at http://huntfish.mdc.mo.gov/sites/default/files/downloads/2014TurkeyStatusReport_0.pdf.