Deer Damage Abatement Research Project

PROEJCT BACKGROUND
My farm is a 140 acre certified tree farm located west of Bellevue in Jackson County. The farm has an approved forest management plan and includes a five acre clear cut replanted, direct seeding replanting, and timber stand improvement on much of the existing timber. The farm also contains 96 acres of cropland.

The Southfork of Big Mill Creek, a cold water stream in Jackson County, flows through the farm and was included as part of a water quality protection project. Part of the overall management plan for the farm includes excluding livestock from the forestland and from the riparian corridor of this cold water stream.

As an Iowa tree farmer, I have experienced significant damage to newly planted trees from deer browsing and by buck rubs. This is significant detriment to landowners that are interested in planting trees on marginal land.

I am a past President of the Iowa Woodland Owners Association. Deer damage and methods of control is an extremely important and controversial issue to many of their members. If a simple, low cost effective method can be documented to reduce deer damage it will have significant benefits to the woodland owners in eastern Iowa and surrounding areas. This method may also benefit specialty crop producers such as nursery stock, Christmas trees, and nut tree farmers who are trying to protect higher value crops from deer damage.

PROJECT DESCRIPTION AND RESULTS
The project was to conduct an evaluation of the effectiveness of sisal twine in reducing deer damage using more controlled methods in order to generate data documenting the results to share with other tree farmers in eastern Iowa.

Methods:
In an area with existing young trees which had experienced heavy browsing damage, sisal baling twice was evaluated as a means to protect the terminal leader on the young trees from deer damage.

Prior to September 1, 1998, 101 trees in a 400 yard stretch along a field woods border were selected. The species composition was red oak, walnut, white oak and bur oak. 64 of the trees were walnut. All chosen trees were about 3 feet high (range of about 2-4 feet). A 6 inch strand of sisal twine was tied around the leader of alternate trees (total 51). In most cases, the sisal covered the terminal bud. All trees were identified with a numbered piece of wood lath placed at the base.

Results:
Most of the snow cover was gone by February 15th when the trees were checked. The following table shows the results.

Table 1
Sisal: leader damage*: 4/52 = 7.8%, lateral limb damage: 40/51 = 78%
Control: Leader damage: 20/50 = 40%, Lateral limb damage: 36/50 = 72%

A total of 76 of the 101 trees or 75.2% had been visited by deer.
*Leader damage details: 2 –sisal had slipped down, bud was chewed off.
1 – Sisal in place with bud chewed off
1 – Buck broke off upper plant and bud damaged

There was more snow the end of February and early March. The trees were rechecked on March 17 with the following results.

Table 2
Sisal: leader damage*: 4/51 = 7.8%, lateral limb damage: 44/51 = 86.2% (+4)
Control: leader damage*: 26/50 = 52.0% (+6), lateral limb damage: 42/50 = 85.0% (+6)

Overall, deer visited 86 of the 101 trees or 85.1%. No additional deer damage assessments were conducted in accordance with project procedures.

However, in late July several sisal wrapped project trees were spot checked to observe the effect of the wrap on tree growth. Some wrapped trees had produced terminal growth exceeding 30 inches. Approximately 40 inches of terminal leader growth was observed on one Red Oak with signs of slight girdling produced by the sisal wrap. I also observed deer browse damage on wrapped trees previously undamaged, so there was a down side to the observations. Not all trees were checked as this observation was beyond the scope of the project.

Part II
The project was implemented in conjunction with a new tree planting on a 7.8 acre riparian buffer area on the farm. In this area two methods of deer damage control were evaluated on newly planted trees. Riparian buffer field plots of newly planted trees were established with one plot surrounded by three strands of sisal baling fence, one plot surrounded by one strand of electric fence, and one plot of 100 trees not protected by any fence. The plots were established in an area where all plots would be likely to experience similar deer pressure. Each plot was approximately 50’x90’ and contained about 100 trees (83-108).

The trees were to have been planted in the fall of 1998; however, weather delayed “hardening off” at the State Nursery. Given a late planting date of mid to late November, the tree order was rescheduled until April, 1999. The project trees were included in these planting utilizing approximate 600 trees per acre. Red oak, white oak, walnut, white ash and willow were planted. White pines were added as specific by the Iowa DNR to enhance appeal to browsing deer. All trees were planted in holes dug and packed by hand. By June, tree viability appeared to be good, and weed control had been initiated.

On June 17, Jim Janson, Iowa DNR Wildlife Depredation Biologist, constructed the electric fences, and the sisal fencing was installed and the control plots delineated.

Results:
The first tree assessment was conducted on June 19, 1999. All trees in each plot were checked weekly there after until May 17, 2000 and deer damage by browsing was noted. By early August 1999, a number of trees in each plot had died of causes not thought to be related to deer damage (early morality). Sporadic deer browsing was noted in each plot through the summer and fall and seemed to increase in early December. Hunting seasons seem to increase deer movement, and the onset of cold weather usually increases the number of deer staying in the area for shelter, food and water. Snowfall in early December made it impossible to access individual tree damage. Therefore, no assessments were made until the final assessment on May 17, 2000. Weekly checks were continued throughout the winter and spring to insure fences were intact. The final evaluation came after all trees had budded out. The inspection revealed whether each tree was dead or alive and whether damaged or undamaged. Unfortunately, a few trees (mainly red oak) had been chewed off at ground level, probably by rabbits. Some had re-spouted while a few others had not indicated any re-growth.

The results of the final inspection are summarized in table 3.

Table 3
Area, plot type, total trees planted, alive after 1 month, undamaged 5/17/00, dead/damaged 5/17/00, percent damaged
1, electric, 108, 99, 11, 88, 88.9
2, control, 86, 77, 4, 73, 94.8
3, sisal, 88, 80, 5, 75, 93.8
4, control, 83, 76, 6, 70, 92.1
5, electric, 96, 85, 22, 63, 74.1
6, sisal, 107, 95, 25, 70, 73.7

Discussion:
The project clearly did not provide the insight and benefits investigators had believed were possible. While the cost of wrapping the terminal leader with sisal is minimal, the effort may be a deterrent. Individual tree treatment takes less than a minute, however results in terms of leader protection are nearly certain. If though leader protection the tree is able to quickly grow beyond the height where deer browse damage occurs, the effort may be rewarded.

OUTREACH
The methods and results of this project have been presented to several groups. The project was included in the program for the Annual Limestone Bluffs RC&D Board Meeting in August of 1999. Slides were shown and results were presented.

Jim Janson with the Iowa DNR presented information about the Deer Damage Abatement Project at the 1999 Annual Iowa Woodland Owners Association Meeting which 70 woodland owners attended. The project and final report will be presented at the 2000 Iowa Woodland Owners Annual meeting to be held in August.

A Forestry Field Day is being planned for 2001 in cooperation with Iowa State University Forestry Extension. The Forestry Field Day generally draw about 100 people and this will be a good opportunity to show the future results of the project.