Monitoring Deer and Deer Damages

A critical element of Green Fire’s mission is managing deer harvests with the goal of limiting the damages deer cause.  The eventual success of our mission, therefore, depends on monitoring deer activity, deer harvests, and the damages deer cause.  Monitoring data will be used to:

• illustrate where deer are over-abundant and damages are highest,
• motivate property owners to participate in deer harvest, monitoring, and educational efforts,
• guide hunting efforts to locations with the greatest deer damages,
• develop the information base for Green Fire’s Directors to assess acceptable levels of damage, and
• give property owners practical purposes and motivation for getting outside and appreciating the plants and wildlife on their properties and neighborhood parks.

The suite of monitoring methods planned for implementation is discussed here.  One of Green Fire’s priorities will be to develop specific instructions for collecting and reporting these types of monitoring data.  GreenFireWeb will provide the instructions for collecting monitoring data and forms for reporting the data from PCs and mobile devices.  Monitoring methods will be designed to be used by property owners, hunters, and others who do not necessarily have technical backgrounds.  An important part of Green Fire’s educational program will be to present training in collection, reporting, and interpretation of monitoring information. 

Deer/vehicle collisions

There are two existing sources of information on deer/vehicle collisions.  Drivers who are involved in an accident that cause injury to any person or that damage another's property are required to report the accident to police.  These represent a fraction of all deer/vehicle collisions, but provide useful data on the resulting economic and health damages.  The other source is reports of deer carcasses along highway rights of way that are reported to the Virginia Department of Transportation.  VDOT hires contractors to collect and dispose of road kills.  The contractors report this data in order to be paid.  More road kills are reported than police reports since many collisions that are fatal to deer do not cause injuries or damage to property other than the driver's vehicle.

Even the VDOT road kill data is not a complete account of deer deaths and injuries from collisions.   Deer that die beyond the highway right of way will not be picked up by VDOT contractors, and deer that are injured but do not die do not get counted, of course.

It is planned that GreenFireWeb will provide a means for anyone to report the location of deer that die by any means including deer that die along highways, by collision but away from highways, or from other causes than vehicle collisions.  As with any Green Fire monitoring data, this information will be reportable by web browser or mobile device.  A mechanism to immediately transmit road kill reports to VDOT will be investigated. 

Lyme Disease, Ticks, and Rodents

The Fairfax County Health Department receives mandatory physicians’ reports of Lyme disease cases.  It also conducts field investigations into the occurrence of deer ticks at locations throughout the County, tests deer ticks for presence of the bacteria that cause Lyme disease, and identifies ticks for County residents.  Green Fire will discuss with the Health Department the possibility of presenting the disease incidence (locations only), deer tick and bacteria incidence information geographically on GreenFireWeb.  Green Fire will also investigate the possibility of leveraging the Health Department’s field investigations by training our contributors to survey for deer ticks, submit samples to the Health Department for Lyme disease testing, and possibly survey for the primary mammalian reservoir of Lyme disease, the white-footed mouse. 

Note on the connection between Lyme disease and deer populations:  The bacterium that causes Lyme disease does not live in deer, so deer are not a reservoir for the bacterium and deer can not transmit Lyme disease to humans.  However, deer ticks require a blood meal three times during their life cycle:  larvae before metamorphosing to nymphs, nymphs before metamorphosing to adults, and female adults before laying eggs.  Deer ticks’ primary source of blood meals, especially the female adults, is deer.  Some studies indicate that reducing deer populations from very dense to moderately dense leaves plenty of deer for tick feeding needs.  It may be that reducing deer densities will have no impact on numbers of deer ticks and, therefore, on number of human cases of Lyme disease, until very low densities of deer are achieved.  More data on this connection are needed.

Deer Harvest

Valuable information about deer can be acquired by hunters.  In addition to numbers of deer taken, the following data will be requested from all hunters harvesting deer in Fairfax County:

• Hunt location, date, start time and end time (on stand)
• Numbers and sex of deer seen during a hunt
• Number of shots taken
• Number of hits
• Weight of harvested deer (by scale or estimated by chest measurement)
• Notes on shot placement, deer behavior, deer disease and injuries, people encountered, conflicts, problems tracking and retrieving, etc.      

Forms for reporting these data will be provided on GreenFireWeb.com.  Hunters will be able to report their data by web browser or mobile device.  Hunt logs will not be made public and will be available only to an archer and his/her organization.  Summary statistics will be displayed on GreenFireWeb.com.

Deer Activity

In areas that have been hunted for some time, hunters will come to know the patterns of deer activity on a property and within a neighborhood.  In anticipation of beginning to hunt a property, during long intervals between hunts, and on properties where hunting will not take place for whatever reason, supplemental information on deer activity would be valuable. 

Besides sitting in a tree stand and watching for hours, the most useful information about deer activity can be obtained by trail cameras.  Property owners can acquire suitable cameras for $100 and up.  Placed near trails, refuges, or food sources, these cameras can record deer that pass within 50 feet or so.  From the photos (or video if so equipped) the number and types (fawn, yearling, adult doe, adult buck) of deer captured during a 24-hour period or longer can be counted and reported.  This information will be useful to hunters of the property and for characterizing deer behavior and abundance over larger areas.

Green Fire with the advice of our partners will develop minimum specifications for trail cameras and define standard reporting protocols for entering deer activity data on GreenFireWeb.com.

Browse Index

In winter deer subsist by browsing shrub, vine, and tree twigs and buds.  The amount of damage caused is important for its own sake because over-browsing can kill the vegetation and can alter the structure and composition of forests.  The amount of damage is also an indicator of deer numbers.  The best time to conduct browse surveys is late winter prior to leaf emergence.  Counting the number of browsed twigs at a measured site is simple, but a large number of sites must be surveyed because deer browsing patterns are very patchy. 

Green Fire with the advice of our partners will select a procedure from among several reported in the literature for choosing sites and counting and reporting browse.  An elaboration of the procedure that adds information on the affected shrub and tree species will be considered.

Seedling/Sapling Count

Under continuous browse pressure, seedling that survive to grow and bear seeds are species that deer avoid such as pawpaw, black cherry, ash, and hackberry.  Oaks, hickories, and maples have less chance of surviving heavy deer browsing. Determining survival of tree seedlings and saplings is another method for monitoring changes in structure and composition of forests.  Seedling/sapling counts are best done after leaves have fully emerged to aid species identification.

As with browse measurements, there are several methods for monitoring seedling and sapling survival. Green Fire with the advice of our partners will select a procedure from among several reported in the literature. 

Indicator Plants – Native

Deer have preferences for some shrubs, vines, trees, and wildflowers over others.  Persistence of favored woodland plants such as orchids and lilies would indicate that deer have more than enough food available to them and are not over-abundant.  On the other hand, when plants that deer browse only in desperation such as jack-in-the-pulpit are not present in settings where they would naturally occur, over-abundance is suspected.  Similarly, when the only plants growing on the forest floor are ones that deer absolutely avoid, such as hay-scented fern and pawpaw seedlings, over-abundance is suspected. 

Green Fire with the advice of our partners will select native plants in each of nine categories:

Deer Preference	Shrub/subshrub	Herb/forb	Fern/fern ally
High
Medium
Low

More than one set of indicator plants may be described in order to encompass various ecological communities reflecting major differences in geology, soils, drainage, or history of use.

Fact sheets for each indicator plant will be developed and posted on GreenFireWeb.com.  Fact sheets may include pictures and/or drawing, identification features, phenology (sprouting, flowering, seed distribution dates), habitat preferences (shade tolerance, soil moisture, pH, calcium availability, slope, etc.), sources for acquiring seed or stock, and uses by wildlife.

As with other monitoring methods, standard procedures for reporting observations of indicator plants will be developed and appropriate input forms will be programmed on GreenFireWeb.com.

Indicator Plants – Horticultural

Three horticultural indicators of deer over-abundance are

• residents decide not to plant gardens knowing that deer will ruin them,
• landscape plants are selected primarily for deer resistance, and
• deer deterrents such as fencing, liquid soap, animal urine, and rotten egg products don’t work (deterrents work better when deer are not desperate for food).

GreenFireWeb.com will provide forms that residents can use to share reports of damages by deer to garden and ornamental plants. 

Ticks 

All residents who are active in their woods or who own pets that go outside should determine whether deer ticks and/or dog ticks are present.

Ticks can be sampled simply by dragging a square of flannel or corduroy over low vegetation and leaf litter along trails used by people, pets or wildlife. The best time to sample is between mid-May and the end of June under conditions that favor tick presence and activity, e.g., when vegetation is not wet and when ambient temperature is above 50 degrees F.  Slowly drag or flag the tick collector along the trail touching the tips of vegetation and contacting leaf litter – hungry ticks will grab on with all their might. Dragging or flagging success depends upon the degree of contact between the cloth and ground or vegetation surface.   Pick all ticks off with tweezers and transfer to a wide-mouthed jar containing rubbing alcohol (70% ethanol).

To learn how to distinguish between the nymph and adult stages of ticks or between the deer ticks that carry Lyme disease and the dog ticks that carry Rocky Mountain Spotted Fever, download Virginia State Health Department's "Preventing Tick-Borne Diseases in Virginia".

Rodents

Rodents, especially the white-footed mouse, are the primary hosts of the Lyme disease bacteria.  Much more needs to be learned about the complex interactions among deer, ticks, and rodents to understand the likelihood that deer control will reduce the incidence of Lyme disease in humans.  Methods for monitoring rodents remain to be described.  Monitoring will likely based on setting Sherman live traps in transects.  Scheduling, spacing, safety precautions, identifying animals captured, and other survey factors need to be developed.