# Qualitative Identification of Forage Remnants in Deer Feces

> Can you tell what a deer ate from their droppings? In this 1969 study, captive mule deer and a white-tailed deer were fed one plant at a time, and every one of 17 plants left recognisable fragments in the pellets under the microscope. But even on a single-plant diet, only a small share of what went in could be identified, a warning for anyone hoping to measure wild deer diets from scat alone.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/1969-zyznar-urness-qualitative-identification-forage-remnants/

## Citation and access

- **Authors:** Edward Zyznar and Philip J. Urness
- **Year published:** 1969
- **Journal or source:** The Journal of Wildlife Management
- **Full citation:** Zyznar, E. and Urness, P. J. 1969. Qualitative identification of forage remnants in deer feces. The Journal of Wildlife Management 33(3): 506–510.
- **DOI:** 10.2307/3799372
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.2307/3799372

## Tags

- **Species:** Mammals > Mule deer; Mammals > White-tailed deer
- **Region:** North America > United States
- **Tracking:** Scat; Tracking
- **Behaviour and ecology:** Behaviour; Feeding
- **Data type:** New field data
- **Observer qualification:** Not needed
- **Discipline:** Behaviour and ecology
- **Year published:** 1969

## Detailed keywords

- **Species:** Studied: captive mule deer (Odocoileus hemionus), two animals, and white-tailed deer (Odocoileus virginianus), one animal. Forage plants fed to the mule deer: crested wheatgrass (Agropyron cristatum), mountain muhly (Muhlenbergia montana), alfalfa (Medicago sativa), horse cinquefoil (Potentilla hippiana), dandelion (Taraxacum spp.), cliffrose (Cowania mexicana), true mountain-mahogany (Cercocarpus montanus), Gambel oak (Quercus gambelii) and quaking aspen (Populus tremuloides). Browse plants fed to the white-tailed deer: desert ceanothus (Ceanothus greggii), hollyleaf buckthorn (Rhamnus crocea), jojoba (Simmondsia chinensis), birchleaf mountain-mahogany (Cercocarpus betuloides), shrub live oak (Quercus turbinella), Wright silktassel (Garrya wrightii), yellowleaf silktassel (Garrya flavescens) and mistletoe (Phoradendron villosum). Animals mentioned from earlier fecal and stomach studies: squirrels, cottontail rabbit (Sylvilagus floridanus), red fox (Vulpes sp.), snowshoe hare (Lepus americanus), quokka (Setonix brachyurus), red deer (Cervus elaphus), roe deer (Capreolus capreolus), chamois (Rupicapra rupicapra) and waterbuck (Kobus sp.).
- **Location and habitat:** Arizona, United States: mule deer penned at Flagstaff, the white-tailed deer at the Phoenix Zoo; the research was carried out at Tempe with Arizona State University. Captive animals in small pens.
- **Topics:** fecal (scat) analysis of diet; identifying plant fragments in deer pellets under the microscope; plant epidermis, leaf veins, plant hairs (trichomes), stomata and gland cells as identification characters; grasses versus broad-leaved plants; reference collections (epidermal mounts, photomicrographs, preserved fecal remnants); marker dye (basic fuchsin) and salt to mark the droppings from a test meal; time from feeding to droppings (about 36 hours); deer refusing some forage plants when offered alone; limits of quantitative diet analysis from feces.
- **Statistics or models:** None
- **Data type:** New field data from a captive feeding trial (dates not given; the paper was received for publication on 4 November 1968), with a review of earlier fecal and stomach analysis studies. Small inconsistency: the running page headers read “Quantifying forage remnants in deer feces”, while the title is “Qualitative identification”; the study itself is qualitative. The abstract says unstained epidermal mounts made from fresh plants, with photomicrographs, were superior, while the recommendations prefer preserved, positively identified fecal remnants over prepared mounts as reference standards.

## Synopsis

### 1. What they did

Studying what deer eat by looking at their droppings would allow unlimited sampling, but deer chew and digest plants so finely that the pieces left in their pellets can only be identified under a microscope. The authors set out to find which plant structures can be recognised in deer droppings, and to develop a practical way to identify them.

- Feeding trials. Two mule deer (at Flagstaff) and one white-tailed deer (at the Phoenix Zoo) were kept in small pens on a standard diet of rolled barley, commercial pellets and alfalfa. The researchers first checked the droppings from this diet, so they could tell its remains apart from the test plants. Then each deer was offered one forage plant at a time, alone and in plenty, treated with a red marker dye and salt. Only dyed droppings were collected. In all, 17 tree, shrub and herbaceous plants were tested.

- Preparing the droppings. About 20 pellets per sample were soaked overnight or boiled for 15 minutes in sodium hydroxide to remove the mucus coat, stirred to a pulp, rinsed and examined wet under a microscope at 7 times magnification, then at higher power up to 100 times when nothing could be recognised.

- Reference material. Fragments were identified by comparing them with the outer skin (epidermis) peeled from fresh leaves and stems with acid, and with photographs taken through the microscope (photomicrographs). Confirmed fragments were kept in formalin to help identify the diets of wild deer.

### 2. What they found

- Recognisable fragments were found for all 17 plants, but the magnification needed (7 to 100 times) depended on the plant. Using more than 7 times magnification increased the share of material that could be identified.

- Useful identification features were: (1) the pattern of leaf veins; (2) plant hairs (trichomes), whether present, how dense and their shape; (3) the shape of the epidermal cells; and (4) larger pieces such as leaf fragments, buds, flower parts, seeds and woody tissue.

- Grasses were easy to tell from broad-leaved plants by their parallel veins, rectangular cells and breathing pores (stomata) with two guard cells and two accessory cells.

- Some plants, such as Wright silktassel (with distinctive gland cells) and jojoba (with distinctive breathing pore pattern, thick-walled cells and partitioned plant hairs that survived digestion intact), were easy to recognise. Others needed careful comparison with the fresh-plant reference mounts.

- Permanent stained reference slides, as used for stomach contents, did not work well for droppings: each plant needed many slides to show all the structures that survive digestion, and the stains took too much time.

- Deer often refused some plants when offered alone, even though wild deer commonly eat them. Some deer would only eat them after up to 3 days without food; putting salt on the moistened plants helped a little.

- From the marker dye, food took about 36 hours to pass through. The most remnants usually appeared after that, because the deer did not eat much of a new plant straight away, and coarse browse seemed to pass more slowly than concentrates and herbaceous plants.

- Even on a single-plant diet, droppings seldom contained more than a low percentage of recognisable fragments.

### 3. What they concluded

- To identify more fragments, the authors recommend: (1) not limiting the microscope work to low power (7 times); (2) using preserved, positively identified fragments from droppings as reference standards rather than prepared mounts; and (3) building a file of good photomicrographs, with colour slides especially helpful for unstained material.

- Because so little of what a deer eats stays recognisable, reliable quantitative diet analysis from deer droppings will be seriously limited, especially for wild deer, which tend to eat small amounts of many plants.

### 6. Other technologies, skills or innovations

- A marker dye (basic fuchsin) and salt added to a single test plant, so that only droppings from that meal were collected.

- Acid-peeled epidermis of fresh plants, stored in glycerin, and photomicrographs as a reference library.

- Preserving confirmed fragments from droppings in formalin as reference standards.

## Cite this summary

Lawrence, K. 2026. Summary of: Qualitative Identification of Forage Remnants in Deer Feces (Zyznar and Urness, 1969). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/1969-zyznar-urness-qualitative-identification-forage-remnants/