White-tailed deer food habits in northeastern Mexico

Small Ruminant Research ELSEVIER

Small Ruminant Research 25 (1997) 141-146

White-tailed deer food habits in northeastern Mexico R.G. Ramirez ‘3* , J.B. Quintanilla b, J. Aranda b a Facultad de Medicina Vererinuria y Zootecnia, Uniuersidad Aut6noma de Nueoo Lecin, San Nicolcis de 10sGarza, N.L. Mexico b Facultad de Agronomia, Universidad Auto’mwnade Nuevo Le6n, San Nicokis de 10sGorza, N.L. Mexico

Accepted 26 August 1996

Abstract Microhistological analysis of feces was used to estimate the selection of white-tailed deer (Odocoileus uirginianus, Tex.) in the state of Nuevo Leon in northeastern Mexico. Browse was the main component of deer diets (94% annual mean). Major species were blackbrush acacia (Acacia rigid& Benth), guajillo (Acacia berlandieri Benth) soapbrush (Porlieria angustifolia Englem), cenizo (Leucophylium texanus Benth), huisache (Acacia farnesiana L), popotillo (Ephedra aspera Englem), palo Verde (Cercidium macrum I.M. Johnst) and honey mesquite (Prosopis glandulosa Torr). These species represented about 82% the total plant composition of deer diets on an annual basis. Forbs were numerous (23 species in deer diets), but represented only about 5% of the total annual diet. Major forbs in deer diets were Hibiscus spp., Zephyranthes arenicofu Hansel, Agrythamnia neomexicana Muell and Dyssodiu acerosa DC. Grasses were selected by deer in very low amounts; buffelgrass (Cenchrus ciliaris L.) was the major grass in the annual diets of deer. Because of the nature of deer diets, it is concluded that browse should be considered an important part of the deer habitat, and that those shrub species that are used by deer for food and refuge should be preserved. 0 1997 Elsevier Science B.V. Keywords; White-tailed

deer; Botanical

composition

of diets; Northeastcm

1. Introduction White-tailed deer is the most important game animal in northeastern Mexico. In recent years ranch owners have used this wildlife resource for profit.

There have been very few scientific studies on white-tailed deer in northeastern Mexico and their food habits are still unknown. Ranchers want to adopt range evaluations to keep big game popula-

* Corresponding address: Fat. de Med. Vet. y Zoot., UANL, Apartado Postal 142, Sucursal F, San Nicolls de 10s Garza, N.L. CP. 66451, Mtxico. Tel: (8) 357-6015; fax: (8) 365-0968; e-mail: [email protected].

Mexico

tions and their habitat in balance. Knowledge of the food habits of deer would allow realistic habitat evaluation based on forage supplies (Gill et al., 1983; Gallina, 1993). However, accurate estimates of diets of foraging wild animals are not easy to obtain. Fecal analysis has been recommended for evaluating wild herbivore diets in many situations (Holechek et al., 1982). Fecal analysis generally results in higher estimates of grasses, trees and shrubs, and lower estimates of forbs in herbivore diets (Warren et al., 1984; Ramirez, 1989). However, dietary trends and relative

importance

value rankings

of individual

plant

species in diets as determined

by fecal analysis

accurate

This

(Vavra

et al.,

1978).

ducted with the objective

00921-4488/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. PII SO921 -4488(96)009601

study

of characterizing

are

was con-

the an-

R.G.

142

Ramirez

et ~1. / Smd

Ruminant

nual diets of white-tailed deer grazing on rangelands in northern Nuevo Leon, Mexico.

2. Materials

and methods

2.1. Study area The study was conducted during 1988 and 1989 on four ranches, two in Anahuac, one in Par&, and the other in Vallecillo counties of Nuevo Leon, in northeastern Mexico. The total area was about 12 000 ha. The climate is semi-arid, with an average annual precipitation of 500 mm, and temperature of 21°C (Garcia, 1964). However, precipitation during the year of the study was only 384 mm, which occurred mainly during July through September. The plant community is similar to the Eastern Coastal Plain shrub described by Muller (1939) and is found in the area where the high plateau gradually descends to the Northeastern Coastal Plain. The topography of the region can be described as flat, and most of the soils are sandy loam and sandy clay loam. The vegetation is characterized by a mixed-brush complex consisting primarily of honey mesquite (Problackbrush acacia (Acacia sopis glandulosa), rigid&a), cenizo (Lucophyllum texanum) and huisache ( Acacia farnesiana). Major grasses included red grama (Bouteloua trifida), threeawns ( Aristida spp.> and buffelgrass (Cenchrus ciliaris). Associated forbs were Suaeda sp., Ruda sp., Wedelia sp., and Palafoxia texana, among others. Estimated stocking rate for this community was 18 ha per animal unit (COTECOCA, 1968).

2.2. Botanical analysis of the study areas and feces The line intercept method (Canfield, 1941) was used to estimate cover and botanical composition of study area. Sixty transects 10 m long were distributed randomly in the study areas (15 on each ranch). Measurements of vegetation were taken in May 1989. Canopy cover of shrubs and basal cover of herbaceous species were measured. By the time collections were made, only three ranches (10 000 ha) were moderately grazed by cattle. About 700 head of cows and calves were freely grazing. A composite fecal sample of 15 fresh single

Reseurch

25 (1996)

141-146

defecations was collected monthly on each ranch from June 1988 through May 1989. Five microscopic slides were prepared from each composite sample. Botanical composition (dry weight) of white-tailed deer diets was determined by examination of epiderma1 tissues of plant species in feces at 125 X magnification in 20 fields on each slide (Sparks and Malechek, 1968). In the study area identified plants were collected and used for reference tissue to identify plants in feces by epidermal cellular characteristics. 2.3. Statistical analysis Deer diet data were reported by individual species and by groups of plants on each ranch, and were subjected to analysis of variance using a randomized block design (Statistical Analysis Systems Institute Inc., 1988) to determine monthly differences. Means were separated using the least significance difference method (LSD); when significant (P < 0.05) F tests were reported (Steel and Torrie, 1980).

3. Results and discussion 3.1. Composition of the study area Plant cover of the grazed areas (Table 1) was about 68% for trees and shurbs, 19% for grasses and 13% for forbs. The most important plant species were honey mesquite and blackbrush acacia. Both represented about 34% of total availability of plant species in the study areas. The forb Suaeda sp., represented about 12.5% of the cover composition. The most abundant grasses were Bothriochloa annulatum and Buchloe dactiloides with about 10% of total composition. 3.2. Composition of diets Fifty-nine plant species were identified in whitetailed deer diets (Table 2). Browse was the main component in deer diets (94% annual mean>. Total browse consumption did not differ (P < 0.01) among sampling periods. During spring months, however, deer consumed large amounts of shrubs. The lower consumption of shrubs was found during March and

R.G. Rumirez et al./Smull

Ruminant Research

Table 1 Botanical composition (o/o) during May 1989 of the four ranches in northeastern Mexico where white-tailed deer food habits were determined Species

(%I

Shrubs a Acaciu rigidula Benth. Prosopis glandulosa

Torr. Porlieria ungustifolia Engelm. Opuntia leptocaulis DC. Condalia lycioides Hook. Acuciu farnesiana L. Acacia herlundieri Benth. Aloysia gratissima Gill and Hook. Opuntia lindehimieri Engelm Kurwinskiu humholdtiana R. and S. Leucophyllum texanum Berl. Jatropha

dioica Cerv.

Eysenhardtia

texana Scheele.

Condalia obovata Hook. Celtis pallida Torr. Lycium berlandieri

Dun. Torr. Castella texana T. and G. Rose. Ziziphus obtusifolia T. and G. Parkinsonia aculeutu T. and G. Diospyros texanu Scheele. Ephedru aspera Engelm. Larrea tridentala DC. Subtotal Lantano macropada

17.3 16.9 2.2 2.1 2.3 5.3 2.3 2.6 3.3 1.5 1.6 1.8 0.7 0.6 0.7 0.5 2.3 1.0 0.4 0.4 0.4 0.2 0.2 67.0

Forbs a Suaeda sp Senecio confusus

Brittn. Coldenia greggii T. and G. Erionerum avenaceum L. Ruellia corzoi Tram and Burkl. Cynanchum barbigerum Scheele. Wedelia sp. Euphorbia postrata Ait. Palafoxia texana DC. Bernardino sp. Ruda sp. Subtotal

10.4 0.7 0.5 0.3 0.3 0.2 0.2 0.1 0.1 0.1 0.1 13.0

Grasses a Puppophorum

bicolor

Foum.

Chloris cuculata Swarts. Aristidu longicetu Cenchrus

L.

ciliaris L.

Panicum hallii Vasey. Aristida

sp.

Setaria macrostachya Bouteloua

H.B.K.

trifida Thrub.

Buteloua grucilis

H.B.K.

0.3 0.3 0.3 1.1 1.1 1.6 0.6 2.6 0.3

25 (1996) 141-146

143

Table 1 (continued) Species Eragrostis

(%o) mexicunu

Homem. Botriochloa annulatum Kuntze. Buchloe dactilides Nutt. Sporobolus pyamidatus Lam. Subtotal

0.3 4.6 4.3 1.6 19.0

a The following species were found in traces: Shrubs (Foriestera sp.,’ Acacia tortuosa L. and Cercidium macrum I.M. Johnst); Forbs (Heliotropium angiospermurn Murr, Dyssodiu acerosa DC., Aphanostephus sp., Solanum eleangnifolium Cav., Hibiscus cardiophylus Gray, Ruelliu pedunculatu Torr., Parthenium sp., Oxalis dichundroefoliu Gray, Agryfhumniu neomexicana Muell Arg., Zephyranthes arenicolu Hemsl, Physalis sp., Side filicaulis T. and G., Grymnosperma glutinosum (Spreng) Lees, and Paulothamus sp.); and Grasses (Trichloris sp., Chloris ciliata Swartz, Sporobolus aeroides L., Chloris cucullata Bisch, Eragrostis sp., Boutelova curtipendula Torr, Heteropogon conturius (L.) Beaur., Digituria californica (Scribn and Merr) Femald, and Hilaria belungieri Steud).

October. Main shrubs in deer diets was blackbrush acacia, soapbrush (Porlieria angusrifolia), guajillo ( Acaciu berlundieri), cenizo and huisache, among others. These shrubs usually have green foliage during the entire year, as a result of mild winter temperatures; however, blackbrush acacia retains more green foliage during most winters (Warren et al., 1984; Ramfrez et al., 1993). Blackbrush acacia was the major shrub consumed by deer throughout the year (about 51% annual mean). During September and October, deer consumed less (P < 0.01) blackbrush acacia compared with other months (Table 2). It seems that because of its wide distribution in these regions, blackbrush acacia represents an important plant species in small ruminant diets. Studies conducted in the area (Ramirez et al., 1993) have reported that Spanish range goats avidly consumed blackbrush acacia, i.e. it constituted about 56% of the annual diet. Microhistological analysis of feces may overestimate the amount of browse consumed by deer. Ramirez (1989) compared botanical composition of feces and extrusa samples from grazing Spanish goats in northeastern Mexico, and concluded that fecal analysis overestimated browse by about 12%. Gill et al. (1983) and Warren et al. (1984) also reported overestimation of shrubs by microhistologi-

R.G. Ramirez et al./Small

144

Ruminant Research

cal fecal analysis of mule deer and Spanish goats, respectively. However, the fecal analysis technique when used with caution seems appropriate for estimating diet composition of wild ruminants (Holechek et al., 1982; Gill et al., 1983). Forbs were also numerous in deer diets, with 23 species observed throughout the year (Table 2). However, total forbs did not differ (P > 0.05) be-

Table 2 Plant composition

(%) of white-tailed

Species

deer diets in northeastern

25 (1996)

141-146

tween months. Deer consumed more forbs during rainy months (October 8.3%, November 7.9% and March 7.5%) compared with other months. In June (1 .l%) deer selected the lowest amount of forbs (Table 2). Primary forbs in deer diets were Hibiscus sp. (44% of total forb selected by deer), Zephyranthes arenicola (19%), Agrythamnia neomexicana (17%) and Dy sso d ia acerosa (2%). Forbs repre-

Mexico as determined

1988

by microhistological

analysis of fecal material

1989

Mean

SE a

SIG b

Jun.

Jul.

Aug.

Sep.

Oct.

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

May.

43.0 11.0 1.6 9.9 2.7 0.9 2.9 1.5 I .7 6.2 1.1 1.3 0.5 4.6 3.2 6.2 98.4

43.1 7.8 0.6 8.6 0.9 2.3 6.1 3.2 1.8 10.0 2.2 1.4 0.1 1.2 1.2 4.8 95.2

50.5 14.9 3.0 2.0 4.9 2.3 0.5 6.2 0.1 3.4 1.1 0.2 1.0 2.5 0.2 2.2 94.7

32.7 5.8 1.6 4.8 13.6 8.0 0.5 7.2 0.1 0.1 2.8 0.9 2.7 5.3 0.3 6.9 93.3

37.7 5.9 2.9 2.5 15.3 10.3 1.5 5.2 0.2 0.0 2.2 0.9 2.5 0.5 0.5 4.0 91.6

51.6 2.8 4.1 5.9 10.9 9.0 2.6 1.8 0.0 0.0 0.9 0.8 0.6 0.6 0.5 1.2 92.2

58.8 4.2 6.6 4.6 6.6 4.7 2.4 0.7 0.3 0.0 0.4 0.2 0.5 0.0 0.1 4.6 94.4

64.3 7.2 6.2 4.1 0.5 2.5 0.4 0.0 0.0 0.5 0.0 0.4 0.0 0.8 5.3 95.1

50.8 9.7 11.1 4.2 0.1 3.0 0.8 0.1 0.1 0.0 0.2 0.0 0.6 0.0 0.0 5.8 93.5

47.6 7.0 7.4 14.7 0.1 1.1 1.3 0.1 2.7 0.2 0.7 0.4 0.7 0.2 0.0 5.6 91.2

52.3 8.4 1.6 16.1 0.2 0.4 0.4 0.2 4.0 I .5 1.6 3.1 0.3 0.2 0.2 3.6 95.3

69.5 4.5 0.4 7.0 0.0 1.2 0.4 0.8 0.8 4.5 1.7 2.6 0.5 0.6 0.1 1.3 94.2

50.7 7.4 3.9 7.0 4.6 3.8 1.8 2.3 1.3 2.2 1.3 I.0 0.8 1.2 0.5 4.3 94.1

5.9 3.6 3.6 2.9 1.9 1.6 1.1 1.4 0.8 1.3 0.9 0.8 0.4 1.0 0.4 2.4 3.1

** d NS ’ NS ** ** ** NS ** ** ** NS NS ** ** ** NS NS

Other forbs Total forbs

0.2 0.0 0.0 0.0 0.6 1.1

0.3 2.4 1.o 0.0 0.9 4.6

0.9 0.8 3.1 0.0 0.5 5.3

4.1 0.2 1.8 0.6 0.0 6.7

7.5 0.0 0.0 0.2 0.6 8.3

7.0 0.0 0.6 0.0 0.2 7.8

3.1 0.1 0.5 0.2 0.5 4.4

1.6 0.8 0.2 0.2 0.8 3.6

0.4 2.4 0.1 0.2 2.1 5.2

3.0 3.1 0.5 0.0 0.9 7.4

0.5 0.0 1.9 0.0 2.0 4.4

1.5 0.0 2.9 0.1 0.8 5.4

2.5 0.8 1.1 0.1 0.8 5.3

1.7 0.9 1.0 0.1 0.8 3.1

NS ** NS NS NS NS

Grasses s Cenchrus ciliaris Other grasses Total grasses

0.4 0.1 0.5

0.2 0.0 0.2

0.0 0.0 0.0

0.0 0.0 0.0

0.1 0.0 0.1

0.0 0.0 0.0

0.3 0.9 1.2

0.5 0.8 1.3

0.9 0.4 1.3

0.9 0.5 1.4

0.1 0.2 0.3

0.4 0.1 0.5

0.3 0.3 0.6

0.2 0.4 0.4

** NS NS

Shrubs s Acacia rig&da

(L) e (L)

Acacia berlandieri Leucophullum Porlieria

texanum (L)

angustijolia (L)

Acaciafamesiana

(L) Ephedra aspera (L) Opuntia sp. (L) Cercidium mucrum (L) Opuntia lindenimieri (F) Prosopis ~lundulosa (F) Diospyros texanum (F) Castella texana (F) Prosopis glandulosa (L) Yuca sp. (F) Jatropha Dioica (L) Other shrubs Total shrubs

f

1.9

Forbs s Hibiscus

sp.

Zephyrunthes

arenicola

Agrythamnia

neomexicuna

Dyssodicr acerosa

a SE: Standard error, n = 4; b SIG: Significance; ’ NS: Not significant; d * *(P < 0.01); e L: Leaves; ’ F: Flowers; g The following species were found in trace amounts: Shrubs (Larrea tridentada, Parkinsonia aculeata, Opuntia leptocaulis, Calliandra confirta Gray, Cassia greggii Gray, Desmanthus virgatus L., Lycium berlandieri, Castela texana (T. and G.) Rose, Celtis pallida, Cordalia obovata. Acacia greggii Gray, Atriplex spp., Yuca sp., Bumelia lanuginosa Michx, Aloysia gratissima Gill and Hook and Krameria ramosissima Gray); Forbs (Heliotropium angiospermurn Murr., Zexmenia hispida H.B.K., Rhus sp.. Abutilon parvalum Gray, Solanum eleagnifi,lium, Pdaji~xia texana, Lantana macropada Torr., Hibiscus cardiophyllus, Polianthes maculosa Hook., Cynanchum barbigerum Scheele., Arthemisia mexicana L., Coldenia greggii. Veroena sp., Sida Filicaulis, Ruellia corzoi, Dysodia micropoides DC., Aphanostephus sp., Dalea pagonathera Gray and Oxalis dichandroejdia) and Grasses (Boatrichloa anndatum, Seturia macrostachya, Aristida sp. and Panicum

hallii).

R.G. Ramirez et al. /Small

Ruminant Research

sented the second most important group of plants in deer diets. However, Everitt and Drawe (1974) found in south Texas, USA that forbs were the most preferred food item by rumen content analysis of white-tailed deer. Forbs comprised about 37% by volume of the diets, browse 33% and cacti 18%, while grass comprised only 2%. Forbs were consumed by deer seasonally when availability was high. Studies conducted by Drawe (1974) found that deer in Texas, USA, had highest forb consumption during March, April, and May, whereas the lowest forb use was during September through February. Conversely, in this study, deer selected more forbs during September, October, November and March. Forbs may have been underestimated because of the browse overestimation problem mentioned previously and because of high digestibility of forbs (Sanders et al., 1980). Cultivated and native grasses produce higher amounts of available forage compared with shrubs. However, deer in this study consumed lower amounts of grasses throughout the year (0.6% annual mean). During winter (December, 1.2%; January, 1.3%; February, 1.3%; March 1.4%) deer selected higher amounts of grasses compared with other seasons. In general, in winter months deer consumed less forbs and shrubs. Yantis et al. (1983) reported that grasses are not selected by deer when there is sufficient availability of palatable shrubs and forbs. Other studies have concluded that white-tailed deer ate grasses when their habitat is modified (but the amount of grasses in the total deer diet was not more than 1% (Drawe, 1974)), or when forage availability and quality was modified (Gallina, 1993). Pollock et al. (1994) mentioned that selection of grasses by deer increases after the rainy season. In this study, buffelgrass was the species more preferred by deer. Other grasses such as Botriochloa annulatum, Setaria macrostachya, Aristida sp. and Panicum hallii appeared in traces.

4. Management

implications

Our results indicate that around ten perennial shrub species contributed a major percentage to the annual diets of white-tailed deer in northeastern Mexico. Browse species are important for deer pro-

25 (1996) 141-146

145

viding food and cover. Forbs were a very important part of the diet of white-tailed deer. Managers should strive for a good intermixture of vegetative types to provide a good deer habitat. Deer can coexist with cattle in these regions using the same habitat, as a result of differences in their feeding strategies (Gallina, 1993). Where brush removal is necessary to improve ranges for cattle, important shrub species should be preserved to maintain deer habitat.

Acknowledgements Research was funded by mento Agropecuario of the Leon, Mexico. The authors Escamilla, Jorge Villareal, Javier Carrera.

the Secretaria de FoGoverment of Nuevo wish to thank Albert0 Alejandro Teviiio and

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de investigaci6n 13. Direcci6n General de Estudios de Postgrado. Universidad Aut6noma de Nuevo Le6n. San Nicolls de 10s Garza, N.L., Mtxico, pp. 12-17. Ramfrez, R.G., Sauceda, J.G., Narro, J.A. and Aranda, J., 1993. Preference indices for 3 forage species grazed by Spanish goats on a Semiarid Shrubland in Mexico. J. Appl. Anim. Res., 3: 55-66. Statistical Analysis Systems Institute Inc., 1988. Statistical Analysis System, Version 6. Raleigh, NC, pp. 170-213. Sanders, K.D., Dahl. B.E. and Scott, G., 1980. Bite-count vs. fecal analysis for range diets. J. Range Manage., 33: 146-149. Sparks, D.R. and Malechek, J.C., 1968. Estimating percentage dry weight in diets using a microscopic technique. J. Range Manage., 21: 264-265.

Steel, R.G.D. and Torrie, J.H., 1980. Principles and Procedures of Statistics: A Biometrical Approach. McGraw-Hill, Tokyo, pp. 235-270. Vavra, M., Rice, R.W. and Hansen, R.M., 1978. A comparison of esophageal fistula and fecal material to determine steer diets. J. Range Manage., 39: 699-704. Warren, L.E., Veckerts, D.N., Shelton, M. and Chamrad, A.D., 1984. Spanish goat diets in a mixed-brush rangeland in the South Texas Plains. J. Range Manage., 37: 340-345. Yantis, J.H., Frentress, CD., Daniel, W.S. and Veteto, A.H., 1983. Deer management in the Post Oak Belt. Texas Parks and Wildlife Department, Wildlife Division, P.W.D. Bull. 7000-96, TX, pp. 5-7.