Laura Scott-Morales

Continued Decline in Geographic Distribution of the Mexican Prairie Dog (Cynomys Mexicanus)

Abstract We assessed the geographic distribution of the Mexican prairie dog (Cynomys mexicanus) by comparing historical reports, data from a 1996 study, and our distribution estimations from 1999. We located 54 active and 22 inactive prairie dog colonies, determined size for each one, and evaluated whether colony size and isolation had an impact on the persistence of colonies and likelihood for recovery. We estimated a current total distribution of 322 km2 within the Mexican states of Nuevo León (234 km2), Coahuila (82 km2), and San Luis Potosí (6 km2). The occupied range of the Mexican prairie dog suffered a 33% reduction from 1996 to 1999 and an overall reduction of 74% when compared with its documented historical range. We found no relationship between isolation and colony size for active colonies, although geographic isolation can result in decreases in the chances of colonies surviving stochastic events. Other challenges for the recovery of this species include the increased rate of habitat loss and deterioration, and landscape desertification factors.

Medicinal plants in the southern region of the State of Nuevo León, México

BackgroundAlthough the flora of the State of Nuevo León is well known, there are few records of ethnobotancial information. An ethnobotanical study was undertaken in order to know the medicinal plants used by people living at the scrublands and oak-pine forest areas in the southern Nuevo León. Collection of plants specimens and interviews were carried out among the people of the municipalities of Aramberri, Galeana, and Zaragoza. Since former studies in the region are scarce, the aim of this work was to record the medicinal species and their uses in the scrublands and oak-pine forest areas, of southern Nuevo León, Mexico, and also to know if there are differences in the number of species and number of uses knowledge by people.MethodsField work was carried out over a 2 years period; useful plants were collected and a total of 105 people from 46 different villages were interviewed. A database was compiled using data collected by means of semi structured interviews. The data were analyzed by means of non-parametric statistics, using goodness-of-fit test (Chi-squared) (number of species known by people of each municipality, number of uses known by people of each municipality), Chi-squared modified to incorporate the Yates Correction (number of species known by people living at scrublands and oak-pine forest); the Kruskall-Wallis test (number of species known by women and men of the three municipalities), and the Spearman’s rank correlation coefficient (age and number of species known, and age and number of uses).ResultsA total of 163 medicinal plant species were recorded in the study area, comprising 108 wild and 55 cultivated plants. A total of 117 species were recorded in the oak-pine forest, and 111 in the scrublands area, a total of 68 were recorded in both areas; 68 medicinal species are used in all three municipalities, 40 wild and 28 cultivated. We documented 235 different medicinal uses. The most common plant parts used for medicinal purposes were found to be leaves (123 species), stems (55), fruits (28), roots (17), and bark (14). No differences were noted in the number of medicinal plant species identified among people, but differences were significant in their knowledge with respect to the number of uses among people of the three municipalities studied; people from both, scrublands and oak-pine forest know similar number of species and number of uses. Men and women of the three different municipalities knew statistically the same number of species and number of uses. There was no correlation between resident’s age and number of species known and resident’s age and number of uses either in Galeana or in Aramberri, but, there was high correlation among these variables in Zaragoza.ConclusionIn southern Nuevo León people use at least 5% of the total State flora as medicinal plants, and most of these species are included in few plant families. Most of medicinal species are wild and indigenous to the region. The two most important major plant communities, scrublands and oak-pine forest provide almost the same number of medicinal species. A third of the medicinal flora recorded are used in all three municipalities, most of them are wild. Leaves, stems and fruits are the plant parts most commonly used for healing, and boiling is the most common method used for this purpose. Men and women from the three municipalities are familiar with nearly the same number of species; however, their knowledge of the number of uses varies significantly. In Galeana and Aramberri there was no correlation between a person’s age and number of species recognized, however, in Zaragoza, there existed a high correlation between these two factors.

Observations on flocking behavior of Worthen's Sparrows (Spizella wortheni) and occurrence in mixed-species flocks

Abstract Worthens Sparrow (Spizella wortheni) is one of the most endangered species in Mexico. Its survival depends on appropriate conservation strategies and reliable information about the species. Our study on winter groups of Worthens Sparrow flocking with other grassland bird species provides preliminary ecological and behavioral information on this species, and its relation to other migratory and resident bird species in La Perforadora Valley, Coahuila, Mexico. We observed flocking associations of Worthens Sparrow with 16 other species. Ochiais Association Coefficient indicated Worthens Sparrow often associated with Vesper Sparrow (Pooecetes gramineus) (0.60), Black-throated Sparrow (Amphispiza bilineata) (0.33), Horned Lark (Eremophila alpestris) (0.27), and Western Bluebird (Sialia mexicana) (0.22). Worthens Sparrow occurred more frequently in mixed than in monospecific flocks in winter. It foraged more frequently on the ground but also searched in shrub stems, branches, and foliage from perches, and at times hawked for flying insects from perches. Most perches were in the shrub stratum, but fences also were used. Worthens Sparrow in mixed-species flocks spent more time in foraging activities than those in monospecific flocks.

WORTHEN'S SPARROW (SPIZELLA WORTHENI) IN THE NORTHERN MEXICAN PLATEAU

Abstract Worthens sparrow (Spizella wortheni) is probably one of the least known sparrows of North America. Its breeding range is uncertain, as there are questionable records from several localities in Mexico and from the type locality near Silver City, New Mexico, in the United States. Currently, the only unquestionable records are from Coahuila and Nuevo León. Here we describe new localities for this species from the state of Nuevo León and confirm already known localities from Coahuila. These new records were gathered during a bird-monitoring program within colonies of the Mexican prairie dog (Cynomys mexicanus) in northeastern Mexico. We surveyed seven grassland areas and recorded Worthens sparrow at four of them; Los Angeles, La Perforadora, La Soledad, and El Guerrero. Our records add more detail to the known distribution of this species and our behavioral observations suggest they breed in all four localities.

Decline in the endemic Mexican prairie dog Cynomys mexicanus : what do we know about extinction risk?

The Mexican prairie dog Cynomys mexicanus is an endemic burrowing rodent with a restricted distribution. Up to 1996 the species experienced a loss of c. 60% of its historical range, and in the last few years a further loss of habitat has occurred, with the current range now covering only 36% of the historical range. In this study we examined the population dynamics of the Mexican prairie dog to determine the relative effects of habitat loss, isolation of remaining colonies, and decreasing habitat quality. We used data on prairie dog numbers in all colonies and demographic data for two colonies to carry out a stochastic population viability analysis. We found differing vital rates, which are presumed to result from differing habitat quality, at two colonies. As small variations of vital rates in the model strongly influenced the extinction risk for small populations, we conclude that habitat quality is important for the small populations. In the model the Los Angeles complex of colonies experienced a low risk of local extinction whereas at the Manantial complex local extinctions were frequent. Scenarios with changes in population sizes had the largest effect on extinction risk. Differing migration scenarios had little impact on extinction risk.

Isolation and characterization of nine microsatellite loci in the endangered Worthen’s Sparrow (Spizella wortheni)

We report the isolation and characterization of nine microsatellite markers from Worthen’s Sparrow (Spizella wortheni), an endangered bird species endemic to northeastern Mexico. We tested the markers in 32 samples of the species collected near Saltillo Coahuila, Mexico. All markers were polymorphic, with 3–31 alleles per locus, and no difference was found between the observed and expected heterozygosity when applying a sequential Bonferroni correction and a table-wide significance level of 0.05. We found no evidence for linkage disequilibrium between the markers and estimated a null allele frequency of 0.00–0.05. The new markers will allow elucidating the genetic structure and life history of Worthen’s Sparrow and guiding conservation efforts for this endangered species.

Reproduction and Behavior of the Mexican Prairie Dog (Cynomys mexicanus)

Abstract We evaluated breeding season and breeding behavior of two populations (Los Angeles and La Perforadora) of the Mexican prairie dog (Cynomys mexicanus) in northeastern Mexico during January–June 2002 and 2003. We observed 18 coteries in each colony. The breeding season began at the end of January and extended into late April for both colonies. Males were sexually active January–March, and females were in estrus in early March. However, 7 and 10 mature females in La Perforadora and Los Angeles, respectively, underwent estrus in mid-February. Gestation lasted from early March to early April, parturition occurred in early April, and weaning occurred in late April. Infanticide was not observed. Mature females and dominant males of each coterie cut fresh vegetation, possibly for construction of the nest inside the burrow. A series of sexual-mounting exercises occurred outside burrows between young of the same coterie. We describe fights that occurred frequently between adults after the young emerged from their burrows.

La liebre amenazada Lepus flavigularis prefiere establecer sus sitios de alimentación y descanso en potreros con presencia de ganado

Lepus flavigularis Wagner 1844 (Tehuantepec jackrabbit), a species endemic to southern Oaxaca in Mexico, and is currently considered as the jackrabbit in greatest danger of extinction worldwide. In the locality of Santa Maria del Mar in Oaxaca, it inhabits open pastures, sharing habitat with domestic cattle ( Bos taurus ). We hypothesize that L. flavigularis prefers to establish its feeding and resting sites in pastures where cattle are present. Understanding interspecific relationships is of great importance to the establishment of appropriate management plans. We record radio-tagged and no radio-tagged jackrabbits that established their resting and feeding sites on pastures with presence and absence of cattle and a compositional analysis of habitat preference was conducted. This paper reports for the first time the preference of L. flavigularis to establish feeding (ʎ = 0.8010, P = 0.0020) and resting sites (ʎ = 0.6605, P = 0.016) in the pasture with the presence of cattle. Selection of these sites could be attributed to the fact that the presence of cattle can function as an alarm system against possible predators, while the cattle grazing could itself promote palatable species of Poaceae that form part of the diet of this leporid. This information is key to the establishment of future management plans for both species and their ecosystem. A long-term study is required in order to determine the feasibility of cattle and jackrabbit cohabitation. We propose that an efficient rotational grazing program, could contribute to the conservation of this jackrabbit population.