Anas Diazi Research Articles

Characteristics of the Habitat and Population Densities of the Mexican Duck (Anas diazi) in the Plateau of Zacatecas, Mexico

The Mexican duck (Anas diazi) is an endemic species that has been categorized as threatened because of its practice of living in small populations and because of the condition of the wetlands in which it occurs. Therefore, the preference for wetlands by the species is influenced by the adjacent vegetation composition found in the Mexican Central Plateau in the state of Zacatecas. The inclination of the duck towards the wetlands in relation to the aquatic and adjacent vegetation structure was evaluated in the studied area. Seven wetlands were selected and distinguished by the presence of a population of the species. Vegetation was analyzed in three strata—tree layer, shrub layer and herb layer—and the population of the Mexican duck was calculated through direct counting in each wetland. The results determined a significantly larger number of individuals in artificial wetlands than in lakes. The wetlands’ adjacent vegetation is constituted by graminean and shrub species, with an aquatic vegetation cover. The non-parametric Mann–Whitney U test showed a significant difference between the counts of ducks and the physical structure of wetlands in the examined area. The data obtained indicate that the Mexican Duck occurs mainly in artificial wetlands with mainly graminean vegetation and aquatic plant cover; similar characteristics to those previously described for dabbling ducks.

Human-Induced Range Expansions Result in a Recent Hybrid Zone between Sister Species of Ducks.

Landscapes are consistently under pressure from human-induced ecological change, often resulting in shifting species distributions. For some species, changing the geographical breadth of their niche space results in matching range shifts to regions other than those in which they are formally found. In this study, we employ a population genomics approach to assess potential conservation issues arising from purported range expansions into the south Texas Brush Country of two sister species of ducks: mottled (Anas fulvigula) and Mexican (Anas diazi) ducks. Specifically, despite being non-migratory, both species are increasingly being recorded outside their formal ranges, with the northeastward and westward expansions of Mexican and mottled ducks, respectively, perhaps resulting in secondary contact today. We assessed genetic ancestry using thousands of autosomal loci across the ranges of both species, as well as sampled Mexican- and mottled-like ducks from across overlapping regions of south Texas. First, we confirm that both species are indeed expanding their ranges, with genetically pure Western Gulf Coast mottled ducks confirmed as far west as La Salle county, Texas, while Mexican ducks recorded across Texas counties near the USA-Mexico border. Importantly, the first confirmed Mexican × mottled duck hybrids were found in between these regions, which likely represents a recently established contact zone that is, on average, ~100 km wide. We posit that climate- and land use-associated changes, including coastal habitat degradation coupled with increases in artificial habitats in the interior regions of Texas, are facilitating these range expansions. Consequently, continued monitoring of this recent contact event can serve to understand species' responses in the Anthropocene, but it can also be used to revise operational survey areas for mottled ducks.

Evolutionary and ecological drivers of local adaptation and speciation in a North American avian species complex.

Throughout the speciation process, genomic divergence can be differentially impacted by selective pressures, as well as gene flow and genetic drift. Disentangling the effects of these evolutionary mechanisms remains challenging, especially for nonmodel organisms. Accounting for complex evolutionary histories and contemporary population structure often requires sufficient sample sizes, for which the expense of full genomes remains prohibitive. Here, we demonstrate the utility of partial-genome sequence data for range-wide samples to shed light into the divergence process of two closely related ducks, the Mexican duck (Anas diazi) and mallard (A. platyrhynchos). We determine the role of selective and neutral processes during speciation of Mexican ducks by integrating evolutionary and demographic modelling with genotype-environment and genotype-phenotype association testing. First, evolutionary models and demographic analyses support the hypothesis that Mexican ducks originally diverged ~300,000years ago in climate refugia arising during a glacial period in southwest North America, and that subsequent environmental selective pressures played a key role in divergence. Mexican ducks then showed cyclical demographic patterns that probably reflected repeated range expansions and contractions, along with bouts of gene flow with mallards during glacial cycles. Finally, we provide evidence that sexual selection acted on several phenotypic traits as a co-evolutionary process, facilitating the development of reproductive barriers that initially arose due to strong ecological selection. More broadly, this work reveals that the genomic and phenotypic patterns observed across species complexes are the result of myriad factors that contribute in dynamic ways to the evolutionary trajectories of a lineage.

A PRÉCIS AND CHECKLIST OF HELMINTH PARASITES FOR 14 SPECIES OF WATERFOWL FROM THE CHIHUAHUA DESERT IN THE UNITED STATES AND MEXICO.

A précis of helminth parasite infections and a host-parasite checklist are presented for the following 14 species of waterfowl from the Chihuahua Desert in the United States and Mexico: Chen rossii, Chen caerulescens, Anas platyrhynchos, Anas diazi, Anas acuta, Anas strepera, Anas americana, Anas clypeata, Anas cyanoptera, Anas crecca, Bucephala albeola, Oxyura jamaicensis, Fulica americana, and Podiceps nigricollis. There was a total of 127 species of helminths recovered from the 14 species of waterfowl. Total abundance, which included data available for 12 species of waterfowl, was 134,202 (mean = 11,184, median = 1,376, and 95% confidence limit [CL] = 14,485). Mean species richness ranged from 1.5 in Ross's goose, C. rossii, to 4.3 in the bufflehead, B. albeola. Host mean abundance ranged from 7.5 in the Mexican duck, A. diazi, and green-winged teal, A. crecca, to a high of 811 for the ruddy duck, O. jamaicensis. Ninety-one percent of the helminth species were generalists. Most specialists were associated with the American coot, F. americana (7), and the eared grebe, P. nigricollis (5). Percent helminth species contribution was cestodes 45%, nematodes 25%, trematodes 22%, and acanthocephalans 8%. The most commonly occurring helminth species among the 14 host species were the trematode Notocotylus attenuatus (12), the cestode Cloacotaenia megalops (10), the acanthocephalan Corynosoma constrictum (9), and the nematode Capillaria anatis (6). Low ingestion of invertebrates may have contributed to the lower number of helminth species and abundance in wintering and spring dabbling ducks (Anatini). Wild dabbling ducks ranging in age from 6 mo to 8 yr and 8 mo were infected with helminth parasites. Helminth parasite data from resident and nesting hosts and pre-fledged young birds indicated as many as 43 helminth life cycles may be occurring in the Chihuahua Desert. Host-parasite species checklists are included.

Nevada Bird Records Committee Report for 2019–2020

In 2019 and 2020, the Nevada Bird Records Committee reviewed 79 reports from the period 4 November 1955 to 23 October 2020. Seventy of them were endorsed. It added three species to the state checklist, the Field Sparrow (Spizella pusilla), Mexican Duck (Anas diazi), and Pine Warbler (Setophaga pinus). Two of those (the Field Sparrow and Pine Warbler) were added to the review list. The Mexican Duck was elevated from subspecies to species status, and it, along with six other species, were removed from the review list. We also continued reviewing records that precede the committee’s establishment in 1994.

Molecular identification and phylogenetic characterization of influenza A virus at a wildlife–livestock interface in Mexico

Influenza A virus (IAV) outbreaks constitute a constant threat to public health and pose a remarkable impact on socio-economic systems worldwide. Interactions between wild and domestic birds, humans and swine can lead to spillover events. Backyard livestock systems in proximity to wetlands represent high-risk areas for viral spread. However, some gaps remain in our knowledge of IAV transmission at the wildlife-livestock interface in Mexico. Hence, the study aimed at molecular identification and phylogenetic characterization of IAV in the wild duck-backyard livestock interface at a wetland of Mexico. A total of 875 animals were tested by real-time RT-PCR (qRT-PCR). We detected IAV in 3.68% of the wild ducks sampled during the winter season 2016-2017. Nonetheless, the samples obtained from backyard poultry and swine tested negative. The highest IAV frequency (11.10%) was found in the Mexican duck (Anas diazi). Subtypes H1N1, H3N2 and H5N2 were detected. Phylogenetic analyses revealed that IAV detected in wild birds from the Lerma wetlands was mostly related to swine and poultry IAV strains previously isolated in the United States and Mexico. Except, the UIFMVZ377/H5N2 related to North American waterbirds. In conclusion, the co-circulation of three IAV subtypes in wild ducks close to backyard farms in Mexico, as well as the local identification of influenza viruses genetically related to Mexican and North American IAV strains, highlights the importance of the Lerma marshes for influenza surveillance given the close interaction among wild birds, poultry, pigs and humans.

Phylogenetic characterization of a reassortant H5N2 influenza A virus from a resident Mexican duck (Anas diazi)

Congregation of different migratory and resident bird species on aquatic ecosystems during winter migration increases contact rates and enhances influenza A virus (IAV) transmission. However, scarce research has been focused on the resident bird's contribution to the viral ecology at a local scale. The Mexican duck (Anas diazi) is an endemic endangered anatid from Mexico. This resident species shares aquatic habitats with migratory birds in the wetlands of Central Mexico. Therefore, here we describe the phylogenetic analysis of an IAV (A/Mexican duck/EstadodeMexico; Lerma/UIFMVZ377/2016(H5N2)) isolated in this species, during spatiotemporal concurrence with migratory anatids in the winter season. All eight gene sequences were obtained by nextgeneration sequencing. Maximum Likelihood trees were constructed using MEGA-X, with General Time Reversible + Invariant (GTR+I), Subtree Pruning and Regrafting (SPR) heuristic method, and 1000 bootstrap replicates. Similarities with six different IAV subtypes were observed through a BLAST search: H6N5, H7N7, H5N2, H4N6, H9N2, and H11N9, detected in wild ducks during 2015 in the Pacific, Central and Mississippi flyways stop sites across the United States of America and Canada. The molecular identification of this reassortant H5N2 IAV highlights the importance of resident species as a reservoir host and its potential participation in the maintenance and transmission of IAV in wetlands surrounded by rural areas.

Nidos y nidadas de pato mexicano (Anas diazi) en Pénjamo, Guanajuato, México

Se describen siete nidos de pato mexicano o garbancero (Anas diazi) de Pénjamo, Guanajuato, México. La distancia del nido al agua más cercana fue de 100 m a 800 m; la distancia al cuerpo de agua permanente más cercano fue de 150 m a 1500 m; la altura de la vegetación en el sitio de anidación fue de 50 cm a 130 cm. Los nidos fueron predominantemente de tipo copa baja-lateral. Las dimensiones externas fueron 17 cm - 36 cm × 9 cm - 20 cm. El material primario de construcción fue de pata de trigo y de manera secundaria Bouteloua-sorgo. Se encontraron de 1 a 6 huevos por nido, incluyendo posturas viables (n = 2), saqueadas (n = 1), abandonadas (n = 2) y exitosas (n = 1). Las nidadas observadas (n= 6) tuvieron entre 3 crías y 9 crías, encontradas sobre y hasta 400 m del agua. Dada la escasez de información disponible para la especie, estos resultados contribuyen a su conocimiento en el área más importante de distribución.

Mexican Duck (Anas diazi)

Mexican Duck (Anas diazi)

First molecular identification of Australapatemon burti (Miller, 1923) (Trematoda: Digenea: Strigeidae) from an intermediate host Radix labiata (Rossmaessler) (Gastropoda: Lymnaeidae) in Europe.

The strigeid digenean species Australapatemon burti (Miller, 1923) (Trematoda: Digenea: Strigeidae) was originally described from North America, but recorded in the Neotropical region (Drago et al. 2007; Hernández-Mena et al. 2014; Blasco-Costa et al. 2016) and in Central Europe (Faltýnková et al. 2007). In Europe, this species is rare, and there is not much information about its range (Faltýnková et al. 2007; Soldánová et al. 2012). Australapatemon burti has a complex life cycle with three larval stages, two of which (sporocyst and cercaria) use several species of freshwater snails, and the third stage (metacercaria) use non-specific host hirudineans (Dubois 1968; Davies & Ostrowski de Núñez 2012; Blasco-Costa et al. 2016). Adult flukes are parasitic in the intenstines of various waterfowl species, such as ducks and swans (Drago et al. 2007; Hernández-Mena et al. 2014). Currently, the molecular data on this parasite species includes only nucleotide sequences of four adult specimens from Mexico (Hernández-Mena et al. 2014). Their hosts were Mexican duck, Anas diazi Ridgway, American Wigeon, Anas americana Gmelin, Cinnamon Teal, Anas cyanoptera Vieillot, and Ruddy Duck, Oxyura jamaicensis (Gmelin) (Anserformes: Anatidae).

Prevalence of Toxoplasma gondii Infection in Wild Birds in Durango, Mexico

There is a lack of information concerning the prevalence of Toxoplasma gondii infection in wild birds in Mexico. In the present study, serum samples and tissues from 653 birds from Durango State, Mexico, were evaluated for T. gondii infection. Antibodies to T. gondii (modified agglutination test, titer 1∶25 or higher) were found in 17 (2.6%) of the 653 birds, including 1 of 2 curve-billed thrashers (Toxostoma curvirostre), 2 (1 Anas platyrhynchos, 1 Anas diazi) of 4 ducks, 1 of 2 eagles (Aquila sp.), 5 (27.8%) of 18 great-tailed grackles (Quiscalus mexicanus), 7 (1.3%) of 521 rock pigeons (Columba livia), and 1 (14.3%) of 7 quail (Coturnix coturnix). The seroprevalence of T. gondii infection in birds captured in a park outside the city zoo (11.6%, 8/69) was significantly higher than that found in birds from other regions (1.5%, 9/584, OR = 8.38; 95% CI: 2.82-24.77; P = 0.0001). Brains and hearts of 23 birds (17 seropositive, 6 seronegative) were bioassayed in mice for the isolation of T. gondii . Viable T. gondii was isolated from 1 of 7 seropositive pigeons. The DNA obtained from the T. gondii isolate from the pigeon was genotyped using the PCR-RFLP typing using 11 markers (B1, SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) and revealed an atypical genotype. This is the first report of T. gondii infection in great-tailed grackles, the Mexican duck, and curved-billed thrashers and the first survey of wild birds in Mexico.

Uso y selección de embalses por el pato mexicano (Anas diazi) en la región del llano, Aguascalientes-Jalisco, México

Se registró, entre septiembre de 1994 y marzo de 1995, el uso de embalses por el pato mexicano (Anas diazi Ridway, 1886) en la región de El Llano, entre Aguascalientes y Jalisco en México. El objetivo de este estudio fue determinar cuáles embalses son seleccionados o evitados por esta especie, con base en un análisis de uso-disponibilidad de cuerpos de agua. Los resultados sugieren un uso superior al esperado de los bordos, los cuales se utilizan para almacenar agua que se extrae por bombeo para irrigación, durante el otoño y parte del invierno. Este tipo de almacenamiento de agua puede ser importante para la continuidad del ciclo vital del único anátido residente del Altiplano mexicano. La evaluación e identificación de los cuerpos de agua que son utilizados por encima de su disponibilidad, permitiría proponer estrategias para la conservación y aprovechamiento sostenible de esta especie.

Wildfowl population trends in Mexico, 1961–2000: a basis for conservation planning

We analysed population trends of 24 wildfowl species in Mexico. Wildfowl numbers peaked during the early 1980s; lowest counts were recorded in 1997. Total wildfowl numbers (all species combined) and duck numbers (duck species combined) showed significant short-term (1981–2000) declines, while geese (goose species combined) showed a significant long-term (1961–2000) increase. Six wildfowl species suffered significant long-term declines, while four showed increases. During 1981–2000, 11 species declined, but none had significant increases. Redhead ( Aythya americana), Mexican duck ( Anas diazi), northern pintail ( A. acuta) and black brant ( Branta bernicla nigricans) should be given high conservation priority because of the high proportions of their North American populations in Mexico. Declining numbers of the later two species should trigger further investigation into the possibility of assigning them legal protection status. Other species with apparent declines in numbers should also be more closely monitored. For setting hunting limits in the country, the population status of each species should be accounted for, as well as the condition of breeding populations the previous spring. Other species with poor data or combined counts should be targeted for basic population studies. We suggest that the mid-winter counts be expanded to cover non-surveyed areas and conducted every year to more precisely detect wildfowl population change. Integrated to a site-selection analysis, the information presented here can provide the basis for a wildfowl conservation strategy in Mexico.

Population trends and priority conservation sites for Mexican Duck Anas diazi

Little is known about Mexican Duck Anas diazi biology and populations. We analyse long-term (1960–2000) trends of Mexican Duck numbers in Mexico and employ contemporary count data (1991–2000) from the U.S. Fish and Wildlife Service midwinter surveys to identify key sites for conservation using a complementarity approach. The overall Mexican Duck population showed a significant long-term increase of 2.5% per year, with large fluctuations throughout the study period. The Northern highlands population increased at an annual rate of 7.7%, while the Central highlands population showed no significant long-term trend. During the last decade, counts in both the Northern and Central highlands exhibited no significant change. At the site level, significant long-term increases occurred in four localities in the Northern highlands (Laguna Bab�cora +13.9% annually, Laguna Bustillos +25.9%, Laguna Mexicanos +20.4% and Laguna Santiaguillo +16.9%) and in three localities in the Central highlands (Languillo +15.3% annually, Presa Solís +8.9%, Zacapu +13.4%). Two sites in the Central highlands showed significant declines, in the long term (Lago de Chapala, -5.2% per year) and during the last decade (Lerma, -11.8% per year). The Northern highlands held 16% and the Central highlands 84% of the Mexican Duck population in the period 1960–2000; during the last decade, these figures were 31% and 69%, respectively. A set of priority sites for conservation of the Mexican Duck was identified, consisting of 15 sites holding more than 70% of the midwinter Mexican Duck counts in Mexico. Ten sites from the priority set also qualify for designation as wetlands of international importance under the Ramsar Convention on Wetlands, by holding ≥ 1% of the estimated population. Four of the priority sites are in the Northern highlands and 11 in the Central highlands, of which eight are distributed along the Rio Lerma drainage. The most urgent actions that need to be undertaken are to estimate the current minimum population size in Mexico; to establish a programme for monitoring populations in the priority sites, especially those located within the highly degraded Rio Lerma drainage; and to determine the most feasible management actions for the species, concentrating efforts around the priority sites.

Blood Parasites of Some Birds from Northeastern Mexico

A total of 196 birds of 31 species from 15 families from northeastern Mexico was examined for blood parasites; 25 birds (12.8%) of 11 species harbored 1 or more species of hematozoans. Species of Haemoproteus accounted for half of the total infections encountered. Leucocytozoon simondi was found in 2 Mexico ducks (Anas diazi) and this represents the first record of the transmission of this parasite in Mexico. The results of this survey were compared with those obtained nearly 50 yr ago from a survey of birds from the same general area; prevalence in both samples was similar, despite the change to a more agricultural environment over this period.

Evolutionary Relationships among the North American Mallards

THIS study is the report of an attempt to understand the evolutionary relationships existing within a group of mallardlike ducks native to North America. The group includes the Common Mallard, Anas platyrhynchos platyrhynchos L.; the Black Duck, Anas rubripes Brewster; the Florida Duck, Anas fulvigula fulvigula Ridgway; the Mottled Duck, Anas fulvigitla niiaculosa Sennett; the Mexican Duck, Anas diazi diazi Ridgway; and the New Mexican duck, Anas diazi novimexicana Huber. All but one of these (the Common Mallard) are restricted to North America, and all these American forms possess a sexually nondimorphic plumage. In all other respects they are extremely similar to the Common Mallard, and a study of their relationships to this form was believed possibly to provide an instructive example of speciation.