Birds and Influenza H5N1 Virus Movement to and within North America

TOC Summary: Migratory birds are unlikely introductory hosts for this highly pathogenic virus in its present form into North America

Use of Monofilament Line, Reflective Tape, Beach-Balls, and Pyrotechnics for Controlling Grackle Damage to Citrus

The effectiveness of monofilament line, reflective tape, beach-balls and pyrotechnics (propane cannons and shotgun scare shells) in reducing damage to citrus by great-tailed grackles was tested in the lower Rio Grande Valley of southern Texas. Results indicate that these treatments can produce reduction in damage. Whether the treatments are economically advisable for a grower depends on the history of grackle damage to the grove and grove size. Only large amounts of damage in large groves justify costs associated with implementation of these methods

Use of Monofilament Line, Reflective Tape, Beach-Balls, and Pyrotechnics for Controlling Grackle Damage to Citrus

The effectiveness of monofilament line, reflective tape, beach-balls and pyrotechnics (propane cannons and shotgun scare shells) in reducing damage to citrus by great-tailed grackles was tested in the lower Rio Grande Valley of southern Texas. Results indicate that these treatments can produce reduction in damage. Whether the treatments are economically advisable for a grower depends on the history of grackle damage to the grove and grove size. Only large amounts of damage in large groves justify costs associated with implementation of these methods

Decadal changes and delayed avian species losses due to deforestation in the northern Neotropics

How avifauna respond to the long-term loss and fragmentation of tropical forests is a critical issue in biodiversity management. We use data from over 30 years to gain insights into such changes in the northernmost Neotropical rainforest in the Sierra de Los Tuxtlas of southern Veracruz, Mexico. This region has been extensively deforested over the past half-century. The Estación de Biología Tropical Los Tuxtlas, of the Universidad Nacional Autónoma de México (UNAM), protects a 640 ha tract of lowland forest. It became relatively isolated from other forested tracts between 1975 and 1985, but it retains a corridor of forest to more extensive forests at higher elevations on Volcán San Martín. Most deforestation in this area occurred during the 1970s and early 1980s. Forest birds were sampled on the station and surrounding areas using mist nets during eight non-breeding seasons from 1973 to 2004 (though in some seasons netting extended into the local breeding season for some species). Our data suggested extirpations or declines in 12 species of birds subject to capture in mist nets. Six of the eight species no longer present were captured in 1992–95, but not in 2003–2004. Presence/absence data from netting and observational data suggested that another four low-density species also disappeared since sampling began. This indicates a substantial time lag between the loss of habitat and the apparent extirpation of these species. Delayed species loss and the heterogeneous nature of the species affected will be important factors in tropical forest management and conservation

Avian distribution and abundance records for the Sierra de Los Tuxtlas

ABSTRACT.-Between 1973 and 1987 we spent more than 36 months studying birds in the Sierra de Los Tuxtlas, on the Gulf coast of southern Veracruz, Mexico. This area contains the northernmost tropical rainforest in the western hemisphere, and has undergone relatively rapid deforestation in the past three decades. Its avifauna is diverse, consisting of both resident and migratory birds. We recorded 405 species, including 58 that have not been reported from the region before, as well as several that apparently have not been reported for Veracruz. Fully 350 species are documented by specimens; the remaining 55 consist of sight records only. We compare our results with past surveys of Los Tuxtlas and discuss 124 species whose status in the region is affected by our data. Of the 405 species we recorded in Los Tuxtlas, 96 (23.7%) appear on a list of bird species from the northern neotropics thought to be in danger due to tropical deforestation. Received 9 Jan. 1992, accepted 29 April 1992. The Sierra de Los Tuxtlas (hence Los Tuxtlas) is a rugged, mountainous region of volcanic origin, isolated from the Sierr

Blood Parasites in Owls with Conservation Implications for the Spotted Owl (Strix occidentalis)

The three subspecies of Spotted Owl (Northern, Strix occidentalis caurina; California, S. o. occidentalis; and Mexican, S. o. lucida) are all threatened by habitat loss and range expansion of the Barred Owl (S. varia). An unaddressed threat is whether Barred Owls could be a source of novel strains of disease such as avian malaria (Plasmodium spp.) or other blood parasites potentially harmful for Spotted Owls. Although Barred Owls commonly harbor Plasmodium infections, these parasites have not been documented in the Spotted Owl. We screened 111 Spotted Owls, 44 Barred Owls, and 387 owls of nine other species for haemosporidian parasites (Leucocytozoon, Plasmodium, and Haemoproteus spp.). California Spotted Owls had the greatest number of simultaneous multi-species infections (44%). Additionally, sequencing results revealed that the Northern and California Spotted Owl subspecies together had the highest number of Leucocytozoon parasite lineages (n = 17) and unique lineages (n = 12). This high level of sequence diversity is significant because only one Leucocytozoon species (L. danilewskyi) has been accepted as valid among all owls, suggesting that L. danilewskyi is a cryptic species. Furthermore, a Plasmodium parasite was documented in a Northern Spotted Owl for the first time. West Coast Barred Owls had a lower prevalence of infection (15%) when compared to sympatric Spotted Owls (S. o. caurina 52%, S. o. occidentalis 79%) and Barred Owls from the historic range (61%). Consequently, Barred Owls on the West Coast may have a competitive advantage over the potentially immune compromised Spotted Owls

Aves migratorias neárticas en comunidades templadas y tropicales

Nearctic avian migrants in temperate and tropical communities. Poputations of over 300 species of birds that breed in America, north of Mexico, spend a portion of their life cycle in the tropical zone. Studies in Veracruz, Mexico, and elsewhere in the tropics have shown that there is intense intraspecific competition, fidelity to wintering sites, and niche specificity in migrants using these tropical environments. These findings indicate that many migrant populations are as dependent for survival upon tropical communities as upon the temperate or boreal communities in which they breed. However, not only are these communities important to migrants; migrants are also important to the communities, affecting community ecology in a number of subtle but important ways including: pollination, fruiting seasons and dispersal strategies in plants; invertebrate hatching periods; parasite life cycles and breeding cycles among resident frugivores, insectivores and carnivores. Migratory birds from a fragile link between ecosystems thousands of kilomemeters apart. Through these species the effects of habitat misuse in one area can be felt throughout many widely separated parts of the hemisphere. The ecology of the migrant symbolizes the need for international cooperation in matters of conservation

Effects of Grackle Damage Control Techniques in Citrus on Nesting Success of Non-Target Species

Several techniques were tested to reduce the damage caused by great-tailed grackles to citrus in the lower Rio Grande Valley of southern Texas: monofilament line, eyespot balloons, pyrotechnics, and grackle nest removal. Ten species were found nesting in the treated groves, but only the mourning dove, white-winged dove, and great-tailed grackle in significant numbers. Nesting success was not reduced significantly by any treatment but observations indicate that cannon treatments are likely to have a negative impact on overall nesting success for several species

Seasonal Effects on Control Methods for the Great-Tailed Grackle

Efficiency of methods used to control damage to citrus fruit by great-tailed grackles was found to vary considerably from season to season. From April - July, the birds congregated in small breeding colonies where they were susceptible to baiting and poisoning. From August - October, the birds could be baited in to and poisoned at watering sites. Intensive shooting and use of pyrotechnics were also used successfully at this time of year to control damage at groves with high grackle concentrations. From late October - March, birds moved over wide areas each day, and were easily frightened from groves by pyrotechnics and shooting. No single method is available at present to control the entire population or to protect a given grove through all seasons