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Accurate analysis of trends in densities estimated from survey data depends on selection of a model that fits the data. When such analysis uses data recorded at different times in the same area but from different transects, then the target species' density and spatial heterogeneity become an issue. It is possible, even in the absence of environmental change, that one set of transects may underestimate or overestimate the density entirely on the basis of location. The resulting risk is that the density estimated earlier may falsely indicate a decline or an increase when compared to the densities estimated later. We investigate this problem for trend analysis of two species of endangered Hawaiian birds at Hakalau Forest National Wildlife Refuge, island of Hawaii. Assertions based on Bayesian regression, and accepted by the U.S. Fish and Wildlife Service, purportedly indicate increases in the density of the endangered Hawaii Akepa (Loxops coccineus coccineus) from 1977 to 2007 and of the endangered Hawaii Creeper (Oreomystis mana) from 1987 to 2007. Here we show, at four study sites spanning the south-north axis of the refuge, that capture rates per mist-net hour of both species declined significantly and the 1977 transects used underestimated density because of location. We submit that the main reason for the differences between our piecewise regression and Bayesian regression is the inappropriate use of Bayesian regression. Analysis by the appropriate model indicates that since 2000 all Hawaiian birds at Hakalau Forest National Wildlife Refuge have been declining. [ABSTRACT FROM AUTHOR]

The article presents a study on trend analysis in eight species of Hawaiian forest passerines to determine the difference between the slopes after the environmental change and the slopes estimated before the change using piecewise regression. It says that piecewise regression meets the model's assumption that all the slopes of eight species were positive and negative after the change. The study suggests that piecewise regression can be an appropriate technique in studying environmental change.

Birds have become increasingly prominent in studies focusing on natural populations and their coevolved pathogens or examining populations under environmental stress from novel and emerging infectious diseases. For either type of study, new DNA-based diagnostic tests, using the polymerase chain reaction (PCR), present challenges in detecting the DNA of pathogens, which exist in low copy number compared with DNA of the host. One example comes from studies of avian malaria: conflicting claims are made by different laboratories about the accuracy of tests using various sets of primers and reagents, especially in relation to blood smears and immunological methods. There is little standardization of protocol or performance among laboratories conducting tests, in contrast to studies of human malaria. This review compares the problems of detecting avian malaria with those of detecting human malaria, and shows definitively that the buffer used to store blood samples following collection is associated with the accuracy of the test. Lower accuracy is associated with use of a lysis buffer, which apparently degrades the DNA in the blood sample and contributes to inhibition of PCR reactions. DNA extraction and purification techniques, and optimization of the PCR reaction, do not appear to be alternative explanations for the effect of storage buffer. Nevertheless, the purest DNA in standard concentrations for PCR is required so that different primers, DNA polymerases, and diagnostic tests can be objectively compared. [ABSTRACT FROM AUTHOR]

Hawaiian honeycreepers (Ayes: Drepanidinae) evolved in the absence of mosquito-borne diseases such as avian malaria (Plasmodium spp.). Malaria has been largely responsible for the recent wave of extinctions and endangerment among Hawaiian forest birds, which began by the 1920s. Most honeycreepers, especially endangered species, now persist only in forests above 1500 m elevation, where cool temperatures prevent effective malaria development in mosquitoes. We report here that prevalence of malaria in Hawaiian forest birds at 1900 m on the island of Hawai'i has more than doubled over a decade. This increase was associated with breeding of mosquitoes and warmer summertime air temperatures. We also report direct evidence of tolerance to malaria, and a possible cost of tolerance, in wild native birds. Tolerance is adding to a reservoir of malaria at upper elevations even while vectors are rare and air temperatures are too low for complete development of the parasite in the vector. The data provide a glimpse of how malaria is becoming an emergent infectious disease at upper elevations. [ABSTRACT FROM AUTHOR]