Geology topics

Jeffrey Hatfield

Publications and source records attributed to Jeffrey Hatfield.

6 recordsLinked to original sources

USGS2020

Survival of Laysan Teal Anas laysanensis differs among island populations: Role of chronic avian botulism

Monitoring demographic response over time is valuable for understanding population dynamics of endangered species. We quantified the variation in survival patterns for three small isolated island populations of endangered waterfowl in the Hawaiian Archipelago. Laysan Teal Anas laysanensis were individually marked and the fate of 1,150 individuals were followed from different cohorts among the two reintroduced (Kure and Midway Atolls) and the single relict (Laysan Island) populations for time series of 4, 10 and 15 years respectively. We applied a non-parametric Kaplan-Meier estimator to describe variation between the populations in survival for different cohorts. For Laysan Island and Midway Atoll, we used log-rank tests to determine the effects of cohort, island and sex on survival. Birds in the Laysan Island population had significantly higher survival than those in the Midway population, and males had higher survival than females in both populations. The proportion of females surviving at Midway Atoll was 40% lower than for females on Laysan Island at year 5. The oldest bird observed from Laysan Island was at least 15.5 years old and had been ringed as an adult. The Kure Atoll founder cohort ( n = 28) had 100% survival 18 months post-release, but this dropped by 39% during the first avian botulism type C outbreak. Ten of twenty-eight founders and a population of 60–70 birds persisted on Kure Atoll in 2020. We summarised mortality records to generate hypotheses to explain the cause-specific mechanisms driving the observed survival differences. Mortality data showed that the survival differences between islands in Laysan Teal survival was driven by chronic epizootics of avian botulism type C at Midway and Kure Atoll.

Wildfowl↗

USGS2017

How many Laysan Teal Anas laysanensis are on Midway Atoll? Methods for monitoring abundance after reintroduction

Wildlife managers often request a simple approach to monitor the status of species of concern. In response to that need, we used eight years of monitoring data to estimate population size and test the validity of an index for monitoring accurately the abundance of reintroduced, endangered Laysan Teal Anas laysanensis. The population was established at Midway Atoll in the Hawaiian archipelago after 42 wild birds were translocated from Laysan Island during 2004–2005. We fitted 587 birds with unique markers during 2004–2015, recorded 21,309 sightings until March 2016, and conducted standardised survey counts during 2007–2015. A modified Lincoln-Petersen mark-resight estimator and ANCOVA models were used to test the relationship between survey counts, seasonal detectability, and population abundance. Differences were found between the breeding and non-breeding seasons in detection and how maximum counts recorded related to population estimates. The results showed strong, positive correlations between the seasonal maximum counts and population estimates. The ANCOVA models supported the use of standardised bi-monthly counts of unmarked birds as a valid index to monitor trends among years within a season at Midway Atoll. The translocated population increased to 661 adult and juvenile birds (95% CI = 608–714) by 2010, then declined by 38% between 2010 and 2012 after the Toˉhoku Japan earthquake-generated tsunami inundated 41% of the atoll and triggered an Avian Botulism type C Clostridium botulinum outbreak. Following another severe botulism outbreak during 2015, the population experienced a 37% decline. Data indicated that the Midway Atoll population, like the founding Laysan Island population, is susceptible to catastrophic population declines. Consistent standardised monitoring using simple counts, in place of mark-recapture and resightings surveys, can be used to evaluate population status over the long-term. We estimate there were 314–435 Laysan Teal (95% CI for population estimate; point estimate = 375 individuals) at Midway Atoll in 2015; c. 50% of the global population. In comparison, the most recent estimate for numbers on Laysan Island was of 339 individuals in 2012 (95% CI = 265–413). We suggest that this approach can be used to validate a survey index for any marked, reintroduced resident wildlife population.

Wildfowl↗

USGS2015

Simulating range-wide population and breeding habitat dynamics for an endangered woodland warbler in the face of uncertainty

Population viability analyses provide a quantitative approach that seeks to predict the possible future status of a species of interest under different scenarios and, therefore, can be important components of large-scale species’ conservation programs. We created a model and simulated range-wide population and breeding habitat dynamics for an endangered woodland warbler, the golden-cheeked warbler ( Setophaga chrysoparia ). Habitat-transition probabilities were estimated across the warbler's breeding range by combining National Land Cover Database imagery with multistate modeling. Using these estimates, along with recently published demographic estimates, we examined if the species can remain viable into the future given the current conditions. Lastly, we evaluated if protecting a greater amount of habitat would increase the number of warblers that can be supported in the future by systematically increasing the amount of protected habitat and comparing the estimated terminal carrying capacity at the end of 50 years of simulated habitat change. The estimated habitat-transition probabilities supported the hypothesis that habitat transitions are unidirectional, whereby habitat is more likely to diminish than regenerate. The model results indicated population viability could be achieved under current conditions, depending on dispersal. However, there is considerable uncertainty associated with the population projections due to parametric uncertainty. Model results suggested that increasing the amount of protected lands would have a substantial impact on terminal carrying capacities at the end of a 50-year simulation. Notably, this study identifies the need for collecting the data required to estimate demographic parameters in relation to changes in habitat metrics and population density in multiple regions, and highlights the importance of establishing a common definition of what constitutes protected habitat, what management goals are suitable within those protected areas, and a standard operating procedure to identify areas of priority for habitat conservation efforts. Therefore, we suggest future efforts focus on these aspects of golden-cheeked warbler conservation and ecology.

Ecological Modelling↗

USGS2015

Medea genes, handedness and other traits

Medea factors or genes are maternal-effects mechanisms, found in many species, in which the mother's body selectively kills embryos of a certain genotype.Humans have a similar genetic mechanism, the gene RHD which produces Rh-factor involved in blood type.Recently I proposed that RHD acts as a maternal-effects gene that determines handedness (i.e., right handed or non-right handed) in individuals of our species. Here, I argue that RHD functions as a Medea gene as well.The handedness gene (and also RHD itself in some cases) has been implicated in autism spectrum disorders (ASD), bipolar disorder, cerebral laterality (i.e., right-brained or left-brained speech laterality), hair-whorl rotation, schizophrenia, sexual orientation, and speech dyslexia.Identifying the gene or genes that determine handedness or cerebral laterality may help uncover the mechanisms underlying these behavioral phenotypes in our species.A relatively simple test of the handedness hypothesis has been proposed:In a sample of humans for whom handedness has been evaluated, we would need to genotype for RHD by determining whether Rh+ individuals have one or two copies of the dominant allele. If RHD and perhaps also an interaction with RHCE are involved in sexual orientation, it explains how selection could favor a gene or genes which cause some people to become non-heterosexual.The literature on Medea genes provides the explanation:A Medea allele must increase in frequency, sometimes to fixation (i.e., 100% frequency) even if it reduces fecundity (e.g., birth rate).In addition, treatment for RHD maternal-fetal genotype incompatibility, which allows more fetuses to survive to term now, may be one explanation for why ASD appears to be increasing in frequency in some populations, if RHD is indeed the handedness gene, although many other mechanisms have also been suggested. One wonders if bipolar disorder and the other alternative phenotypes are also increasing in frequency.

Journal of Sleep Disorders & Therapy↗

USGS2014

Long-term monitoring of endangered Laysan ducks: Index validation and population estimates 1998–2012

Monitoring endangered wildlife is essential to assessing management or recovery objectives and learning about population status. We tested assumptions of a population index for endangered Laysan duck (or teal; Anas laysanensis ) monitored using mark–resight methods on Laysan Island, Hawai’i. We marked 723 Laysan ducks between 1998 and 2009 and identified seasonal surveys through 2012 that met accuracy and precision criteria for estimating population abundance. Our results provide a 15-y time series of seasonal population estimates at Laysan Island. We found differences in detection among seasons and how observed counts related to population estimates. The highest counts and the strongest relationship between count and population estimates occurred in autumn (September–November). The best autumn surveys yielded population abundance estimates that ranged from 674 (95% CI = 619–730) in 2003 to 339 (95% CI = 265–413) in 2012. A population decline of 42% was observed between 2010 and 2012 after consecutive storms and Japan’s To¯hoku earthquake-generated tsunami in 2011. Our results show positive correlations between the seasonal maximum counts and population estimates from the same date, and support the use of standardized bimonthly counts of unmarked birds as a valid index to monitor trends among years within a season at Laysan Island.

Hawai’i↗

USGS2005

Efficacy of selected coccidiostats in sandhill cranes (Grus canadensis) following challenge

The anticoccidial efficacy of amprolium, clazuril, and monensin were studied in sandhill cranes ( Grus canadensis ) infected with a mixture of Eimeria spp. oocysts. Five groups of four 1-day-old sandhill crane chicks were maintained on a crumbled ration containing no coccidiostat, amprolium at 2.2 ppm, clazuril at 1.1 ppm, clazuril at 5.5 ppm, or monensin at 99 ppm. After 2 wk on their respective feeding regimens, birds in each of the five groups were administered 25 × 10 3 pooled sporulated Eimeria spp. oocysts per os and observed for another 3 wk. A sixth group of four chicks served as nonmedicated, nonchallenged control during the study. Clinical signs and lesions consistent with disseminated visceral coccidiosis were observed in all challenged controls and birds fed amprolium and clazuril. Birds in these groups died 9–10 days after challenge. In contrast, only one monensin-medicated bird had clinical signs of disseminated visceral coccidiosis, and it died 13 days after challenge (DAC). This and an asymptomatic bird that were necropsied at study termination had less-severe gross and microscopic lesions of disseminated visceral coccidiosis. Two of three monensin-treated birds that survived challenge passed from 50 to 500 coccidial oocysts 11 to 18 DAC but were negative at study termination. Of the coccidiostats tested, monensin, at the dietary level of 99 ppm, was the only anticoccidial drug that provided protection against experimentally induced disseminated visceral coccidiosis in sandhill cranes.

Journal of Zoo and Wildlife Medicine↗