Geology topics

Philip T. Patton

Publications and source records attributed to Philip T. Patton.

2 recordsLinked to original sources

USGS2026

Modeling two decades of elevational change in endemic bird densities in Hawaiʻi’s Kaʻū Rainforest

Protected areas are vital to the recovery of endangered species. Of the 24 remaining endemic passerines in Hawaiʻi, 16 species are endangered or critically endangered. Yet protected areas in the archipelago are changing as a result of climate change and biological invasions. For example, the non-native southern house mosquito ( Culex quinquefasciatus ), the primary vector of avian malaria ( Plasmodium relictum ), has been encroaching upward as higher elevations warm. How the ranges of endemic birds have also shifted their range upward in the Kaʻū Rainforest, the largest native forest on the Island of Hawaiʻi, is not well understood. We used hierarchical distance sampling to characterize how population density has changed from 2002 to 2024 for eight endemic bird species in the Kaʻū Rainforest. For five species, the most parsimonious model included an interaction between year and a quadratic elevation effect. Species that were most common at lower elevations in 2002, e.g., ʻApapane ( Himatione sanguinea ), tended to be most common at mid- elevations by 2024. Species that were already most common at higher elevations, such as ʻIʻiwi ( Drepanis coccinea ) and Hawaiʻi ʻĀkepa ( Loxops coccineus ), tended to decline in density. For example, ʻIʻiwi density at 1,530 m declined from 3.31 birds per ha (95% confidence interval [CI]: 2.67-4.11) to 1.34 birds per ha (95% CI: 1.05-1.71), and Hawaiʻi ʻĀkepa were completely extirpated from elevations below 1,530 m by 2024. Our results demonstrate how the elevational ranges of endemic species have shifted in response to climate change, biological invasions, and habitat degradation. Translating these results into conservation measures may require a more thorough investigation of the causal mechanisms of these range shifts with finer scale habitat data, under the same hierarchical modeling framework.

BioRxiv↗

USGS2022

Modeling and estimating co-occurrence between the invasive Shiny Cowbird and its Puerto Rican hosts

Invasive species threaten island biodiversity globally. For example, the Shiny Cowbird ( Molothrus bonariensis ) parasitizes many of Puerto Rico’s endemic species, particularly in the open forests in the island’s southwest. Less is known, however, about cowbird parasitism in the agro-ecological highlands, which contain a patchwork of forests, shaded-coffee plantations, and coffee farms without shade. In this paper, we estimated co-occurrence rates, a potential indicator of parasitism rates, between the cowbird and four host species across these three land uses, hypothesizing that cowbirds would most likely co-occur with their hosts in shaded-coffee farms. We also hypothesized that the presence of host species would increase the probability of cowbird occurrence. To investigate these hypotheses, we developed three Bayesian hierarchical occupancy models: one where the hosts and parasite occurred independently, one that used the latent host species richness as a predictor of cowbird occurrence, and one that used each latent host occurrence state as predictors. These methods addressed observation errors and appropriately propagated error to our predictions of co-occurrence rates. We selected the best performing model using WAIC, then used it to predict co-occurrence rates. While there was some evidence that host species richness increased the probability of cowbirds, the parsimonious model assumed no interaction. With this model, we found that cowbirds were more likely to overlap with certain hosts in shaded-coffee plantations. This may suggest increased parasitism at these plantations, potentially presenting challenges for managers who advocate for shade restoration to gain ecological services such as biodiversity conservation.

Biological Invasions↗