Geology topics

Kelly J. Iknayan

Publications and source records attributed to Kelly J. Iknayan.

3 recordsLinked to original sources

USGS2016

Incorporating imperfect detection into joint models of communites: A response to Warton et al.

Warton et al. [1] advance community ecology by describing a statistical framework that can jointly model abundances (or distributions) across many taxa to quantify how community properties respond to environmental variables. This framework specifies the effects of both measured and unmeasured (latent) variables on the abundance (or occurrence) of each species. Latent variables are random effects that capture the effects of both missing environmental predictors and correlations in parameter values among different species. As presented in Warton et al. , however, the joint modeling framework fails to account for the common problem of detection or measurement errors that always accompany field sampling of abundance or occupancy, and are well known to obscure species- and community-level inferences.

Trends in Ecology and Evolution↗

USGS2013

The effects of force-fledging and premature fledging on the survival of nestling songbirds

Despite the broad consensus that force-fledging of nestling songbirds lowers their probability of survival and therefore should be generally avoided by researchers, that presumption has not been tested. We used radiotelemetry to monitor the survival of fledglings of Ovenbirds Seiurus aurocapilla and Golden-winged Warblers Vermivora chrysoptera that we unintentionally force-fledged (i.e. nestlings left the nest in response to our research activities at typical fledging age), that fledged prematurely (i.e. nestlings left the nest earlier than typical fledging age), and that fledged independently of our activities. Force-fledged Ovenbirds experienced significantly higher survival than those that fledged independent of our activities, and prematurely fledged Ovenbirds had a similarly high survival to those that force-fledged at typical fledging age. We observed a similar, though not statistically significant, pattern in Golden-winged Warbler fledgling survival. Our results suggest that investigator-induced force-fledging of nestlings, even when deemed premature, does not necessarily result in reduced fledgling survival in these species. Instead, our results suggest that a propensity or ability to fledge in response to disturbance may be a predictor of a higher probability of fledgling survival.

Ibis↗

USGS2012

2011 Kiwikiu (Maui Parrotbill) and Maui 'Alauahio abundance estimates and the effect of sampling effort on power to detect a trend

The Kiwikiu ( Pseudonestor xanthophrys ), also called the Maui Parrotbill, is an endangered, forest bird found only in high elevation, wet forest of the eastern portion of Maui Island. Recent surveys, conducted at five year intervals, have revealed wide variation in abundance estimates (Camp et al. 2009). Effective management and conservation requires accurate estimates of abundance, which is difficult for rare species such as the Kiwikiu because low density leads to few observations, resulting in low sample size and high uncertainty in abundance estimates. In addition to being rare, they occur in remote, difficult to access terrain, which makes them difficult to detect and further reduces the accuracy of counts. The Maui `Alauahio ( Paroreomyza montana ), sometimes called the Maui Creeper, historically occupied the entire island of Maui (Gorresen et al. 2009). It has since been extirpated from much of its original habitat and now occurs in forested areas of East Maui where its habitat overlaps with that of the Kiwikiu. Though they share the same habitat, the `Alauahio is much more abundant—by more than two orders of magnitude—and occurs over a wider range than the Kiwikiu. Both species appear to have no statistically significant population trend from 1980–2001, but abundance estimates vary widely from survey to survey and have wide uncertainties (Camp et al. 2009). Ideally survey design should result in estimates precise enough to be able to detect significant declines in abundance that may trigger management intervention. We wished to improve the accuracy of Kiwikiu abundance estimates and the ability to detect significant trends in abundance. To that end, in 2011, repeated point count surveys were conducted across the Kiwikiu range, excluding Haleakalā National Park (Figure 1). The increased sampling effort increases sample size and improves the precision of estimates, and repeat samples also allowed us to partition within-year and between-year variation in surveys, increasing the statistical power to detect trends.

Hawaii↗