A Feasibility Study of Using Unmanned Aerial Vehicles to Survey Avian Abundance by Using Audio Recording

Roadside counts are commonly used to assess songbird abundance, but they result in oversampling habitat edges and underrepresenting core habitats, areas of steep terrain, and wetlands. Accessing off-road habitats can be logistical challenging and time-consuming, resulting in low survey efficiency. Aerial ecological surveys, using unmanned aerial vehicles (UAVs, or drones) have already proven to be valuable in wildlife monitoring. Previous studies have used photography or videography to provide permanent documentation of wildlife surveys through low altitude aerial imagery. A significant advantage of UAVs over manned aircraft is their greater safety and lower costs. We propose that UAVs can also be used to conduct audio surveys of vocal species. Here, we report on experiments to test the feasibility of using UAVs to conduct point counts of songbirds. To establish the detection radius of bird songs recorded with a microphone attached to a UAV (DJI Phantom 2.0), recordings of the songs of five regionally abundant bird species (Wood Thrush, Eastern Towhee, Song Sparrow, Chipping Sparrow, and Eastern Meadowlark) were broadcast at distances of up to 140m from the UAV, which was flown at three altitudes (20m, 40m, and 60m). We found that detection rates and radial detection distances of the broadcasts did not differ with UAV altitude. Bird recordings were clearly audible at radial distances of 60m. We conclude that it is feasible to use UAVs to conduct aerial point counts that are comparable with traditional terrestrial bird point counts, and describe additional field experimentation needed to refine our survey protocols

Spatial and Temporal Relationships Between Forest Bird Declines and Prevalence of the Hemlock Woolly Adelgid in the Northeastern United States

The eastern hemlock (Tsuga canadensis) is a vital foundation tree species throughout the eastern United States, providing essential structural diversity and habitat for more than 120 different animal species. Within the past few decades, T. canadensis has undergone significant declines that are largely associated with the hemlock woolly adelgid (HWA; Adelges tsugae), an exotic, aphid-like insect native to East Asia. From the 1970s to present day, the HWA has spread throughout southern New England, large portions of the Mid-Atlantic region, and parts of Tennessee and the Carolinas. Research has shown that loss of the eastern hemlock is drastically altering forest community structures, potentially impacting a wide variety of forest fauna, including avian populations strongly associated with hemlock forests. Here we present research investigating the correlation between HWA prevalence and recent declines of hemlock-associated forest birds in the Eastern US. We analyzed bird population trends data from the North American Breeding Bird Survey (BBS), US Forest Service HWA data, and land cover data to analyze the population trends of hemlock-associated and forest generalist species in association with the arrival of HWA, taking hemlock density into account. We found a significant correlation between the timing of HWA arrival and declines of conifer forest specialist birds. The Black-throated Green Warbler and the Blue-headed Vireo exhibited significant decline along survey routes after HWA arrival. Populations of some forest generalists (Tufted Titmouse, White-Breasted Nuthatch) were unaffected and continued to increase linearly, while others (Red-Eyed Vireo, Ovenbird) showed minor decrease in population

The Feasibility of Counting Songbirds Using Unmanned Aerial Vehicles

Obtaining unbiased survey data for vocal bird species is inherently challenging due to observer biases, habitat coverage biases, and logistical constraints. We propose that combining bioacoustic monitoring with unmanned aerial vehicle (UAV) technology could reduce some of these biases and allow bird surveys to be conducted in less accessible areas. We tested the feasibility of the UAV approach to songbird surveys using a low-cost quadcopter with a simple, lightweight recorder suspended 8 m below the vehicle. In a field experiment using playback of bird recordings, we found that small variations in UAV altitude (it hovered at 28, 48, and 68 m) didn\u27t have a significant effect on detections by the recorder attached to the UAV, and we found that the detection radius of our equipment was comparable with detection radii of standard point counts. We then field tested our equipment, comparing songbird detections from our UAV-mounted recorder with standard point-count data from 51 count stations. We found that the number of birds per point on UAV counts was comparable with standard counts for most species, but there were significant underestimates for some—specifically, issues of song masking for a species with a low-frequency song, the Mourning Dove (Zenaida macroura); and underestimation of the abundance of a species that was found in very high densities, the Gray Catbird (Dumetella carolinensis). Species richness was lower on UAV counts (mean = 5.6 species point−1) than on standard counts (8.3 species point−1), but only slightly lower than on standard counts if nonaudible detections are omitted (6.5 species point−1). Excessive UAV noise is a major hurdle to using UAVs for bioacoustic monitoring, but we are optimistic that technological innovations to reduce motor and rotor noise will significantly reduce this issue. We conclude that UAV-based bioacoustic monitoring holds great promise, and we urge other researchers to consider further experimentation to refine techniques

Online Mapping Tools for Geolocating Amish Settlements

This technical note demonstrates the value of using online mapping tools as a method of geolocating Amish settlements. Primarily using freely available Bing and Google maps and published lists of the addresses of Amish ministers, we geolocated 1,362 Amish households in Ohio and 1,203 in Pennsylvania, representing about 10% of Amish households in those states. From these data we were able to derive a population density map of the Amish across Ohio and Pennsylvania. We caution that our map is merely a model and based on several assumptions, but the product is a finer resolution map of Amish distribution than has previously been published. We add that the locations of Amish schools provide another promising avenue for geolocation of Amish settlements, but we were not able to locate sufficiently comprehensive lists to include them in our analysis

Estimation of a 3D motion field from a multi-camera array using a multiresolution Gaussian mixture model

The problem of modelling geometry for video based rendering has been much studied in recent years, due to the growing interest in 'free viewpoint' video and similar applications. Common approaches fall into two categories: those which approximate surfaces from dense depth maps obtained by generalisations of stereopsis and those which employ an explicit geometric representation such as a mesh. While the former have generality with respect to geometry, they are limited in terms of viewpoint; the latter, on the other hand, sacrifice generality of geometry for freedom to pick an arbitary viewpoint. The purpose of the work reported here is to bridge this gap in object representation, by employing a stochastic model of object structure: a multiresolution Gaussian mixture. Estimation of the model and tracking it through time from multiple cameras is achieved by a multiresolution stochastic simulation. After a brief outline of the method, its use in modelling human motion using data from local and other sources is presented to illustrate its effectiveness compared to the current state of the art

QR Codes in the Library: Are They Worth the Effort? Analysis of a QR Code Pilot Project

The literature is filled with potential uses for Quick Response (QR) codes in the library. Setting, but few library QR code projects have publicized usage statistics. A pilot project carried out in the Eda Kuhn Loeb Music Library of the Harvard College Library sought to determine whether library patrons actually understand and use QR codes. Results and analysis of the pilot project are provided, attempting to answer the question as to whether QR codes are worth the effort for libraries

The Aleut Kayak: How Aleut Technology Shaped History

If Russian and American imperialism in the north Pacific was the lever that turned the wheel of circumpolar history then the Aleut kayak, or “baidarka,” was the fulcrum. Without Aleut technology, and the labor of the Aleuts, the Russian-American Company would not have been able to derive tremendous profits from high value otter pelts. After the otters were nearly driven to extinction, the fur business transitioned to focusing on extracting a high volume of less valuable fur seal skins. Fur bearing animals were the most easily extractable form of wealth, and this wealth formed the basis for the United States justification of purchasing Alaska from Russia.[1] The role played by Aleut technology and labor appears to be insufficiently appreciated. Aleut technology and labor, and how they were exploited by Russia and the United States, will be the subject of this thesis. [1] James R. Gibson, Russian Dependence on the Natives of Alaska, An Alaska Anthology Interpreting the Past, ed. Stephen W Haycox and Mary Childers Mangusso (Seattle, University of Washington Press, 1996) http://muse.jhu.edu/ (accessed February 8, 2015), 21-42