Long Live the King? A GIS Analysis of Climate Change’s Impact on the Future Wintering Range and Economy of the Monarch Butterfly (Danaus plexippus) in Mexico

The annual migration of the monarch butterfly (Danaus plexippus) is a natural phenomenon widely integrated into the popular and social imagination of North America. However, this migratory population has recently declined. I investigated the threat of climate change on the future distribution of suitable monarch habitat, using ArcGIS to create a model of current and future monarch habitat. I also analyzed municipal data for 5 communities in Mexico State in an examination of the social aspects of the Monarch Butterfly Biosphere Reserve [MBBR]. According to my model, an estimated 38.6% to 69.8% of current monarch habitat may be lost within the MBBR by 2050, potentially affecting 14 of the 19 current colonies, while throughout the Trans-Mexican Volcanic Belt, 52% to 76% of suitable habitat could disappear. Most members of these 5 communities work in the agriculture and service sectors, and all but one reported a tourist infrastructure. The potentially large losses in suitable habitat question the effectiveness of protected areas in the face of climate change, and suggest the need to develop a more resilient strategy to protect both natural and social aspects of the monarch migration

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