Paul Cryan

Paul Cryan
United States Geological Survey | USGS · Fort Collins Science Center

PhD, MS

About

142
Publications
45,353
Reads
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6,905
Citations
Additional affiliations
May 1998 - present
United States Geological Survey
Position
  • Research Biologist
August 1996 - June 2003
University of New Mexico

Publications

Publications (142)
Article
Full-text available
Widespread bat fatalities at industrial wind turbines are a conservation issue with the potential to inhibit efficient use of an abundant source of energy. Bat fatalities can be reduced by altering turbine operations, but such curtailment decreases turbine efficiency. If additional ways of reducing bat fatalities at wind turbines were available suc...
Article
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Insectivorous bats are well known for their abilities to find and pursue flying insect prey at close range using echolocation, but they also rely heavily on vision. For example, at night bats use vision to orient across landscapes, avoid large obstacles, and locate roosts. Although lacking sharp visual acuity, the eyes of bats evolved to function a...
Article
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Determining the detailed movements of individual animals often requires them to carry tracking devices, but tracking broad-scale movement of small bats (<30 g) has been limited by transmitter technology and long-term attachment methods. This limitation inhibits our understanding of bat dispersal and migration , particularly in the context of emergi...
Article
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Long-distance migration evolved independently in bats and unique migration behaviors are likely, but because of their cryptic lifestyles, many details remain unknown. North American hoary bats (Lasiurus cinereus cinereus) roost in trees year-round and probably migrate farther than any other bats, yet we still lack basic information about their migr...
Article
1. Bats play crucial ecological roles and provide valuable ecosystem services, yet many populations face serious threats from various ecological disturbances. The North American Bat Monitoring Program (NABat) aims to use its technology infrastructure to assess status and trends of bat populations, while developing innovative and community‐driven co...
Article
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Background Bats of the genus Lasiurus occur throughout the Americas and have diversified into at least 20 species among three subgenera. The hoary bat ( Lasiurus cinereus ) is highly migratory and ranges farther across North America than any other wild mammal. Despite the ecological importance of this species as a major insect predator, and the par...
Article
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Wind energy producers need deployable devices for wind turbines that prevent bat fatalities. Based on the speculation that bats approach turbines after visually mistaking them for trees, we tested a potential light-based deterrence method. It is likely that the affected bats see ultraviolet (UV) light at low intensities. Here, we present the result...
Article
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Background Hoary bats ( Lasiurus cinereus ) are among the bat species most commonly killed by wind turbine strikes in the midwestern United States. The impact of this mortality on species census size is not understood, due in part to the difficulty of estimating population size for this highly migratory and elusive species. Genetic effective popula...
Article
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Bat fatalities at wind energy facilities in North America are predominantly comprised of migratory, tree‐dependent species, but it is unclear why these bats are at higher risk. Factors influencing bat susceptibility to wind turbines might be revealed by temporal patterns in their behaviors around these dynamic landscape structures. In northern temp...
Article
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The COVID-19 pandemic highlights the substantial public health, economic, and societal consequences of virus spillover from a wildlife reservoir. Widespread human transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) also presents a new set of challenges when considering viral spillover from people to naïve wildlife and other...
Article
Animals often migrate to exploit seasonally ephemeral food. Three species of nectar-feeding phyllostomid bats migrate north from Mexico into deserts of the United States (U.S.) each spring and summer to feed on blooms of columnar cacti and century plants (Agave spp.). However, the habitat needs of these important desert pollinators are poorly under...
Article
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Bats vocalize during flight as part of the sensory modality called echolocation, but very little is known about whether flying bats consistently call. Occasional vocal silence during flight when bats approach prey or conspecifics has been documented for relatively few species and situations. Bats flying alone in clutter-free airspace are not known...
Article
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Understanding natural behaviours is essential to determining how animals deal with new threats (e.g. emerging diseases). However, natural behaviours of animals with cryptic lifestyles, like hibernating bats, are often poorly characterized. White-nose syndrome (WNS) is an unprecedented disease threatening multiple species of hibernating bats, and pa...
Article
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Given rapid changes in agricultural practice, it is critical to understand how alterations in ecological, technological, and economic conditions over time and space impact ecosystem services in agroecosystems. Here, we present a benefit transfer approach to quantify cotton pest-control services provided by a generalist predator, the Mexican free-ta...
Article
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Solar power towers produce electrical energy from sunlight at an industrial scale. Little is known about the effects of this technology on flying animals and few methods exist for automatically detecting or observing wildlife at solar towers and other tall anthropogenic structures. Smoking objects are sometimes observed co-occurring with reflected,...
Data
List of all events in which birds were detected near solar towers. Bird detections in surveillance video imagery acquired during the spring and autumn site visits. Listed by sequential event number, date, time, whether clear evidence of burning in solar flux was observed (yes/no), descriptive comments on the event, and the types of surveillance cam...
Data
Total number of insects collected during each daytime and nighttime sampling period in May 2014. Also showing stations with greatest and second greatest number of insects captured in parentheses. Samples collected in the top portions of the two-part malaise trap are labeled as “T” for top, whereas samples collected from bottom portions are labeled...
Data
Total number of insects collected during each daytime and nighttime sampling period in September 2014. Also showing stations with greatest and second greatest number of insects captured in parentheses. Samples collected in the top portions of the two-part malaise trap are labeled as “T” for top, whereas samples collected from bottom portions are la...
Data
Example of radar tracking flying animals. Video of portable radar output on 16 May 2014 from 10:55:57 to 10:59:59 PDT. Range rings in green denote 250 m intervals out to 1500 m. The radar tracks flying animals as yellow dots (most recent location) with blue trails (previous locations). The radar is located in the center of the frames and is surroun...
Data
Timelapse of solar tower with frequent smoking objects. Time lapse video imagery from a wide-dynamic range (WDR) surveillance camera showing approximately 11 hours of a solar tower on 3 September 2014. The tower was operational from the start of the sequence until approximately noon, when it was taken offline. Small, visible and smoking objects tha...
Data
Bat flying at night imaged with near-infrared camera. Video sequences showing a bat flying past the receiver of a solar tower at night, approximately 100–140 m above ground level. First sequence shows imagery from near-infrared surveillance camera; the second shows same event imaged by thermal surveillance camera. (MP4)
Data
Dragonfly in solar flux. Video sequences showing simultaneous views from thermal surveillance camera (video inset to upper left) and wide-dynamic range (WDR) camera of a large dragonfly flying close to the receiver of a fluxing solar tower. Dragonfly can be seen as small white speck hovering in upper right corner of WDR scene just above corner of c...
Data
Insect burning in solar flux. SGT camera video in real elapsed time of insects flying in and around the Tower 1 flux field on 6 September 2014 at 08:45:25 PDT. One of these insects begins burning part way through the animation. The tower is just out of the field of view to the right. Temperature in °C is to the right. Dark regions in the upper-righ...
Data
Birds fly above solar flux and smaller smoking objects. Video imagery from WDR camera showing multiple objects (presumed to be small insects) smoking in the flux around the receiver of the solar tower while two large birds (Ravens) pass through the higher airspace above the tower and then circle above the flux to the northwest (left in video scene)...
Data
Examples of scenes imaged using surveillance cameras at solar towers. Still images showing various scenes and recording schemes imaged using thermal surveillance (TS) cameras (first four rows), wide dynamic range (WDR) surveillance cameras (5th through 14th rows; for scale, the red light imaged in the 14th row is approximately 12 cm in diameter and...
Data
Bird and bat imaged at close range with thermal surveillance camera. Still images of thermal surveillance video showing a large bird (top) and a bat (bottom) detected at night flying several meters above the camera. (PDF)
Data
Temperature of insect heating while flying in solar flux. Change in temperature over time of an insect entering the flux field at Tower 1 at 08:45:25 on 6 September 2014 as recorded on the SGT. Temperatures plateau at the camera’s saturation point of 59.6°C. This record corresponds with an animation presented as S9 Video. The last frame, and rightm...
Data
Specifications of video cameras used during study. Cameras listed by general type [including spectral range of sensor], model name, size of sensor array in pixels (px), and resolution (px/m), scene width and height, and minimum size of objects detected (i.e., necessary to fill a pixel), at two different distances relative to the bottom and top of t...
Data
Birds roost on solar tower while solar flux is present. Video sequences showing simultaneous views from thermal surveillance camera (video inset to lower right) and wide-dynamic range (WDR) camera of two pigeon-like birds approaching and roosting on the catwalk around the fluxing receiver of a solar tower for approximately 14 minutes before departi...
Data
Bird heating while flying through solar flux. Top: Six superimposed frames from the scientific-grade thermal imaging camera showing the track of a bird through the flux field on 5 September 2014. Temperature is indicated by color. Frame 5 from the left shows the bird with wings open and the camera saturated at 59.6°C. Bottom: Corresponding maximum...
Data
Timelapse of solar tower with few smoking objects. Time lapse video imagery from a wide-dynamic range (WDR) surveillance camera showing approximately 11.5 hours of a fluxing solar tower on 20 May 2014. Mostly clouds and steam released from the top of the tower are imaged and few small, smoking insects were observed on this day. (MP4)
Data
High-flying, large bird detected only with thermal surveillance camera. Video sequences showing what was presumed to be a large bird flying high above the solar tower and detected by the thermal surveillance camera (upper left video inset), but not by the WDR cameras (zoomed view shown to right). The thermal camera sometimes detected large birds th...
Data
Bird above solar tower with smoke or video ghosting. Video sequences showing a large bird circling in the airspace to the west (left in video scene) of a solar tower with visible trails in video imagery. It is unclear whether these trails were caused by video ‘ghosting’ or were attributable to smoke caused by solar flux. First sequence shows a far...
Data
Bird quickly flying past face of fluxing solar tower. Slow-motion video (one-quarter speed) of a large bird passing quickly near the south face of a fluxing solar tower receiver, passing within approximately 5 m and creating a shadow on the lit receiver. Smoking objects to the west (left) of the tower are smaller insects burning in the solar flux....
Data
Close-up of dragonfly near solar tower. Video sequences showing a dragonfly or other large 4-winged insect flying just above the upper catwalk of the solar tower. First sequence shows a close-up view imaged from a WDR camera mounted about half-way up the tower; the second sequence shows the same event from the same type of WDR camera positioned at...
Data
Small bird burning in solar flux. Video sequences showing simultaneous views from thermal surveillance camera (video inset to upper left) and wide-dynamic range camera of a bird flying close to the receiver of a fluxing solar tower. The bird appears to burn and then smokes within a few meters of the tower before exiting the scenes in the lower righ...
Data
Closeup timelapse of insects in solar flux. Time lapse of close-up video imagery from a wide-dynamic range surveillance camera with a telephoto lens (90 mm) showing approximately 1 hour of the airspace near a fluxing solar tower on 5 September 2014. For perspective, the red object in the lower left of the scene is a light that measures approximatel...
Data
Bats foraging near solar tower at night. Thermal surveillance video of bats flying (presumably foraging) near the upper parts of a solar tower at night. Catwalk around southwest corner of tower receiver is visible to right of scene. (MP4)
Article
Full-text available
Understanding of migration in small bats has been constrained by limitations of techniques that were labor-intensive, provided coarse levels of resolution, or were limited to population-level inferences. Knowledge of movements and behaviors of individual bats have been unknowable because of limitations in size of tracking devices and methods to att...
Article
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Despite conservation concerns for many species of bats, factors causing mortality in bats have not been reviewed since 1970. Here, we review and qualitatively describe trends in the occurrence and apparent causes of multiple mortality events (MMEs) in bats around the world. We compiled a database of MMEs, defined as cases in which ≥ 10 dead bats we...
Article
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White-nose syndrome is a fungal disease killing bats in eastern North America, but disease is not seen in European bats and is less severe in some North American species. We show that how bats use energy during hibernation and fungal growth rates under different environmental conditions can explain how some bats are able to survive winter with infe...
Article
Full-text available
Understanding seasonal distribution and movement patterns of animals that migrate long distances is an essential part of monitoring and conserving their populations. Compared to migratory birds and other more conspicuous migrants, we know very little about the movement patterns of many migratory bats. Hoary bats (Lasiurus cinereus), a cryptic, wide...
Article
Full-text available
Bat specimens held in natural history museum collections can provide insights into the distribution of species. However, there are several important sources of spatial error associated with natural history specimens that may influence the analysis and mapping of bat species distributions. We analyzed the importance of geographic referencing and err...
Technical Report
Full-text available
We studied the landscape distribution of endemic Hawaiian hoary bats (Lasiurus cinereus semotus) on the north Ko‘olau Mountains of O`ahu, Hawai`i, from May 2013 to May 2014, while simultaneously studying their behavior at wind turbines within the broader landscape. This research aimed to assess the risk that wind turbines pose to bats on the island...
Article
Full-text available
Background The physiological effects of white-nose syndrome (WNS) in hibernating bats and ultimate causes of mortality from infection with Pseudogymnoascus (formerly Geomyces) destructans are not fully understood. Increased frequency of arousal from torpor described among hibernating bats with late-stage WNS is thought to accelerate depletion of fa...
Article
Full-text available
Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012,...
Article
Full-text available
Conservation planning can be challenging due to the need to balance biological concerns about population viability with social concerns about the benefits biodiversity provide to society, often while operating under a limited budget. Methods and tools that help prioritize conservation actions are critical for the management of at-risk species. Here...
Article
Full-text available
Wind turbines are causing unprecedented numbers of bat fatalities. Many fatalities involve tree-roosting bats, but reasons for this higher susceptibility remain unknown. To better understand behaviors associated with risk, we monitored bats at three experimentally manipulated wind turbines in Indiana, United States, from July 29 to October 1, 2012,...
Article
Full-text available
Bats are sources of high viral diversity and high-profile zoonotic viruses worldwide. Although apparently not pathogenic in their reservoir hosts, some viruses from bats severely affect other mammals, including humans. Examples include severe acute respiratory syndrome coronaviruses, Ebola and Marburg viruses, and Nipah and Hendra viruses. Factors...