Morning flight behavior of nocturnally migrating birds along the western basin of Lake Erie

Many species of birds that normally migrate during the night have been observed engaging in so‐called morning flights during the early morning. The results of previous studies have supported the hypothesis that one function of morning flights is to compensate for wind drift that birds experienced during the night. Our objective was to further explore this hypothesis in a unique geographic context. We determined the orientation of morning flights along the southern shore of Lake Erie's western basin during the spring migrations of 2016 and 2017. This orientation was then compared to the observed orientation of nocturnal migration. Additionally, the orientation of the birds engaged in morning flights following nights with drifting winds was compared to that of birds following nights with non‐drifting winds. The morning flights of most birds at our observation site were oriented to the west‐northwest, following the southern coast of Lake Erie. Given that nocturnal migration was oriented generally east of north, the orientation of morning flight necessarily reflected compensation for accumulated, seasonal wind drift resulting from prevailingly westerly winds. However, the orientation of morning flights was similar following nights with drifting and non‐drifting winds, suggesting that birds on any given morning were not necessarily re‐orienting as an immediate response to drift that occurred the previous night. Given the topographical characteristics of our observation area, the west‐northwest movement of birds in our study is likely best explained as a more complex interaction that could include some combination of compensation for wind drift, a search for suitable stopover habitat, flying in a direction that minimizes any loss in progressing northward toward the migratory goal, and avoidance of a lake crossing.     

The sleep, subjective fatigue, and sustained attention of commercial airline pilots during an international pattern

International commercial airline pilots may experience heightened fatigue due to irregular sleep schedules, long duty days, night flying, and multiple time zone changes. Importantly, current commercial airline flight and duty time regulations are based on work/rest factors and not sleep/wake factors. Consequently, the primary aim of the current study was to investigate pilots' amount of sleep, subjective fatigue, and sustained attention before and after international flights. A secondary aim was to determine whether prior sleep and/or duty history predicted pilots' subjective fatigue and sustained attention during the international flights. Nineteen pilots (ten captains, nine first officers; mean age: 47.42+/-7.52 years) participated. Pilots wore wrist activity monitors and completed sleep and duty diaries during a return pattern from Australia to Europe via Asia. The pattern included four flights: Australia-Asia, Asia-Europe, Europe-Asia, and Asia-Australia. Before and after each flight, pilots completed a 5 min PalmPilot-based psychomotor vigilance task (PVT) and self-rated their level of fatigue using the Samn-Perelli Fatigue Checklist. Separate repeated-measures ANOVAs were used to determine the impact of stage of flight and flight sector on the pilots' sleep in the prior 24 h, self-rated fatigue, and PVT mean response speed. Linear mixed model regression analyses were conducted to examine the impact of sleep in the prior 24 h, prior wake, duty length, and flight sector on pilots' self-rated fatigue and sustained attention before and after the international flights. A significant main effect of stage of flight was found for sleep in the prior 24 h, self-rated fatigue, and mean response speed (all p < 0.05). In addition, a significant main effect of flight sector on self-rated fatigue was found (p < .01). The interaction between flight sector and stage of flight was significant for sleep in the prior 24 h and self-rated fatigue (both p < .05). Linear mixed model analyses indicated that sleep in the prior 24 h was a significant predictor of self-rated fatigue and mean response speed after the international flight sectors. Flight sector was also a significant predictor of self-rated fatigue. These findings highlight the importance of sleep and fatigue countermeasures during international patterns. Furthermore, in order to minimize the risk of fatigue, the sleep obtained by pilots should be taken into account in the development of flight and duty time regulations.     

The Sleep,Subjective Fatigue,and Sustained Attention of Commercial Airline Pilots during an International Pattern

International commercial airline pilots may experience heightened fatigue due to irregular sleep schedules, long duty days, night flying, and multiple time zone changes. Importantly, current commercial airline flight and duty time regulations are based on work/rest factors and not sleep/wake factors. Consequently, the primary aim of the current study was to investigate pilots' amount of sleep, subjective fatigue, and sustained attention before and after international flights. A secondary aim was to determine whether prior sleep and/or duty history predicted pilots' subjective fatigue and sustained attention during the international flights. Nineteen pilots (ten captains, nine first officers; mean age: 47.42±7.52 years) participated. Pilots wore wrist activity monitors and completed sleep and duty diaries during a return pattern from Australia to Europe via Asia. The pattern included four flights: Australia‐Asia, Asia‐Europe, Europe‐Asia, and Asia‐Australia. Before and after each flight, pilots completed a 5 min PalmPilot‐based psychomotor vigilance task (PVT) and self‐rated their level of fatigue using the Samn‐Perelli Fatigue Checklist. Separate repeated‐measures ANOVAs were used to determine the impact of stage of flight and flight sector on the pilots' sleep in the prior 24 h, self‐rated fatigue, and PVT mean response speed. Linear mixed model regression analyses were conducted to examine the impact of sleep in the prior 24 h, prior wake, duty length, and flight sector on pilots' self‐rated fatigue and sustained attention before and after the international flights. A significant main effect of stage of flight was found for sleep in the prior 24 h, self‐rated fatigue, and mean response speed (all p<0.05). In addition, a significant main effect of flight sector on self‐rated fatigue was found (p<.01). The interaction between flight sector and stage of flight was significant for sleep in the prior 24 h and self‐rated fatigue (both p<.05). Linear mixed model analyses indicated that sleep in the prior 24 h was a significant predictor of self‐rated fatigue and mean response speed after the international flight sectors. Flight sector was also a significant predictor of self‐rated fatigue. These findings highlight the importance of sleep and fatigue countermeasures during international patterns. Furthermore, in order to minimize the risk of fatigue, the sleep obtained by pilots should be taken into account in the development of flight and duty time regulations.     

Aircrew fatigue in trans-Atlantic morning and evening flights

The aim of the investigation was to compare sleepiness and sleep on westward morning and evening flights. Seven morning-crew pilots and seven evening-crew pilots participated. Data were collected before, during, and after outward-bound (westward) and homeward-bound (eastward) flights across six time zones. A sleep/wake diary (with repeated sleepiness and performance ratings) and wrist actigraphy were used for data collection. Maximum sleep was obtained after return and minimum sleep before the outward-bound flights. Actigraphy measures and sleep efficiency over the course of the study showed no significant differences between the morning and evening crews. There was a trend for a significant effect of morning vs. evening flight for time with heavy eyelids, with the homeward-bound flight showing more time with heavy eyelids. There were no significant differences between morning and evening crews with regard to napping during the flight. The duration of wakefulness was longer for the evening flight crew. There were significant interactions for Karolinska sleepiness scale (KSS) self-ratings on both the outward-bound and homeward-bound flights, and KSS was elevated during a considerable portion of the evening flights. Rated performance showed a significant time effect, but there was no difference in self-ratings between morning and evening crews. Evening flights involve higher levels of sleepiness than morning flights, presumably because of the close proximity in time to the circadian trough of alertness.     

Aircrew Fatigue in Trans‐Atlantic Morning and Evening Flights

The aim of the investigation was to compare sleepiness and sleep on westward morning and evening flights. Seven morning‐crew pilots and seven evening‐crew pilots participated. Data were collected before, during, and after outward‐bound (westward) and homeward‐bound (eastward) flights across six time zones. A sleep/wake diary (with repeated sleepiness and performance ratings) and wrist actigraphy were used for data collection. Maximum sleep was obtained after return and minimum sleep before the outward‐bound flights. Actigraphy measures and sleep efficiency over the course of the study showed no significant differences between the morning and evening crews. There was a trend for a significant effect of morning vs. evening flight for time with heavy eyelids, with the homeward‐bound flight showing more time with heavy eyelids. There were no significant differences between morning and evening crews with regard to napping during the flight. The duration of wakefulness was longer for the evening flight crew. There were significant interactions for Karolinska sleepiness scale (KSS) self‐ratings on both the outward‐bound and homeward‐bound flights, and KSS was elevated during a considerable portion of the evening flights. Rated performance showed a significant time effect, but there was no difference in self‐ratings between morning and evening crews. Evening flights involve higher levels of sleepiness than morning flights, presumably because of the close proximity in time to the circadian trough of alertness.     

The Shift-Work Accident Rate is More Related to the Shift Type than to Shift Rotation

The current study investigated the accident rates across morning, late, and night shifts in rotating shift-workers employed in two different shift rotations at the same steel work factory. A retrospective analysis has been performed of accident data (N = 578) over a 5-year period (2003 through 2007) of 730 male shift-workers employed in either a clockwise (mean age of the workers 38.1 ± SD 9.8 years) or counterclockwise rotation (mean age 38.0 ± SD 10.1 years) with comparable work conditions. The overall accident rate across the 24-h day was not significantly different between clockwise and counterclockwise shift rotation. In both shift-work rotations, morning shifts as opposed to night shifts exhibited a significantly higher accident rate. There was no significant difference between late shifts and morning or night shifts in either shift rotation. The increased accident rate in the morning shift at this steel factory could be related to the early starting time of the shift and to this shift being more labor intensive in both shift rotations. These findings suggest that work-related factors must be considered in addition to shift-work schedules when investigating accident rates in rotating shift-workers.     

Trapped in the darkness of the night: thermal and energetic constraints of daylight flight in bats

Bats are one of the most successful mammalian groups, even though their foraging activities are restricted to the hours of twilight and night-time. Some studies suggested that bats became nocturnal because of overheating when flying in daylight. This is because--in contrast to feathered wings of birds--dark and naked wing membranes of bats efficiently absorb short-wave solar radiation. We hypothesized that bats face elevated flight costs during daylight flights, since we expected them to alter wing-beat kinematics to reduce heat load by solar radiation. To test this assumption, we measured metabolic rate and body temperature during short flights in the tropical short-tailed fruit bat Carollia perspicillata at night and during the day. Core body temperature of flying bats differed by no more than 2°C between night and daytime flights, whereas mass-specific CO(2) production rates were higher by 15 per cent during daytime. We conclude that increased flight costs only render diurnal bat flights profitable when the relative energy gain during daytime is high and risk of predation is low. Ancestral bats possibly have evolved dark-skinned wing membranes to reduce nocturnal predation, but a low degree of reflectance of wing membranes made them also prone to overheating and elevated energy costs during daylight flights. In consequence, bats may have become trapped in the darkness of the night once dark-skinned wing membranes had evolved.     

Impact of layover length on sleep, subjective fatigue levels, and sustained attention of long-haul airline pilots

Long-haul airline pilots often experience elevated levels of fatigue due to extended work hours and circadian misalignment of sleep and wake periods. During long-haul trips, pilots are typically given 1-3 d off between flights (i.e., layover) to recover from, and prepare for, duty. Anecdotally, some pilots prefer long layovers because it maximizes the time available for recovery and preparation, but others prefer short layovers because it minimizes both the length of the trip, and the degree to which the body clock changes from "home time" to the layover time zone. The aim of this study was to examine the impact of layover length on the sleep, subjective fatigue levels, and capacity to sustain attention of long-haul pilots. Participants were 19 male pilots (10 Captains, 9 First Officers) working for an international airline. Data were collected during an 11- or 12-d international trip. The trips involved (i) 4 d at home prior to the trip; (ii) an eastward flight of 13.5 h across seven time zones; (iii) a layover of either 39 h (i.e., short, n = 9) or 62 h (i.e., long, n = 10); (iv) a return westward flight of 14.3 h across seven time zones; and (v) 4 d off at home after the trip. Sleep was recorded using a self-report sleep diary and wrist activity monitor; subjective fatigue level was measured using the Samn-Perelli Fatigue Checklist; and sustained attention was assessed using the psychomotor vigilance task for a personal digital assistant (PalmPVT). Mixed-model regression analyses were used to determine the effects of layover length (short, long) on the amount of sleep that pilots obtained during the trip, and on the pilots' subjective fatigue levels and capacity to sustain attention. There was no main effect of layover length on ground-based sleep or in-flight sleep, but pilots who had a short layover at the midpoint of their trip had higher subjective fatigue levels and poorer sustained attention than pilots who had a long layover. The results of this study indicate that a short layover during a long-haul trip does not substantially disrupt pilots' sleep, but it may result in elevated levels of fatigue during and after the trip. If short layovers are used, pilots should have a minimum of 4 d off to recover prior to their next long-haul trip.     

Effects of delayed mating on preimplantation embryos in spontaneously ovulated mice

The effects of delayed mating on mouse preimplantation embryos (78 ± 1 hours) were studied by setting up different mating periods in relation to the estimated time of spontaneous ovulation. Copulation occurred even in the late morning and early afternoon after the night of spontaneous ovulation. However, females mated in the early afternoon had no viable embryos at the time of laparotomy. Although embryonic development was not affected in the groups mated 6 or 10 hours after estimated ovulation, the percentage of degenerated embryos was increased in these groups. These results suggest that prolonged intervals between the estimated time of ovulation and mating have some deleterious effects on preimplantation embryos.     

Sleep/Wake Cycle Parameters and Sleep/Fatigue Complaints in Female Night Workers

Adaptation to shift-work is influenced by the way workers schedule their lives, including allocation of sleep episodes. Female workers (n = 29) engaged at an assembly line were studied as to individual differences in sleep parameters in order to verify whether those differences could be related to the manifestation of sleep and fatigue complaints. The sample was composed of women (20–40 y) working at night from Monday to Friday. Sleep data were based on daily sleep logs which were filled out by the workers for 10 consecutive weeks. In the analyses of sleep data both diurnal episodes between consecutive night shifts and noctural sleep episodes preceding working nights were taken into account. Worker's complaints were analyzed through questions extracted from an interview form encompassing questions on fatigue associated with the work schedule and on dissatisfaction with sleep on weekdays and weekends. The analysis of diurnal episodes showed no significant correlation between the total amount of sleep per day and the total number of complaints. Nevertheless, the latter was correlated to the length of the first sleep episode on a day, which usually began in the morning. As to sleep onset times, significant correlations were not detected concerning the first diurnal episodes. The analysis of nocturnal episodes did not reveal any significant correlation between sleep parameters and complaints. Results indicate that workers whose sleep onsets were allocated to the morning and were able to sleep for many consecutive hours, tended to show less complaints, suggesting that the temporal allocation of diurnal sleep and its length are relevant in the determination of how these workers perceive fatigue and sleep quality.     

Occupational stress and work efficiency of nursing staff engaged in rotating shift work

Occupational stress and stress-related performance impairment is a common feature among hospital nurses engaged in rotating shift work, particularly night work. This cross-sectional survey determined workplace stress and cognitive efficiency of nursing staff engaged in rotating shift work. One hundred twenty-two full-time staff nurses in three different government hospitals in West Bengal, India, were the participants. Perceived exertion, alertness, sleep duration and various performance tests were performed. Sleep duration was least between repeated night shifts in comparison with the other shifts. Though alertness and performance of the staff nurses varied on different shifts, the late portion of the night shift as well as the early portion of the morning shift was most prone to impairment of work efficiency.     

Sleep/Wake Cycle Parameters and Sleep/Fatigue Complaints in Female Night Workers

Adaptation to shift-work is influenced by the way workers schedule their lives, including allocation of sleep episodes. Female workers ( n = 29) engaged at an assembly line were studied as to individual differences in sleep parameters in order to verify whether those differences could be related to the manifestation of sleep and fatigue complaints. The sample was composed of women (20-40 y) working at night from Monday to Friday. Sleep data were based on daily sleep logs which were filled out by the workers for 10 consecutive weeks. In the analyses of sleep data both diurnal episodes between consecutive night shifts and noctural sleep episodes preceding working nights were taken into account. Worker's complaints were analyzed through questions extracted from an interview form encompassing questions on fatigue associated with the work schedule and on dissatisfaction with sleep on weekdays and weekends. The analysis of diurnal episodes showed no significant correlation between the total amount of sleep per day and the total number of complaints. Nevertheless, the latter was correlated to the length of the first sleep episode on a day, which usually began in the morning. As to sleep onset times, significant correlations were not detected concerning the first diurnal episodes. The analysis of nocturnal episodes did not reveal any significant correlation between sleep parameters and complaints. Results indicate that workers whose sleep onsets were allocated to the morning and were able to sleep for many consecutive hours, tended to show less complaints, suggesting that the temporal allocation of diurnal sleep and its length are relevant in the determination of how these workers perceive fatigue and sleep quality.     

Heart rate variability during long truck driving work

We recorded ambulatory electrocardiograms of 6 long distance truck drivers during their work period in order to observe the affect of autonomic nervous function and symptoms while doing their work. We also recorded their work patterns every minute. The RR50 value and the LFP/HFP ratio were calculated every two minutes based on R-R interval data. RR50 was significantly higher during taking naps than during other periods of work shifts, while, the LFP/HFP ratio showed significantly lower during taking naps than during other periods of work shifts. RR50 in the morning was significantly higher than that in the afternoon. On the contrary, the LFP/HFP ratio showed opposite tendency. Only on the times of driving, RR50 was significantly higher in the morning than that in the afternoon. On the other hand, the LFP/HFP ratio showed an opposite tendency. These results show that the parasympathetic nervous activities were more dominant than sympathetic nervous activities in the morning during the subjects were doing long distance truck driving including midnight work. Driving while in high parasympathetic nervous activity levels may add to cardiovascular stress and lead to drowsiness. And this may result in disrupted attention. It is necessary to decrease work time and improve working conditions of truck drivers working long-hour shifts.     

The Use of Actimetry to Assess Changes to the Rest–Activity Cycle

The endogenous circadian oscillator (the body clock) is slow to adjust to altered rest–activity patterns. As a result, several negative consequences arise during night work and after time‐zone transitions. The process of adjustment can be assessed by measurements of the sleep electroencephalogram (EEG), core temperature or melatonin secretion, for example, but these techniques are very difficult to apply in field studies, and make very great demands upon both experimenters and subjects. We have sought to establish if the activity record, measured conveniently and unobtrusively by a monitor attached to the wrist, can be treated in ways that enable estimates to be made of the disruption caused by changes to the rest–activity cycle, and the process of adjustment to them. In Part A, we describe the calculation and assessment of a series of “activity indices” that measure the overall activity pattern, activity when out of bed or in bed, or the activity in the hours adjacent to going to bed or getting up. The value of the indices was assessed by measuring changes to them in subjects undergoing night work or undergoing time‐zone transitions. In both cases, there is a large body of literature describing the changes that would be expected. First, night workers (working 2 to 4 successive night shifts) were investigated during rest days and night shifts. The indices indicated that night work was associated with lower activity when the subjects were out of bed and higher activity when in bed. Some indices also measured when subjects took an afternoon nap before starting a series of night shifts and gave information about the process of adjustment to night work and recovery from it. Second, in studies from travelers crossing six or more time zones to the east or west, the indices indicated that there were changes to the rest–activity cycle immediately after the flights, both in its overall profile and when activity of the subjects in bed or out of bed was considered, and that adjustment took place on subsequent days. By focusing on those indices describing the activity records during the last hour in bed (LHIB) and the first hour out of bed (FHOB), some evidence was found for incomplete adjustment of the body clock, and for differences between westward and eastward flights. In Part B, the battery of indices are applied to the activity records of long‐haul pilots, whose activity patterns showed a mixture of effects due to night work and time‐zone transitions. Actimetry was performed during the flights themselves and during the layover days (which were either rest or work days). The indices indicated that all pilots had disrupted rest–activity cycles caused by night flights, and that there were added problems for those who had also undergone time‐zone transitions. Rest days were valuable for normalizing the activity profile. For those pilots who flew to the west, adjustment was by delay, though not all aspects of the rest–activity cycle adjusted immediately; for those who flew to the east, some attempted to advance their rest–activity cycle while others maintained home‐based activity profiles. The indices indicated that the activity profile was disrupted more in those pilots who attempted to advance their rest–activity cycle. We conclude that objective estimates of the disruption caused to the rest–activity cycle and the circadian system can be obtained by suitable analysis of the activity record.     

Delayed sleep phase disorder and Attention deficit and hyperactivity symptoms in a teenager

JR is an 18-year-old male with five-year history of going to bed late and waking up late. He gives history of poor frustration tolerance, inattention and fidgetiness in school for which he has been unsuccessfully been treated with stimulant medications for last 3 years. There is history of similar sleep problems in his father who works nights as a mechanic. JR's sleep log shows him going to bed early morning and waking up late morning/afternoon. He shows no sleep maintenance problems and sleeps an average of 8 h per night. He shows no symptoms of depression, anxiety, inattention or hyperactivity during his hospital stay. He does not show any learning, cognitive, attention or intellectual deficits. He is currently not taking any medications. He is discharged home after 3-day hospital stay and is reportedly doing well working in a video rental store at night.     

Effect of environmental factors on the flight activity of Trialeurodes vaporariorum (Westwood) under greenhouse conditions

The flight activity of the greenhouse whitefly Trialeurodes vaporariorum (Westwood) was monitored over a 3‐year period in greenhouses containing tomato and zucchini crops. The environmental factors affecting its flight activity and dispersal were analyzed. Among the climatic variables, temperature had a positive impact on T. vaporariorum flight, whereas relative humidity had only a weak effect. More flights were made during the morning and afternoon, with fewer flights occurring when the temperature was above 25°C in greenhouses containing zucchini or above 30°C in those containing tomato; no flights were recorded when the temperature was 12.30°C in either setting. Flight typology, classified as short, long or dispersal, and covering a few centimeters to more than 2–3 m, was influenced by the vegetative condition of the plants. As the plants aged and declined in condition, the number of short flights decreased, whereas the number of long and dispersal flights increased. Based on these results, we can conclude that the dispersal of T. vaporariorum in greenhouses containing either tomato or zucchini crops is generally influenced by environmental factors, which also affect the type of flight, with a trade‐off between short and long dispersal flights. However, adult dispersal is driven not only by temperature, but also by other factors, such as conspecific density and time of the day. Therefore, producers must consider such factors when aiming to reduce the dispersal of pest insects within greenhouses and, thus, to maintain the productivity of their crops.     

Dating pregnancy times in rats and the effect of ovum supermaturation on the quantity of live embryos]

The fecundity of white rats was compared for the night and morning matings (late and early). The mating of animals at the stage of oestrus for 1.5 hrs early in the morning is the optimum one for obtaining females with the precisely dated time of pregnancy. The progeny of females fertilized after 10-11 hours in the morning, i. e. 9-11 hrs after the ovulation, decreases almost twice at the expense of embryonic mortality both prior and after the implantation due to the low viability of "overmatured" eggs.     

Energy Expenditure and Metabolic Changes of Free-Flying Migrating Northern Bald Ibis

Many migrating birds undertake extraordinary long flights. How birds are able to perform such endurance flights of over 100-hour durations is still poorly understood. We examined energy expenditure and physiological changes in Northern Bald Ibis Geronticus eremite during natural flights using birds trained to follow an ultra-light aircraft. Because these birds were tame, with foster parents, we were able to bleed them immediately prior to and after each flight. Flight duration was experimentally designed ranging between one and almost four hours continuous flights. Energy expenditure during flight was estimated using doubly-labelled-water while physiological properties were assessed through blood chemistry including plasma metabolites, enzymes, electrolytes, blood gases, and reactive oxygen compounds. Instantaneous energy expenditure decreased with flight duration, and the birds appeared to balance aerobic and anaerobic metabolism, using fat, carbohydrate and protein as fuel. This made flight both economic and tolerable. The observed effects resemble classical exercise adaptations that can limit duration of exercise while reducing energetic output. There were also in-flight benefits that enable power output variation from cruising to manoeuvring. These adaptations share characteristics with physiological processes that have facilitated other athletic feats in nature and might enable the extraordinary long flights of migratory birds as well.     

Arrivals of Hitchhiking Insect Pests on International Cargo Aircraft at Miami International Airport

In a study of hitchhiking or contaminating insect pests on international cargo aircraft at Miami International Airport from 1998 to 1999, it was found that contamination rates were greatest, 23%, on cargo flights from Central America and much lower, near 5%, on flights from all other regions. We reanalyzed the study data to test for associations between contaminated flights and factors such as season, cargo type, and time of departure (night or day), and developed probabilistic models for predicting insect pest arrivals by region and pest risk levels. Significant (P < 0.05) associations were detected between contaminated flights and (1) wet season flights from Central America, (2) flights carrying plant products and clothing or fabrics, and (3) flights departing at night from the country of origin. In Monte Carlo simulations, numbers of arriving mated insect pests were greatest for cargo flights from Central America, because of great contamination rates, and South America, because of the large volume of flights from there. Few insects arrived on flights from the Caribbean, and few high-risk insects arrived from anywhere. Although the likelihood of establishment in South Florida via this pathway could not be estimated, based upon arrivals the greatest threats were posed by moderate-risk insect pests on flights from Central and South America. Simulations indicated that switching to daytime departures only reduced pest arrivals by one-third. The simplest mechanism for pathway entry that explains the associations found is that insects entered aircraft randomly but sometimes remained because of the presence of certain cargo types. Hence, contamination rates were greater during the wet season because of greater abundance locally, and on nighttime flights because of greater abundance around lighted loading operations. Empty planes probably had no pests because pests had no access to holds. Thus, the best mitigation strategies for this pathway will likely be those that exclude insects from holds or reduce the attractiveness of night loading operations. Optimizing inspections based on associations is also possible but will be less effective for regions such as South America, with high flight volumes and low contamination rates. Comparisons to other pathways indicates the potential importance of hitchhikers on cargo aircraft at MIA.     

Drivers affecting habitat use in Afrotropical hipposiderid and pteropodid bats

Assessing how bats respond to habitat attributes requires an integrative approach to reliably predict direct community-level effects. We focused on hipposiderid and pteropodid bats because of their diverse resource use patterns, body size ranges, and dispersal abilities. We combined an array of bat species-level characteristics with key forest stand characteristics that may covary with habitat use. Twelve stations were sampled in the Lomami and Yangambi landscapes, Democratic Republic of the Congo. We investigated whether species-level flight ability of bats and forest stand characteristics can affect bat commuting flights and community-level estimates of both species detection and habitat occupancy. We captured bats for 108 trap-nights. Three sampling events (early evening, middle of the night, and early morning) were replicated for each survey night. Hipposiderids showed an early evening flight peak, while flight activity of pteropodids was constant throughout the night, but increased around the middle of the night. Species capture probability decreased with higher wing loading in hipposiderids and was negatively correlated with higher wing aspect ratio in pteropodids. Forest occupancy of hipposiderids increased along the gradient towards waterways, while pteropodid occurrence was not directly linked to measured forest stand variables. This suggests a consequence of habitat patterns at larger spatial scales, which would need clarifying through additional data collection. We discuss these findings in terms of resource-use strategies of clutter-tolerant and clutter-intolerant species. We argue that the occurrence of specific bat species and their habitat use patterns can serve as surrogate measures of ecosystem health.