The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Peter H. Becker - One of the best experts on this subject based on the ideXlab platform.
-
In search of the gap: temporal and spatial dynamics of settling in natal Common Tern recruits
Behavioral Ecology and Sociobiology, 2015Co-Authors: Peter H. BeckerAbstract:In colonial birds, criteria used for the first choice of a nest site and its temporal and spatial dynamics are rarely studied. This paper addresses first settlement of natal recruits in Common Terns STerna hirundo at a stable colony site subdivided into six islands of equal size and habitat. Using extensive individual-based data of aged and sexed individuals with known recruitment age, I focus on timing of laying, island selection in relation to density and centrality, and movements after first breeding. Recruits’ laying date was timed between that of experienced and replacement breeders. The proportion of early clutches, density, and age of breeders were higher at the islands’ edge (the preferred area), whereas late clutches predominated at the center. Sixty-eight percent of recruits settled at the center and only 32 % at the islands’ edge. With advancing age, breeders shifted nest sites from the island center towards the edge. In 7 out of 18 years, annual recruit numbers were not evenly distributed among the islands. Density did not affect island selection, but in years with low numbers of recruits, their aggregation was more distinct. Recruits’ preference of a specific island rarely lasted more than 2 years. Depletion of the central area in the year after recruitment initially attracted new recruits before succeeding cohorts switched to another island. The dynamics of recruits’ settlement indicate diverging tendencies of attracting or repelling recruits at a specific subcolony, affected by group adherence and cohort size, density, and advancing laying date with age and shifts of nest sites towards the preferred subcolony periphery.
-
fitness prospects effects of age sex and recruitment age on reproductive value in a long lived seabird
Journal of Animal Ecology, 2015Co-Authors: He Zhang, Peter H. Becker, Maren Rebke, Sandra BouwhuisAbstract:Reproductive value is an integrated measure of survival and reproduction fundamental to understanding life-history evolution and population dynamics, but little is known about intraspecific variation in reproductive value and factors explaining such variation, if any. By applying generalized additive mixed models to longitudinal individual-based data of the Common Tern STerna hirundo, we estimated age-specific annual survival probability, breeding probability and reproductive performance, based on which we calculated age-specific reproductive values. We investigated effects of sex and recruitment age (RA) on each trait. We found age effects on all traits, with survival and breeding probability declining with age, while reproductive performance first improved with age before levelling off. We only found a very small, marginally significant, sex effect on survival probability, but evidence for decreasing age-specific breeding probability and reproductive performance with RA. As a result, males had slightly lower age-specific reproductive values than females, while birds of both sexes that recruited at the earliest ages of 2 and 3 years (i.e. 54% of the Tern population) had somewhat higher fitness prospects than birds recruiting at later ages. While the RA effects on breeding probability and reproductive performance were statistically significant, these effects were not large enough to translate to significant effects on reproductive value. Age-specific reproductive values provided evidence for senescence, which came with fitness costs in a range of 17-21% for the sex-RA groups. Our study suggests that intraspecific variation in reproductive value may exist, but that, in the Common Tern, the differences are small.
-
Predicting reproductive success from hormone concentrations in the Common Tern (STerna hirundo) while considering food abundance.
Oecologia, 2014Co-Authors: Juliane Riechert, Peter H. Becker, Olivier ChastelAbstract:In birds, reproductive success is mainly a function of skill or environmental conditions, but it can also be linked to hormone concentrations due to their effect on behavior and individual decisions made during reproduction. For example, a high prolactin concentration is required to express parental behaviors such as incubation or guarding and feeding the young. Corticosterone level, on the other hand, is related to energy allocation or stress and foraging or provisioning effort. In this study, we measured individual baseline prolactin and corticosterone between 2006 and 2012 in breeding Common Terns (STerna hirundo) using blood-sucking bugs. Reproductive parameters as well as prey abundance on a local and a wider scale were also determined during this period. Baseline prolactin and corticosterone varied significantly between years, as did breeding success. At the individual level, prolactin was positively and corticosterone was negatively linked to herring and sprat abundance. At the population level, we also found a negative link between corticosterone and prey abundance, probably reflecting overall foraging conditions. High prolactin during incubation was mainly predictive of increased hatching success, potentially by supporting more constant incubation and nest-guarding behavior. It was also positively linked to a lesser extent with fledging success, which could indicate a high feeding rate of young. Corticosterone concentration was positively related to high breeding success, which may be due to increased foraging activity and feeding of young. In general, our study shows that baseline prolactin and corticosterone levels during incubation can predict reproductive success, despite the presence of an interval between sampling and hatching or fledging of young.
-
Colony size and not nest density drives reproductive output in the Common Tern STerna hirundo
Ibis, 2013Co-Authors: K. Lesley Szostek, Peter H. Becker, Barbara C. Meyer, Stefan R. Sudmann, Heribert ZintlAbstract:Density is known to be an important factor in population size regulation. Several mechanisms of density limitation have been identified in colonial birds. We studied competition in Common Terns STerna hirundo to assess whether the factor limiting reproductive output was competition for nest-sites, which is dependent on local nest density, or density-dependent competition for food resources, which is dependent on overall colony size using the same foraging area. We found strong associations of both colony size and nest density with reproductive output in five colonies of Common Terns in three different habitats (one marine, two freshwater). Based on detailed long-term datasets of six separate sub-colonies of the Banter See colony that differed in nest density, we found that reproductive success was not related to nest density but to overall colony size, possibly a result of resource depletion and food competition. We also found carry-over effects of colony size during rearing on post-fledging return rate. These results have important implications for the conservation management plans aimed at recovering declining populations of Common Terns.
-
Is the additional effort of renesting linked to a hormonal change in the Common Tern?
Journal of Comparative Physiology B, 2013Co-Authors: Juliane Riechert, Olivier Chastel, Peter H. BeckerAbstract:The production of and care for a replacement clutch can bear costs in terms of future reproduction or survival. However, renesting is quite Common among seabirds and can contribute considerably to individual fitness. Prolactin and corticosterone are two hormones involved in the mediation of breeding behavior and, as they are linked to body condition or effort, it is of interest if these hormone values change during a second demanding breeding phase within a year. We compared baseline prolactin and corticosterone between the first and the renesting attempt in Common Terns (STerna hirundo) on individual level. Therefore, in addition to control birds, 37 breeders were sampled during incubation of their first and their replacement clutch in 2008 and 2009. Blood samples were taken non-invasively by blood-sucking bugs. Prolactin level was lower during the renesting period, especially in birds which abandoned their clutch afterwards, whereas corticosterone did not change. Excluding the deserting birds, the reduced prolactin level was not linked to minor success, but could be related to seasonal processes. The control group of late laying Common Terns showed comparably low prolactin values, but increased corticosterone concentrations. Renesting individuals exhibited higher prolactin during incubation of their first clutch than non-renesting birds, probably indicating their higher quality. The fact that Terns still have relatively high prolactin and low corticosterone values during renesting might confirm their higher quality and suggests that they are able to meet the costs of a second demanding breeding period without being considerably stressed.
David M. Bird - One of the best experts on this subject based on the ideXlab platform.
-
RESEARCH ARTICLE Population Census of a Large Common Tern Colony with a Small Unmanned Aircraft
2016Co-Authors: Dominique Chabot, Shawn R. Craik, David M. BirdAbstract:Small unmanned aircraft systems (UAS) may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests) coastal Common Tern (STerna hirundo) colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic Tern counts to ground nest counts in 45 plots (5-m radius) throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the fol-lowing day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972–0.989, P< 0.001) and regression coefficients ranged from 0.928–0.977 Terns/nest. Full colony aerial counts were 93.6 % and 94.0%, respectively, of the ground count. Varying visibility of Terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common Tern colonies following our method should yield population estimates in the 93–96 % range of ground counts. Although the Terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird research-ers and managers to consider taking advantage of this burgeoning technology
-
population census of a large Common Tern colony with a small unmanned aircraft
PLOS ONE, 2015Co-Authors: Dominique Chabot, Shawn R. Craik, David M. BirdAbstract:Small unmanned aircraft systems (UAS) may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests) coastal Common Tern (STerna hirundo) colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic Tern counts to ground nest counts in 45 plots (5-m radius) throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the following day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972–0.989, P < 0.001) and regression coefficients ranged from 0.928–0.977 Terns/nest. Full colony aerial counts were 93.6% and 94.0%, respectively, of the ground count. Varying visibility of Terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common Tern colonies following our method should yield population estimates in the 93–96% range of ground counts. Although the Terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird researchers and managers to consider taking advantage of this burgeoning technology.
-
Population census of a large Common Tern colony with a small unmanned aircraft
2015Co-Authors: Dominique Chabot, Shawn R. Craik, David M. BirdAbstract:Abstract: Small unmanned aircraft systems (UAS) may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests) coastal Common Tern (STerna hirundo) colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic Tern counts to ground nest counts in 45 plots (5-m radius) throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the following day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972-0.989, P < 0.001) and regression coefficients ranged from 0.928-0.977 Terns/nest. Full colony aerial counts were 93.6% and 94.0%, respectively, of the ground count. Varying visibility of Terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common Tern colonies following our method should yield population estimates in the 93-96% range of ground counts. Although the Terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird researchers and managers to consider taking advantage of this burgeoning technology. About the data: Raw aerial photos were captured in JPEG format by a Canon Powershot S90 10-megapixel camera mounted on an Aerial Insight AI-Multi electric fixed-wing UAS. The highest quality overlapping photos of each of the two islands comprising the Tern colony were then mosaicked using the PTGui panoramic stitching software. Photomosaics were then imported into ArcGIS and georeferenced with ground control points collected with a Trimble Pathfinder GPS at a series of yellow or orange plastic cones (visible in the imagery) marking the centre of plots in which ground nest counts were compared to aerial Tern counts. Overall disturbance levels on each of the two islands were scored on a scale of 0–2 from a distance by an observer at 30-second intervals throughout UAS flights as well as "matched" control periods starting 10 minutes following landing. For more information about this research or the data, please contact: dominique.chabot@mail.mcgill.ca
Keith C. Hamer - One of the best experts on this subject based on the ideXlab platform.
-
2001 Common and Arctic Tern nest sites 49 A COMPARISON OF ARCTIC Tern STERA PARADISAEA AND Common Tern S. HIRUDO NEST-SITE CHARACTERISTICS ON COQUET
2015Co-Authors: Island North-east England, James A. Robinson, Lorraine S. Chivers, Keith C. HamerAbstract:paradisaea and Common Tern S. hirundo nest-site characteristics on Coquet Island, north-east England. Atlantic Seabirds 3(2): 49-58. The nest-site characteristics of Common Terns STerna hirundo and Arctic Terns S. paradisaea were examined at a mixed colony at Coquet Island, north-east England. All Common Terns and the majority of Arctic Terns nested within areas of short grass enclosed by swards of much taller and dense vegetation. The majority of these nesting areas had been artificially managed to attract nesting Terns. A fifth of all Arctic Tern pairs nested on sandy and shingle beaches. Within vegetated nesting areas, Arctic Terns nested less densely, in larger open areas and in shorter vegetation than did Common Terns. either species showed preferences for the types of plants amongst which to nest
-
Offspring sex ratio in the Common Tern STerna hirundo, a species with negligible sexual size dimorphism
Ibis, 2004Co-Authors: Kathy L. Fletcher, Keith C. HamerAbstract:In many vertebrates, male offspring are affected more than female offspring by adverse conditions during growth, resulting in facultative adjustment of offspring sex ratio by parents in response to social and environmental conditions during breeding. The greater vulnerability of male offspring is generally attributed to their higher energy requirements associated with their larger size, although greater sensitivity to adverse conditions could be related to other factors such as negative effects of androgens on male physiology. To control for sexual differences in body size, we examined variation in offspring sex ratio in the Common Tern STerna hirundo, a species with negligible sexual size dimorphism. In this species, the last-laid egg (termed the c-egg) is smaller than the first two and hatches last, so that the chick obtains relatively little food and hence has a low probability of survival to fledging. This species thus provides a powerful model for examining sex-linked mortality and sex ratio variation under natural conditions. We found that the sex ratio of c-eggs, but not of earlier laid eggs, was significantly biased in favour of females. Chicks hatched from c-eggs (termed c-chicks) had low survival but female c-chicks had significantly higher survival than male c-chicks. These data provide strong evidence that factors other than sexual size dimorphism are responsible for producing greater vulnerability of male offspring to adverse conditions during growth.
Brian G. Palestis - One of the best experts on this subject based on the ideXlab platform.
-
Movements of Common Tern (STerna hirundo) Chicks from the Nest with Age
Waterbirds, 2019Co-Authors: Monica M. Valero, Brian G. PalestisAbstract:Common Tern (STerna hirundo) chicks are highly mobile, as they are semi-precocial. However, they generally stay in the territories near their nests until soon after fledging. In the salt marsh-breeding population in Barnegat Bay, New Jersey, USA, Common Tern chicks were recorded far from their nests before fledging. Movements from the nest were quantified at two islands in Barnegat Bay. For the first 1-3 days, chicks stayed very close to the nest. By 4 to 6 days of age, no chicks were within the nest cup, but they typically remained nearby, at a median distance of 0.45 m from the nest. From 1 to 3 weeks of age, median distance from the nest steadily increased from about 1 to 4 m. Among those chicks older than 3 weeks, the median distance away from the nest was 6.45 m, and none were found closer than 1.75 m. Common Tern chicks older than one week were usually not present in their territories, despite continuing to rely on their parents for care. The contrast between this and previous studies of the Common Tern may relate to habitat differences.
-
responses of Common Tern chicks to feather sample removal
The Wilson Journal of Ornithology, 2013Co-Authors: Brian G. Palestis, Michael D StantonAbstract:Abstract Feather sampling is often assumed to be harmless, but this assumption has not been tested. From 2008–2012, we recorded the behavior of 340 Common Tern (STerna hirundo) chicks following the removal of a pinch of body feathers. Only 11.2% of these chicks ran after sampling and 69.4% showed no visible reaction to sampling. The probability of a chick running away increased with age. We therefore recommend that sampling be conducted as soon as possible after juvenal feathers emerge. There was evidence for individual differences in behavior: approximately 71% of chicks that ran after feather sampling also ran away when re-encountered on later dates, while other chicks rarely did so. We found no evidence that removal of feather samples increased chick mortality, supporting the assumption that this technique is minimally invasive, but small differences in mortality rates would have been difficult to detect.
-
carriage of bacteria and protozoa in the intestinal tract of Common Tern chicks
Waterbirds, 2012Co-Authors: William A Rivera, Brian G. Palestis, Jusuf S Husic, Corey E Gaylets, Roy H Mosher, Adam J HoulihanAbstract:Little is known about the intestinal microflora of Common Terns (STerna hirundo) and their capacity to disseminate human gastrointestinal pathogens along migratory flyways. Common Tern chicks on Pettit Island in Barnegat Bay, New Jersey, USA, were evaluated for carriage of bacterial and protozoan pathogens. Oropharyngeal and cloacal swabs were taken for culture-based detection of bacterial gastrointestinal pathogens during the 2009 and 2010 breeding seasons. Bulk fecal samples were also taken during the 2010 nesting season to determine Cryptosporidium oocyst loads. Of 125 birds sampled in 2009, none carried Salmonella and only one carried Campylobacter. Moreover, the majority of birds sampled in the 2009 breeding season carried Escherichia coli and Klebsiella ozaenae, members of bacterial family Enterobacteriaceae. In 2010, one of the 54 birds sampled carried Salmonella and none had Campylobacter in their intestines. Similar to the birds sampled in 2009, the 2010 cohort showed relatively high carriage of E. coli and K. ozaenae. Microscopic examination of fecal smears obtained in 2010 revealed that 39 of 54 Common Tern chicks had microscopic structures consistent with Cryptosporidium oocysts in their intestines. These data indicate that Common Tern chicks in Barnegat Bay present low to no threat to public health through the spread of human gastrointestinal pathogens.
-
Fluctuating asymmetry in Common Tern (STerna hirundo) chicks Varies with hatching order and clutch size
The Auk, 2009Co-Authors: Brian G. PalestisAbstract:ABSTRACT. Fluctuating asymmetry (FA), small random deviation from bilateral symmetry, often increases with stress during development. Common Terns (STerna hirundo) typically lay two to three eggs that hatch asynchronously. I predicted that C-chicks (last of three) should have greater FA than A- and B-chicks at hatching and that FA should be higher in chicks from smaller clutches, because of differences in parental quality. Tarsus length of newly hatched chicks was measured across three years, and middle toe length was measured in one year. Sample sizes exceeded 100 chicks in two of three years. Variation in tarsus FA with hatching order and clutch size was statistically significant in one year (P < 0.01) and nearly so in another (P < 0.10). No significant differences were present for toe FA. A-chicks from three-egg clutches appeared to have the lowest tarsus FA among categories of chicks in both years, and in one year they were significantly more symmetrical than B- and C-chicks from three-egg clutches. A...
-
the effect of siblings on nest site homing by Common Tern chicks a benefit of kin recognition
Waterbirds, 2001Co-Authors: Brian G. Palestis, Joanna BurgerAbstract:-Studies of kin recognition in birds have rarely tested its adaptive value. We tested whether sibling recognition helps Common Tern (STerna hirundo) chicks find their nests. The ability to discriminate the natal nest from neighboring nests is critical to survival in chicks of ground-nesting, colonial birds, such as the Common Tern. We temporarily moved 70 four-day old chicks 1 m from their nests and compared their ability to return home across the following treatments: siblings in natal nest, no chicks in nest, siblings in neighboring nest, and non-siblings in test chick's nest. With a sibling in the natal nest, test chicks returned within 20 min in 14 of 20 trials. In all other treatments, fewer than half of the chicks returned. When chicks did return, they typically did so within 5 min. Several additional factors may affect nest site homing, such as parental behavior, aggression by neighboring adults, and habitat type. To control for these factors, we restricted the dataset for analysis to 27 nests by excluding chicks led back to the nest by a parent, chicks attacked by neighboring adults, and nests on a rocky beach (most experiments were performed in grassy habitat). In the restricted dataset, seven of nine chicks with siblings in the nest returned. Two of five returned in the empty nest treatment, none of six with siblings at a neighboring nest returned, and one of seven with non-siblings in the nest returned. There was significant variation among treatments in the final distance of test chicks from their nests. Siblings appeared to affect nest site homing, even though parents usually returned quickly to the nest and were least likely to search for displaced chicks if siblings were home. We also tested the ability of singletons to return to the nest, using an identical protocol. Singletons returned to the nest in only two of 14 trials, in none of the six cases when the dataset was restricted. Received 15 September 2000, accepted 24January 2001.
Dominique Chabot - One of the best experts on this subject based on the ideXlab platform.
-
RESEARCH ARTICLE Population Census of a Large Common Tern Colony with a Small Unmanned Aircraft
2016Co-Authors: Dominique Chabot, Shawn R. Craik, David M. BirdAbstract:Small unmanned aircraft systems (UAS) may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests) coastal Common Tern (STerna hirundo) colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic Tern counts to ground nest counts in 45 plots (5-m radius) throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the fol-lowing day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972–0.989, P< 0.001) and regression coefficients ranged from 0.928–0.977 Terns/nest. Full colony aerial counts were 93.6 % and 94.0%, respectively, of the ground count. Varying visibility of Terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common Tern colonies following our method should yield population estimates in the 93–96 % range of ground counts. Although the Terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird research-ers and managers to consider taking advantage of this burgeoning technology
-
population census of a large Common Tern colony with a small unmanned aircraft
PLOS ONE, 2015Co-Authors: Dominique Chabot, Shawn R. Craik, David M. BirdAbstract:Small unmanned aircraft systems (UAS) may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests) coastal Common Tern (STerna hirundo) colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic Tern counts to ground nest counts in 45 plots (5-m radius) throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the following day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972–0.989, P < 0.001) and regression coefficients ranged from 0.928–0.977 Terns/nest. Full colony aerial counts were 93.6% and 94.0%, respectively, of the ground count. Varying visibility of Terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common Tern colonies following our method should yield population estimates in the 93–96% range of ground counts. Although the Terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird researchers and managers to consider taking advantage of this burgeoning technology.
-
Population census of a large Common Tern colony with a small unmanned aircraft
2015Co-Authors: Dominique Chabot, Shawn R. Craik, David M. BirdAbstract:Abstract: Small unmanned aircraft systems (UAS) may be useful for conducting high-precision, low-disturbance waterbird surveys, but limited data exist on their effectiveness. We evaluated the capacity of a small UAS to census a large (>6,000 nests) coastal Common Tern (STerna hirundo) colony of which ground surveys are particularly disruptive and time-consuming. We compared aerial photographic Tern counts to ground nest counts in 45 plots (5-m radius) throughout the colony at three intervals over a nine-day period in order to identify sources of variation and establish a coefficient to estimate nest numbers from UAS surveys. We also compared a full colony ground count to full counts from two UAS surveys conducted the following day. Finally, we compared colony disturbance levels over the course of UAS flights to matched control periods. Linear regressions between aerial and ground counts in plots had very strong correlations in all three comparison periods (R2 = 0.972-0.989, P < 0.001) and regression coefficients ranged from 0.928-0.977 Terns/nest. Full colony aerial counts were 93.6% and 94.0%, respectively, of the ground count. Varying visibility of Terns with ground cover, weather conditions and image quality, and changing nest attendance rates throughout incubation were likely sources of variation in aerial detection rates. Optimally timed UAS surveys of Common Tern colonies following our method should yield population estimates in the 93-96% range of ground counts. Although the Terns were initially disturbed by the UAS flying overhead, they rapidly habituated to it. Overall, we found no evidence of sustained disturbance to the colony by the UAS. We encourage colonial waterbird researchers and managers to consider taking advantage of this burgeoning technology. About the data: Raw aerial photos were captured in JPEG format by a Canon Powershot S90 10-megapixel camera mounted on an Aerial Insight AI-Multi electric fixed-wing UAS. The highest quality overlapping photos of each of the two islands comprising the Tern colony were then mosaicked using the PTGui panoramic stitching software. Photomosaics were then imported into ArcGIS and georeferenced with ground control points collected with a Trimble Pathfinder GPS at a series of yellow or orange plastic cones (visible in the imagery) marking the centre of plots in which ground nest counts were compared to aerial Tern counts. Overall disturbance levels on each of the two islands were scored on a scale of 0–2 from a distance by an observer at 30-second intervals throughout UAS flights as well as "matched" control periods starting 10 minutes following landing. For more information about this research or the data, please contact: dominique.chabot@mail.mcgill.ca