The Andean Condor (Vultur gryphus) is a culturally iconic wildlife symbol for the South American Andes, but is naturally found at very low population densities, and is increasingly threatened. Using the Range Wide Priority Setting methodology, we (a group of 38 Andean Condor experts) updated the Andean Condor historical range (3,230,061 km²), systematized 9998 Andean Condor distribution points across the range, and identified geographic areas for which there was expert knowledge (66%), including areas where Andean Condors no longer occur (7%), and geographic areas where condors are believed to range, but for which there was not expert knowledge about condor presence (34%). To prioritize conservation action into the future and identify existing Andean Condor population strongholds, we used expert knowledge to identify 21 of the most important areas for the conservation of the species (i.e., Andean Condor Conservation Units [ACCUs]) that cover 37% of the revised historical range, and range in size from 837 km² to 298,951 km². In general, ACCUs were relatively small in the northern portion of the range in Venezuela, Colombia, Ecuador, and northern Peru, and significantly larger in the central and southern portion of the range in Peru, Bolivia, Chile, and Argentina, reflecting the reduced and narrower historical range in the northern portion of the range, as well as increased threats. Andean Condors can fly extremely long distances and so the populations of many neighboring ACCUs are probably still functionally connected, although this situation also underlines the need for integrated and large-scale conservation efforts for this species. As a function of the Range Wide Priority Setting results, we make recommendations to ensure population connectivity into the future and engage a wide range of actors in Andean Condor conservation efforts.

Flight behavior of soaring birds depends on a complex array of physiological, social, demographic, and environmental factors. California Condors (Gymnogyps californianus) rely on thermal and orographic updrafts to subsidize extended bouts of soaring flight, and their soaring flight performance is expected to vary in response to environmental variation and, potentially, with experience. We collected 6298 flight tracks described by high-frequency GPS telemetry data from five birds ranging in age from 1 to 19 yr old and followed over 32 d in summer 2016. Using these data, we tested the hypothesis that climb rate, an indicator of flight performance, would be related to the topographic and meteorological variables the bird experienced, and also to its age. Climb rate was greater when condors were flying in faster winds and during environmental conditions that were conducive to updraft development. However, we found no effect of age on climb rate. Although many of these relationships were expected based on flight theory, the lack of an effect of age was unexpected. Our work expands understanding of the relationship condors have with the environment, and it also suggests the potential for as-yet unexplored complexity to this relationship. As such, this study provides insight into avian flight behavior and, because flight performance influences bird behavior and exposure to anthropogenic risk, it has potential consequences for development of conservation management plans.

The southern limit of the Golden Eagle's (Aquila chrysaetos) breeding range in North America is Mexico, where the eagle is the national symbol yet designated as a threatened, high priority species for conservation action. Movement information needed for conserving Mexico's Golden Eagles is sparse; knowledge of dispersal from natal areas is essential to understand the eagle's ecology and help provide for its management. Using satellite telemetry data, we analyzed movements of three males and one female from central Mexico during their first year of life; we documented (1) timing and distance of initial dispersal movements, (2) total distance traveled and maximum distance from natal site by month of age following fledging, and (3) size of areas (based on 95% adaptive local convex hulls) across which eagles ranged following initial dispersal. Individual eagles dispersed from their natal areas between mid-September and mid-November, at 6–8 mo of age. Monthly total distance traveled by males reached approximately 350–1350 km at 8–11 mo; the female's peak monthly travel was 3000 km, at age 7 mo. Monthly proximity to natal sites by individuals at ages 8–12 mo was relatively constant, averaging 17.9 km (SD = 5.7) to 129.1 km (SD = 11.3). After dispersal, the monthly ranging areas overall increased during the first year of life for all eagles, especially the female, due mainly to multiple long-distance excursions. Our data suggest that movement behavior of juvenile Golden Eagles from Mexico is mostly similar to that of conspecifics from nonmigratory populations elsewhere. Our study may help serve as a foundation for future work to better understand movement dynamics and resource selection by Mexico's Golden Eagles.

Fisheries managers used the fish toxicant rotenone to eradicate an undesirable brown bullhead (Ameiurus nebulosus) population and all other fish species at Hyatt Reservoir, Oregon, on 12 October 1989. This 4-yr study (1988–1990, 1992) compared effects of that rotenone project on Ospreys (Pandion haliaetus) nesting at Hyatt Reservoir and nearby Howard Prairie Reservoir (untreated reference)—the latter a reservoir where both brown bullheads and hatchery-released rainbow trout (Oncorhynchus mykiss) prospered. Because Hyatt Reservoir was treated after Osprey fall migration in 1989, the first 2 yr (1988 and 1989) yielded pretreatment information: number of Osprey pairs was unchanged and reproductive rates were similar and consistent at the two reservoirs. Yearling fish (200–250 mm) were restocked at Hyatt Reservoir in the spring of 1990 and Ospreys returned each year following rotenone treatment, with no decline in the number of occupied or active nests. The negative effect of the rotenone treatment on Ospreys was short-term, resulting in reduced reproductive rates (young/occupied nest, young/active nest, and young/successful nest) during the first nesting season posttreatment, although hatching rates were not affected. Osprey dive success and prey delivery rates declined sharply in 1990, leading to competition for food among siblings and brood reduction. Osprey reproductive rates and prey delivery rates at Hyatt Reservoir in both 1990 and 1992 remained below the extremely high pretreatment rates, but within the range required for population stability. Serious adverse effects of the fish loss on Osprey reproduction were minimized by: (1) the delay of the rotenone application until after breeding season, (2) the restocking of the treated reservoir in the following spring with some larger (yearling) fish (though the timing was late), (3) the maintenance of a supplemental feeding program for a nesting pair of Bald Eagles (Haliaeetus leucocephalus), which minimized kleptoparasitism on Ospreys, and perhaps most important (4) the presence of nearby water bodies, where Osprey obtained some fish in the 1990 and 1992 breeding seasons.

Landscape configuration can influence the distribution of species across multiple spatial scales. The primary factors related to this process are connectivity, the size and position of habitat patches, and edge effects. These factors together determine the overall fragmentation of a landscape, which in turn influences species occurrence. Although some species show a negative response to fragmentation, others benefit from it. Potential effects may act over multiple spatial scales, possibly with contrasting effects on species occurrence. We chose the Tawny Owl (Strix aluco), a ubiquitous and generalist species, to study the influence of fragmentation on species occurrence and to identify relevant landscape metrics, using multi-scale hierarchical modelling. Between 2016 and 2018, we recorded Tawny Owls on 64 sampling sites located in a forested landscape. We used a space-for-time substitution in the framework of occupancy modelling to assess Tawny Owl responses to landscape fragmentation. We found that the Tawny Owl is widespread in the study area. Its distribution across the landscape (larger spatial scale) was related to a heterogeneous configuration of forest patches, while high connectivity of coniferous forest influenced its occurrence at a smaller spatial scale (sites). Overall, the Tawny Owl prefers landscapes with well-connected forest patches and an uneven patch distribution in the surrounding area.

The Mexican Spotted Owl (Strix occidentalis lucida; hereafter spotted owl) is discontinuously distributed in the United States and Mexico. It is an understudied raptor and categorized as near threatened, with populations in rapid decline. Defining the distribution of the spotted owl can help delineate priority areas for monitoring and research. Using the Maxent algorithm, with seven climatic variables and 153 owl presence records, we generated the potential distribution of spotted owl in Mexico. Our distribution model had high predictive accuracy and defined potential areas in the Sierra Madre Occidental, Sierra Madre Oriental, and the Transverse Neovolcanic Belt. These areas were concentrated in the states of Durango, Zacatecas, Jalisco, Aguascalientes, and Chihuahua, as well as within four protected natural areas. Four weather variables contributed 81.8% to the model's prediction: mean diurnal temperature range (BIO 2, 33.5%), maximum temperature of the warmest month (BIO 5, 30.4%), mean temperature of the coldest quarter (BIO 11, 10.5%) and the amount of precipitation in the wettest month (BIO 13, 7.4%). We recommend population monitoring in areas of climatic suitability predicted by the model to improve knowledge about the status of the Mexican Spotted Owl.

Although variation in microscopic plumulaceous (downy) feather characters is known to be useful in taxonomic identifications of birds, the conserved characters unique to most avian orders remain understudied. We examined plumulaceous feather characters (morphometric and observed pigmentation patterns [qualitative]) within three avian families (Cathartidae, Pandionidae, Accipitridae) occurring in North America that often require taxonomic identification based on incomplete or fragmentary remains. We found significant quantitative differences among these three families for measurements of barbule length, node width, average number of nodes per barbule, and internode length. We observed additional differences in pigmentation patterns and spine distribution at nodes. Differences in pigment patterns and intensity are diagnostic for distinguishing Black Vulture (Coragyps atratus) from Turkey Vulture (Cathartes aura) within Cathartidae. Further observed differences of a higher percentage of spined structures present at node junctions along the length of barbules are diagnostic of Pandionidae. Within Accipitridae, pigmentation patterns and pigment intensity separate Swallow-tailed Kite (Elanoides forficatus) and White-tailed Kite (Elanus leucurus) from all other taxa; and barbule length, together with average nodes per barbule is unique to Northern Harrier (Circus hudsonius) in the families examined in this study. Although significant differences in a combination of microscopic feather characters among species were seldom observed in this study, family level differences were consistently documented. Results support the use of a suite of microscopic characters in combination with macroscopic feather features, geographic distributions, molecular methods, and other circumstantial evidence to aid in the identification of species of birds from feathers.

American Kestrels (Falco sparverius) are declining across much of North America, yet the initial timing of the population decrease is unclear. In an attempt to elucidate when kestrel declines began, we examined historical descriptions of abundance within the northeastern United States. Within The Peregrine Fund's research library, we found 54 descriptions of kestrel abundance in northeastern states dating from 1839 to 2013. Our analysis indicates a cubic trend in descriptions of kestrel abundance with a peak occurring in 1951. After that peak, the population began its current decline, yet the population appears to have been stable beforehand. That the current decline is apparent in our data set lends credence to our methodology and suggests that populations were likely secure until approximately 1951. Our results thus suggest that populations of American Kestrels in the northeastern United States began declining before systematic monitoring began in 1966. Future research should thus examine what environmental changes occurred around the early- to mid-20th century in the northeastern USA to cause population declines of American Kestrels.

Diurnal raptors were counted during their southward migration in autumn of 2019 at Kenting National Park, southern Taiwan, an important hawkwatch site along the East-Asian Oceanic Flyway. Observations were conducted from 1 September to 31 October 2019 in the morning hours, but the observation period was extended to 1400 H whenever large numbers of raptors passed the site before noon. A total of 329,559 individuals of 14 migratory raptor species was recorded. The Chinese Sparrowhawk (Accipiter soloensis) and Gray-faced Buzzard (Butastur indicus) made up 78.3% (257,971 birds) and 21.6% (71,045 birds) of the total, respectively. The number of Chinese Sparrowhawks increased significantly when we extended the survey duration from 1200 H to 1400 H (paired t-test, t = 2.44, P = 0.04), but the number of Gray-faced Buzzards did not (t = 1.94, P = 0.09). Thus, Chinese Sparrowhawks may continue passing the site en route to the Philippine Islands in the afternoon hours, whereas Gray-faced Buzzards usually stop migrating in early afternoon, at least under certain conditions. How prevailing wind conditions along the East-Asian Oceanic Flyway in autumn shape the different migratory strategies of these two hawk species requires further study.

Studies of territorial and courtship behavior are lacking for many tropical raptors. From 2006 to 2009, using observations that were not time-limited, we studied the territorial and courtship behaviors of the White-necked Hawk (Buteogallus lacernulatus) and the Mantled Hawk (Pseudastur polionotus) in Rio Doce State Park in eastern Brazil. We observed White-necked Hawks and Mantled Hawks engaged in aerial displays on 67 and 13 occasions, respectively. Display behaviors performed by White-necked Hawks were characterized by 1–4 undulations followed by aerial swoops and spirals. Territorial and/or courtship behaviors of Mantled Hawks were characterized by the male and female performing thermal or horizontal gliding together and diving in spirals while frequently emitting a series of long and short whistles. This study presents the first formal descriptions of the aerial territorial/courtship displays of these rare forest-dwelling raptors.

The Rufous-legged Owl (Strix rufipes) is the southernmost Strix owl species and its breeding ecology remains little known. We report new observations on the species' breeding ecology, including clutch size, egg size, duration of the incubation and nestling periods, and nestling diet. We conducted our observations on nests found during the summers of 1999 through 2004 in a forestry landscape of central Chile, dominated by Monterey pine (Pinus radiata) plantations with intermixed fragments of native southern beech (Nothofagus) forests. Clutch size was two eggs (n = 2 nests), with one egg larger than the other (mean = 48.8 × 40.1 mm). The incubation period was 30 d and the nestling period 34 d. We analyzed 10 pellets from nestling owls and identified 45 prey items, mostly dominated by large beetles, grasshoppers, and rodents (native and exotic). This information, though based on a limited number of nests, provides baseline ecological data that can inform future studies.

Raptor biologists have successfully used backpack-type harnesses to attach transmitters to a wide range of raptor species for research. As part of a graduate research project with Gray Hawks (Buteo plagiatus) in south Texas, we attached harnesses to 58 individuals and experienced problems with seven birds removing the harnesses and with all females covering the solar panels of the OrniTrack-10 GPS-GSM transmitters, preventing them from functioning properly. We appear to have resolved these issues by trimming nape feathers (short-term solution), switching to a different harness material, stitching through the knots, switching to a different brand of glue, and using a transmitter with an elevated solar panel for females, which are typically larger than males.

Artificial perches can attract raptors to farmland, where the raptors perform an ecosystem service by consuming insect or rodent pests; however, such perches have not enjoyed widespread use. We used an improved camera trap installation method to record birds on perches, and to test perch height preference of raptors and other species. Our study area was in a mosaic agriculture system, the typical farming environment in Asia. Our “double-branch” perches consisted of a main pole with a branch at the top and in the middle, 8 and 4 m from the ground, respectively. Each branch was equipped with a camera trap, with the focus adjusted to close range. From April to July 2020, the installations at five different crop fields provided a total of 83,740 photographs with birds, including 27 avian species. Photographs of raptors and insectivorous birds accounted for 80.1% to 99.7% in each field. The most frequently recorded raptors were the Black-winged Kite (Elanus caeruleus) and the Collared Scops-Owl (Otus lettia). The most frequently recorded insectivorous birds were the Black Drongo (Dicrurus macrocercus) and the Brown Shrike (Lanius cristatus). The kites preferred to stand on the upper branches, whereas the owls and most of the insectivorous birds tended to choose the lower branches. By our method, numerous clear photographs of birds can be obtained and used to analyze visit frequency, activity patterns, and captured prey. Moreover, we showed that different species used artificial perches of different heights. Artificial perches could be more widely used for enhancing and quantifying avian ecosystem services, and promoting raptor-friendly farming.

The Himalayan Griffon (Gyps himalayensis) is listed as near threatened and its populations are poorly monitored. During late May and early June of 2013, 2014, and 2016, we resurveyed transects that were originally sampled 2002–2006. These transects were within the Annapurna region of Nepal. From 2010 through 2020, we also monitored a breeding colony of Himalayan Griffons within the Arghakhanchi District of Nepal. The number of non-adults, adults, and total Himalayan Griffons counted along the transects approximately doubled from the previous counts. At the colony, the number of breeding pairs and young fledged increased during the study (yearly growth rate [r] = 0.049 and 0.089, respectively). The number of offspring fledged per breeding pair also increased (r = 0.040). Our results are encouraging, but we only surveyed a small portion of the global population and over a relatively short time period. We recommend expanded and coordinated population monitoring for this species across its range.

Although vulture feeding stations are a widely used tool for vulture conservation in many regions worldwide, there has been some confusion about their functions and this is reflected in the range of terminology used. The origin of food supply at provisioning sites (both for in situ and ex situ situations) and the goals of feeding station managers (ranging from purely conservation of vultures to the necessity for carcass disposal) are two key aspects that are often neglected. We review the definitions and nomenclature for the provision of predictable anthropogenic food for vultures and vultures' role in sanitation in the landscape. We propose that “supplementary feeding stations for vultures” (SFSV) defines a particular case and this term should only be applied when a station has vulture conservation goals and a food supply coming from outside of the landscape (ex situ). We introduce the term “recycling station with vultures” (RSV) for cases when the goal is the elimination of carcasses and the food is sourced in situ (natural, NRSV) or ex situ (supplementary food, SRSV). This clarification of goals and terminology for feeding stations worldwide could have important consequences for the understanding and assessment of vulture conservation and management actions, among researchers and conservationists and also importantly among stakeholders and wider society.

Red-legged Seriemas (Cariama cristata) and Black-legged Seriemas (Chunga burmeisteri) are two exclusively South American species that inhabit open and sparsely forested areas. Seriemas have been recently included with the raptors based on ecological and evolutionary evidence. Viewing seriemas as raptors is nontraditional and might be controversial. Therefore, further information regarding the evolution, taxonomy, morphology, and ecology of these birds will clarify the validity of their consideration as raptors. Here we present a review of the published information on seriemas, and discuss future research for these newly adopted raptors. To conduct our review, we developed a systematic map and searched all databases available within Clarivate Analytics' Web of Science, performed a keyword search of Google Scholar, and included the corresponding bibliographies from the Birds of the World website. We reviewed 98 studies, and found that the Red-legged Seriema was the subject of more studies than the Black-legged Seriema. Overall, Brazil and Argentina were the site of most studies. The majority of studies examined physiology (48), followed by behavior (37), threats to the survival of these species (36), and demography (27), while smaller numbers of studies examined stressors (e.g., habitat changes, causes of mortality and injury such as predation, hunting, etc.) (20), and conservation actions (10). Patterns of study categorizations were similar for both species, and the distribution of studies across months was also fairly even for both species. This is the first study to systematically review and assess the published information on seriemas. Our results show the topics and locations on which past studies have focused, and highlight potentially fruitful avenues for future research. Although threats to seriemas have been identified, these have not been thoroughly assessed; thus, their extent and effects on seriema populations were difficult to ascertain. Future research should focus on testing existing hypotheses regarding seriema feeding, vocalization, social, and territorial behaviors, while documenting natural history. Researchers should build on past investigations while establishing programs to monitor the conservation status of seriemas across their ranges.