Journal of Raptor Research最新文献

{"title":"Community Reserves Serve as Refugia Sites for Cavity-Nesting Owls in Northeast India","authors":"Aritri Sarkar, S. S. Sailas, S. Babu, P. Karunakaran, H. N. Kumara, Sureshmarimuthu Shanmugavel, Padmanaban Pramod","doi":"10.3356/JRR-21-48","DOIUrl":"https://doi.org/10.3356/JRR-21-48","url":null,"abstract":"Abstract. Community Reserves, which are Community Conserved Areas, form the majority of the Protected Area Network in northeast India. Because this biodiverse region is threatened by a variety of anthropogenic activities, Community Reserves likely serve as refugia sites for stenotopic, cavity-nesting species such as some owls. To test this hypothesis, we conducted nocturnal surveys in 11 Community Reserves comprised of primary or secondary forest and outside Community Reserves in Meghalaya state, northeast India. We then used nonparametric tests to assess differences in the occurrence of owls among these three categories. We found that on average, occurrence of owls was higher inside Community Reserves. Inside Community Reserves with secondary forests, we found significantly higher occurrence of the Asian Barred Owlet (Glaucidium cuculoides) and Collared Scops-Owl (Otus lettia), while in Community Reserves with primary forest, we found significantly higher occurrence of the Brown Wood-Owl (Strix leptogrammica), a declining old-growth forest specialist. Hence, Community Reserves are serving as sites of refugia for owls in northeast India. However, anthropogenic pressures such as logging, shifting cultivation, and developmental activities threaten the forests of the region. Old-growth forests are also scarce in Meghalaya and were present in only two of the Community Reserves. Therefore, we find it of prime importance to conserve these reserves, especially those containing primary forests, and to allocate more areas as Community Reserves in the region. Resumen. Las Reservas Comunitarias son Áreas Conservadas por las Comunidades locales y constituyen la mayor parte de la Red de Áreas Protegidas en el noreste de India. Debido a que esta región biodiversa está amenazada por una variedad de actividades antropogénicas, las Reservas Comunitarias probablemente sirvan como sitios de refugio para especies estenotópicas que anidan en cavidades, como algunos búhos. Para probar esta hipótesis, realizamos censos nocturnos en 11 Reservas Comunitarias compuestas por bosques primarios o secundarios, y fuera de las Reservas Comunitarias, en el estado de Meghalaya, al noreste de India. Utilizamos pruebas no paramétricas para evaluar las diferencias en la presencia de búhos entre estas tres categorías. Encontramos que, en promedio, la presencia de búhos era mayor dentro de las Reservas Comunitarias. Dentro de las Reservas Comunitarias con bosques secundarios, encontramos una presencia significativamente mayor de Glaucidium cuculoides y Otus lettia, mientras que en las Reservas Comunitarias con bosque primario encontramos una presencia significativamente mayor de Strix leptogrammica, un especialista de bosques maduros en declive. Por lo tanto, las Reservas Comunitarias están sirviendo como sitios de refugio para los búhos en el noreste de India. Sin embargo, las presiones antropogénicas como la tala, el cambio en los cultivos y las actividades de desarrollo amenazan lo","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"1 1","pages":"22 - 29"},"PeriodicalIF":1.7,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75378075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preliminary Evidence of Anticoagulant Rodenticide Exposure in American Kestrels (Falco sparverius) in the Western United States","authors":"E. Buechley, D. Oleyar, Jesse L. Watson, Jennifer Bridgeman, S. Volker, D. A. Goldade, C. Swift, B. Rattner","doi":"10.3356/jrr-22-18","DOIUrl":"https://doi.org/10.3356/jrr-22-18","url":null,"abstract":"\u0000 Although there is extensive evidence of declines in the American Kestrel (Falco sparverius) population across North America, the cause of such declines remains a mystery. One hypothesized driver of decline is anticoagulant rodenticide (AR) exposure, which could potentially cause mortality or reduced fitness. We investigated AR exposure in wild American Kestrels in Utah, USA. We collected and tested for AR residues in liver samples (n = 8) from kestrels opportunistically encountered dead and in blood samples (n = 71) from live wild kestrels, both nestlings and adults. We found high detection rates in both tissues. Adult kestrels were more likely to exhibit exposure than juveniles sampled in nests. Three-quarters (six of eight) of tested liver samples from adult kestrels exhibited evidence of AR exposure. Additionally, liver samples (n = 19) opportunistically collected from seven species of raptors within our study area had detectable levels of AR residues, with seven of eight raptor species evidencing exposure; across all raptors, five ARs were detected in liver samples, with brodifacoum the most prevalent, being found in over half (14 of 27) of samples. Over half (7 of 12) of the blood samples from adult kestrels had detectible levels of ARs, while only one of 59 juvenile nest samples tested positive. The difference in exposure rates between adults and juveniles could indicate differential exposure pathways by age class. Based on these findings, we recommend that ARs be further investigated as a potential cause of kestrel declines. Future research could focus on expanding sampling to provide sufficient sample sizes to test for potential nonlethal effects of AR exposure (e.g., fecundity, nesting success), identifying potential exposure pathways, and developing methods for passive sampling of ARs in excreta.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"52 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76916376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproductive Success Increases with Age in American Kestrels, Especially in Males","authors":"Emilie R. Snyder, John A. Smallwood","doi":"10.3356/jrr-22-15","DOIUrl":"https://doi.org/10.3356/jrr-22-15","url":null,"abstract":"\u0000 Age-related differences in reproductive or breeding success, as measured by clutch size, hatching rate, nestling survival, and number of fledglings produced, have been well documented in many species of birds. The experience gained through successive breeding attempts can improve foraging abilities, survival skills, access to resources through social dominance, and familiarity with each stage of reproduction. We examined 696 breeding attempts by American Kestrels (Falco sparverius) from a population that bred in nest boxes in northwestern New Jersey from 1995 to 2021. We tested the hypothesis that older kestrels have greater breeding success than those in their first breeding season. Clutch size, nestling survival rate, and the number of fledglings varied significantly and positively with the age of one or both parents. These trends were significantly correlated with the date of clutch initiation; older birds initiated clutches earlier than those in their first breeding attempt. However, after we controlled for laying date, older birds still had larger clutch sizes, higher nestling survival rates, and greater numbers of fledglings. The relationship between age and breeding success was more pronounced for males than females. This difference is consistent with the behavioral roles of each sex during a breeding attempt. After laying a clutch, females perform most of the incubation and brood young nestlings. In contrast, males provide food for females prior to egg laying and throughout incubation, and to the entire family until the nestlings no longer are brooded by the female. Females paired with older males had significantly greater body mass index values (weight/wing chord) than those paired with second-year males. Pairs where both adults were older had significantly greater breeding success than mixed or young pairs, and we never observed an older female paired to a male during his first breeding attempt.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"07 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86083215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Factors Associated with American Kestrel (Falco sparverius) Nest Box Occupancy and Reproductive Success in an Agricultural Landscape","authors":"J. Kolowski, L. Morrow, Jill Morrow","doi":"10.3356/jrr-21-64","DOIUrl":"https://doi.org/10.3356/jrr-21-64","url":null,"abstract":"\u0000 The American Kestrel (Falco sparverius), a small, cavity-nesting falcon that breeds across most of North America, is experiencing an apparent population decline across much of the United States that has yet to be sufficiently explained. With landscape change as a potential factor, the association of landscape composition with kestrel reproduction may assist not only in managing declines but also in improving the effectiveness and efficiency of nest box programs, which can bolster local populations and support monitoring and research efforts. We monitored 163 unique American Kestrel nest boxes over a 12-yr study period (2008–2019) in western Virginia to investigate the factors influencing kestrel reproductive success and we documented relatively high rates of both box occupancy (80%) and nest success (78.9%). In a study area dominated by both high- and low-intensity agriculture, we focused on identifying patterns in land cover composition that may limit reproductive success and associated each box with land cover composition metrics at four spatial scales. Generalized linear mixed models indicated nest boxes with a lower proportion of developed land within 500 m, and a higher proportion of crops and pasture/hay within 3 km were more likely to be occupied by kestrels. Although probability of kestrel nest success increased with reduced proportions of developed land within 100 m, the primary factors influencing success were clutch initiation date and the presence of European starlings (Sturnus vulgaris), with earlier nesting and the absence of starling activity resulting in higher nest success. Overall, cover-type associations with nest success and box occupancy were not strong and establishment of nest boxes in targeted kestrel habitat, while likely maximizing reproductive output, limits research opportunities to identify critical land cover thresholds for the species.","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"24 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73526044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Use, and Misuse, of the Subterminal Black Tail Band to Age Female American Kestrels","authors":"John A. Smallwood, T. Ely, Carole E. Hallett","doi":"10.3356/JRR-22-45","DOIUrl":"https://doi.org/10.3356/JRR-22-45","url":null,"abstract":"Abstract. The tail feathers of female American Kestrels (Falco sparverius) are rufous-brown with black bands down the entire length. There is considerable individual variation in the width and shape of these bands. The width of the most distal (subterminal) black band relative to the width of the next proximal black band may change with age. Published empirical data show that juvenal rectrices have either narrow or, less commonly, wide subterminal bands while adult rectrices consistently have wide subterminal bands. Here we review the literature about this characteristic and discuss how it has been used, and potentially misused, to age female American Kestrels. Resumen. Las plumas de la cola de las hembras de Falco sparverius son de color marrón rojizo con bandas negras en toda su longitud. Existe una variación individual considerable en el ancho y la forma de estas bandas. El ancho de la banda negra más distal (subterminal) en relación con el ancho de la siguiente banda negra proximal puede cambiar con la edad. Los datos empíricos publicados muestran que las rectrices de los juveniles tienen bandas subterminales estrechas o, con menos frecuencia, anchas, mientras que las rectrices de los adultos tienen, de forma consistente, bandas subterminales anchas. Aquí revisamos la literatura sobre esta característica y discutimos cómo ha sido utilizada, y potencialmente mal utilizada, para determinar la edad de las hembras de F. sparverius. [Traducción del equipo editorial]","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"258 1","pages":"1 - 5"},"PeriodicalIF":1.7,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77046767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproductive Rate of the Red-Headed Falcon (Falco chicquera) in Surendranagar District, Gujarat, India","authors":"N. Bhatt","doi":"10.3356/JRR-21-73","DOIUrl":"https://doi.org/10.3356/JRR-21-73","url":null,"abstract":"Abstract. I evaluated the breeding biology of Red-headed Falcon (Falco chicquera) by documenting 39 breeding attempts in Surendranagar district of Gujarat, India, from 2006 to 2021. Across years, the Mayfield estimated seasonal nest survival was 0.900 ± 0.016 (95% CI), and productivity was 2.5 ± 1.4 (95% CI) fledglings per breeding attempt. Prey deliveries recorded during the study were exclusively birds, 71% of the order Passeriformes. Of the 39 breeding attempts in 18 territories, 26 nests were on high tension electricity transmission pylons and 13 were in trees. I provide the first baseline data for comparing and evaluating reproductive rate of this species in different environments across the Indian subcontinent and elsewhere. Resumen. Evalué la biología reproductiva de Falco chicquera documentando 39 intentos reproductivos en el distrito de Surendranagar de Gujarat, India, de 2006 a 2021. A lo largo de los años, la supervivencia estacional de los nidos, estimada por el método de Mayfield, fue de 0.900 ± 0.016 (IC del 95%), y la productividad fue de 2.5 ± 1.4 (95% IC) volantones por intento reproductivo. Las entregas de presas registradas durante el estudio fueron exclusivamente aves, con el 71% pertenecientes al Orden Passeriformes. De los 39 intentos reproductivos en 18 territorios, 26 nidos fueron colocados sobre postes eléctricos de alta tensión y 13 en árboles. Proporciono los primeros datos de referencia para comparar y evaluar la tasa reproductiva de esta especie en diferentes ambientes en el subcontinente indio y en otros lugares. [Traducción del equipo editorial]","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"25 1","pages":"75 - 80"},"PeriodicalIF":1.7,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85611064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using the Motus System to Track Post-Breeding Dispersal of American Kestrels Nesting in Minnesota, USA","authors":"Mark S. Martell, A. Archer, Amber Burnette, Mary W. Lee, Frank J. Nicoletti, Kristin A. L. Hall","doi":"10.3356/JRR-22-27","DOIUrl":"https://doi.org/10.3356/JRR-22-27","url":null,"abstract":"Abstract. Understanding breeding ground dispersal, migratory timing and routes, and winter distribution of birds that are facing population declines, such as the American Kestrel (Falco sparverius), can provide insight into their life history traits and potentially inform management decisions. We used Lotek NanoTags and CTT LifeTags to track American Kestrels breeding in three locations in Minnesota, USA, across the Motus network. We tagged nine juvenile American Kestrels in July and August 2020 and 24 more kestrels between April and August 2021 (21 adults and three juveniles). We subsequently detected 15 (45%) of the 33 birds tagged. Eleven birds (33%) were detected while still on their breeding grounds; detections on the breeding grounds after tag deployment lasted an average of 64.3 d (SD = 59.7 d) and 19.9 d (SD = 13.2 d) for adults and juveniles, respectively. Two of the three juvenile males left their natal area 44 d after fledging and the third left 68 d after fledging. However, the average date of departure did not differ by age or sex. Twelve of 33 tagged birds (39%) were detected at post-breeding ground locations during flybys (25 events) or stopovers (2 events), and they all followed a relatively consistent migratory pathway from Minnesota through Iowa and Missouri. However, a lack of Motus receiver stations south of Missouri limited our ability to determine wintering areas. The use of the Motus system to determine dispersal and migratory pathways of American Kestrels, while currently limited in the central part of North America by the availability of receiver stations, is a valuable tool in furthering our understanding of American Kestrel life cycles and possibly revealing causes of the species' population decline in North America. Resumen. Comprender la dispersión en las zonas de reproducción, el momento y las rutas migratorias y la distribución invernal de las aves que se enfrentan a una disminución de la población, como Falco sparverius, puede proporcionar información sobre sus rasgos de historia de vida y potencialmente contribuir a las decisiones de gestión. Usamos Lotek NanoTags y CTT LifeTags para rastrear individuos de F. sparverius que se reproducen en tres lugares de Minnesota, EEUU, a través de la red Motus. Marcamos nueve juveniles de F. sparverius en julio y agosto de 2020 y 24 individuos más entre abril y agosto de 2021 (21 adultos y tres juveniles). Posteriormente detectamos 15 (45%) de las 33 aves marcadas. Once aves (33%) fueron detectadas mientras aún se encontraban en sus áreas de reproducción; las detecciones en las áreas reproductivas después de la colocación de las marcas alcanzaron un promedio de 64.3 d (DE = 59.7 d) y 19.9 d (DE = 13.2 d) para adultos y juveniles, respectivamente. Dos de los tres machos juveniles abandonaron su área natal 44 d después de emplumar y el tercero lo hizo 68 d después de emplumar. Sin embargo, la fecha promedio de partida no difirió por edad o sexo. Doce de las 33 aves marcadas (39%","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"7 1","pages":"1 - 10"},"PeriodicalIF":1.7,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75355256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Golden Eagles Nesting in an Urban Setting in a Canary Island Date Palm Tree, San Jose, California","authors":"Philip G. Higgins, S. Menzel","doi":"10.3356/JRR-21-57","DOIUrl":"https://doi.org/10.3356/JRR-21-57","url":null,"abstract":"Golden Eagles (Aquila chrysaetos) are uncommon residents in the densely populated south San Francisco Bay area, California, USA, especially within the city of San Jose (Bousman 2007). Nesting Golden Eagles have not been reported within the city limits since 1892 (Barlow 1893, California Department of Fish and Wildlife 2021). Contributing factors for this absence might include limited foraging and nesting habitat. Golden Eagles typically nest on cliffs and tall trees (Katzner et al. 2020) such as pine trees (Pinus spp.), oaks (Quercus spp.), and eucalyptus (Eucalyptus spp.; Bousman 2007). Regionally, they nest in remote areas at higher elevations in the adjacent ranges and foothills to the east and west of San Jose. Here we describe our observations of Golden Eagles nesting in a Canary Island date palm tree (Phoenix canariensis) on the valley floor in approximately 202 ha of open grasslands adjacent to the San Jose–Santa Clara Regional Wastewater Facility (RWF) within the city of San Jose (37.42469468N, 121.95074798W). A pair has nested in the same stand of trees there for five consecutive years, 2018–2022. The RWF is located north of Highway 237 and south of the Don Edwards National Wildlife Refuge at the southern end of the San Francisco Bay. The ridgeline of the Diablo Range is approximately 10 km to the east and the Santa Cruz Mountains ridge is approximately 24 km to the west of the site. The ruderal grassland adjacent to the RWF formerly provided a safety zone (hereafter, bufferlands) between the RWF and surrounding residential areas when large quantities of chlorine were stored at the facility as part of its normal operations. At present, the bufferlands provide foraging and nesting habitat for several raptor species including White-tailed Kites (Elanus leucurus), American Kestrels (Falco sparverius), and Burrowing Owls (Athene cunicularia). Since 2013, we have conducted yearround monthly surveys for Burrowing Owls at this location. We conducted surveys during a 4–5 hr time-period, and we performed other tasks during additional opportunistic site visits during the peak of the Burrowing Owl breeding season (April–August). During these surveys, we occasionally observed a single Golden Eagle foraging, usually during fall and winter. However, starting November 2017, we regularly observed a pair of Golden Eagles hunting for California ground squirrels (Otospermophilus beecheyi) and roosting in a small stand of Canary Island date palm trees located in the center of the site at an elevation of approximately 10 m above mean sea level. We confirmed a large nest among the fronds of the biggest palm tree (diameter at breast height: 108 cm) in May 2018. The nest was approximately 10 m above ground on the northeast side of the tree. We inspected the nest structure using binoculars and examined nest material we found on the ground in January 2021 after a high-wind event. The nest was constructed primarily of eucalyptus branches, most likely from two tree","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"18 1","pages":"114 - 115"},"PeriodicalIF":1.7,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86093982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Largely Nocturnal Kangaroo Rats Preyed Upon by Diurnal American Kestrels in New Mexico","authors":"D. Stahlecker","doi":"10.3356/JRR-22-33","DOIUrl":"https://doi.org/10.3356/JRR-22-33","url":null,"abstract":"As secondary cavity nesters, American Kestrels (Falco sparverius) adapt readily to nest boxes, so most documentations and enumerations of their prey have been from boxes during the approximately 30-d nestling period (Smallwood and Bird 2020). Sherrod (1978), summarizing six North American studies of American Kestrel prey by numbers, not mass, showed that invertebrates (74%) were most often captured, though mammals (16%), birds (9%), and reptiles (1%) were also taken. However, in 2017 at 975 m elevation in the semi-arid southern Great Plains of northwestern Texas, reptiles (74.8%) were by far the most frequent kestrel prey recorded on motion-activated video cameras, while invertebrates, mammals, and birds made up 18.2%, 4.4%, and 2.9%, respectively (Boal et al. 2021). Of 187 mammals documented, 121 (64.7%) recorded were .42 g and ,75 g (Boal et al. 2021), which represented 38– 68% of the mass of an average 110-g American Kestrel male (Smallwood and Bird 2020). Thus, the capability of this species to repeatedly capture prey up to two-thirds their own mass has been previously reported. From 1995 to 2020 American Kestrels occupied one (n1⁄4 14) or both (n1⁄4 11) of two nest boxes 250 m apart in the Eldorado at Santa Fe (ESF) subdivision 15 km south of Santa Fe, New Mexico, USA. They successfully fledged young on 35 of 36 (97.2% fledging success) attempts during 50 (72% occupancy rate) nest box years; the second box became available in 1997. ESF is at 2000–2100 m elevation in piñon pine (Pinus edulis)-juniper (Juniperus spp.) savannah with groundcover dominated by blue grama (Bouteloua gracilis); it was converted from ranchland to housing starting in 1972. Large lots (0.5–1 ha), limits to yard/garden size, and extensive greenbelts resulted in a largely intact, ungrazed, natural habitat and prey base. Prey deliveries to one box regularly observed were approximately 67% (n1⁄4 29) reptilian between 1996 and 2009, though observations were opportunistic rather than standardized (Stahlecker and Cartron 2010). I visited nest boxes to band nestlings 2–3 wk after I began to see prey deliveries. I usually ignored the conglomeration of prey remains, particularly legs and carapaces of invertebrates, to complete the banding in a minimal time. However, on 8 July 2018, I found five tails of Ord’s kangaroo rats (Dipodomys ordii) in Box 1, and an additional tail in Box 2. The typical mass of D. ordii is approximately 52 g (Jones 1985), or 47% of the mass of an average American Kestrel male. The young in Box 1 were 13–15 d old and those in Box 2 were 7–10 d old, based on a photographic guide (Griggs and Steenhof 1993). The D. ordii were likely brought to the boxes by the males, as females forage very little early in the nestling period, but instead brood, feed, and defend the nestlings (Smallwood and Bird 2020). No species of kangaroo rat has, to my knowledge, been previously reported as prey of the American Kestrel. All 20 species in the genus Dipodomys are primarily ","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"504 1","pages":"1 - 3"},"PeriodicalIF":1.7,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77072070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracking Device Attachment Methods for American Kestrels: Backpack Versus Leg-Loop Harnesses","authors":"K. Biles, J. Bednarz, S. Schulwitz, Jeff A. Johnson","doi":"10.3356/JRR-22-13","DOIUrl":"https://doi.org/10.3356/JRR-22-13","url":null,"abstract":"Abstract. The American Kestrel (Falco sparverius) is a small falcon whose population is declining across North America, but drivers of this decline have yet to be identified. Conservationists have called for greater understanding of kestrels' migratory connectivity to identify potential causes of decline that may occur during various parts of their annual cycle. For many bird species, the most common and direct way to determine migratory connectivity is by attaching a tracking device that documents their locations over time. However, American Kestrels present a challenge when attaching tracking devices due to their small size and aggressive biting capabilities. We used two attachment methods (backpack and leg-loop harnesses) commonly used for raptors on a wintering population of American Kestrels in north Texas to test whether there were differences in observed return rates the following year. Of 20 American Kestrels fit with devices, significantly more of the kestrels fit with backpack harnesses were observed the following winter than the birds fit with leg-loop harnesses. Eight of the 10 kestrels we fit with backpacks were observed to return to their winter territories compared to only two of 10 kestrels fit with leg-loops. Overall return frequency data of kestrels with both harnessing methods (50%, n = 20) was similar to the frequency we observed on marked birds without devices (52%, n = 190), though this was heavily skewed due to the high return of birds with backpack harnesses (80%). Although our sample size was limited, the disparity between the return rates of birds with the two harness types suggests that backpack harnesses are the preferred method of attaching tracking devices to American Kestrels, and also potentially to similar small raptor species. Resumen. Falco sparverius es un pequeño halcón cuya población está disminuyendo en América del Norte, pero aún no se han identificado los factores que causan esta disminución. Los conservacionistas han abogado por una mayor comprensión de la conectividad migratoria de esta especie para identificar las posibles causas de disminución que pueden ocurrir durante varias partes de su ciclo anual. Para muchas especies de aves, la forma más común y directa de determinar la conectividad migratoria es colocando sobre ellas un dispositivo de seguimiento que documente sus ubicaciones a lo largo del tiempo. Sin embargo, F. sparverius presenta un desafío al momento de fijar los dispositivos de seguimiento, debido a su pequeño tamaño y su capacidad para picotear agresivamente. Usamos dos métodos de fijación (arneses de mochila y pélvicos), comúnmente empleados para aves rapaces, en una población de F. sparverius invernante en el norte de Texas, para probar si había diferencias en las tasas de retorno observadas al año siguiente. De los 20 individuos equipados con dispositivos, se observaron significativamente más ejemplares provistos con arneses de mochila en el invierno siguiente que aves provistas con a","PeriodicalId":16927,"journal":{"name":"Journal of Raptor Research","volume":"74 ","pages":"1 - 10"},"PeriodicalIF":1.7,"publicationDate":"2022-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72439995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}