Glaucidium Brasilianum Research Articles

Ferruginous Pygmy-owl (Glaucidium brasilianum) predation on a mobbing Fork-tailed Flycatcher (Tyrannus savana) in south-east Brazil

I observed, and documented in detail, Ferruginous Pygmy Owl (Glaucidium brasilianum) predation on a mobbing Fork-tailed Flycatcher (Tyrannus savanna) in south-east Brazil. Events described in this account are supported with original photos. In addition to the predation event, I list 12 mobbing bird species that were alarmed by the presence of this raptor in the study area, including Trochilidae (Eupetomena macroura), Formicariidae (Formicivora rufa), Tyrannidae (Camptostoma obsoletum, Elaenia cristata, E. flavogaster, E. chiriquensis, T. savana, Myiarchus tyrannulus), Turdidae (Turdus leucomelas, T. amaurochalinus, T. rufiventris) and Emberizidae (Coryphospingus cucullatus). The Fork-tailed Flycatcher may represent 35-76.8% of the pygmy-owl body mass (41-80 g), which supports early reports about the predation on relatively large prey by this owl species. Although most authors have suggested that mobbing birds are subject to a low predation risk, this report and others confirmed that these events are not negligible and can be deadly dangerous to the mobbers, and conversely profitable to the raptor.

Ferruginous Pygmy-Owl (Glaucidium brasilianum) and Eastern Screech-Owl (Megascopes asio): New Hosts for Philornis mimicola (Diptera: Muscidae) and Ornithodoros concanensis (Acari: Argasidae)

While banding ferruginous pygmy-owls (Glaucidium brasilianum) and Eastern screech-owls (Megascops asio) in south Texas during 2004, we recorded Philornis mimicola (Diptera: Muscidae) and Ornithodoros concanensis (Acari: Argasidae) parasitizing nestlings. Inspection of nestlings revealed 54 P. mimicola and one O. concanensis. Inspection of nest material revealed 111 P. mimicola, including 57 puparia. The effect (e.g., blood loss, anemia) of these hematophagous parasites might have contributed to the demise of at least one Eastern screech-owl nestling. This is the first record of P. mimicola and O. concanensis parasitizing ferruginous pygmy-owls and Eastern screech-owls.

Population Trends and Implications for Monitoring Cactus Ferruginous Pygmy Owls in Northern Mexico

Although once described as common in lowland central and southern Arizona (Bendire 1888, Fisher 1893, Breninger 1898, Gilman 1909, Bent 1938), cactus ferruginous pygmy owls (Glaucidium brasilianum cactorum; hereafter, pygmy owls) have been extirpated throughout much of their former range in Arizona. As a result, this northernmost subspecies of ferruginous pygmy owls (Van Rossem 1937, Johnsgard 1988) are now listed as endangered by the U.S. Fish and Wildlife Service (USFWS 1997, Hardy et al. 1999). Immediately south of Arizona in northern Sonora, Mexico, pygmy owls occur primarily in desert-scrub and grassland vegetation communities where woodlands are near stands of large saguaro cacti (Carnegia gigantea) (Flesch 2003a). Because pygmy owls are thought to be abundant in northern Sonora, these populations may prove critical for recovery in Arizona as well as for long-term persistence of pygmy owls in the Sonoran Desert. Natural or facilitated dispersal of pygmy owls from Sonora may augment populations in Arizona, especially when combined with habitat management (USFWS 2003). Numerous threats to pygmy-owl habitat exist in northern Sonora, however, including woodcutting, vegetation clearing for agriculture or buffelgrass (Pennisetum ciliare), and overgrazing, and there are few regulatory mechanisms in place to protect habitat. Despite the importance of pygmy-owl populations in northern Sonora, there are currently no data on population trends or on design parameters for population monitoring. Therefore, between 2000 and 2004 we monitored relative abundance of pygmy owls in northern Sonora, estimated temporal variation in relative abundance, and assessed the efficacy of different sampling designs for monitoring population trends. Our goals were to assess population trends, determine environmental factors that explained variation in trends, and evaluate the statistical power of our monitoring program for future monitoring efforts.

Variation in DNA microsatellites of the ferruginous pygmy-owl (Glaucidium brasilianum)

Eleven polymorphic microsatellite loci were used to assess genetic variation in the ferruginous pygmy owl (Glaucidium brasilianum) from North America. Analysis of genotypic variation suggests restricted gene flow between pygmy-owl populations in Arizona-Sonora and Sinaloa, and Texas and the remaining states in Mexico. The Arizona-Sonora population showed signs of a recent genetic bottleneck, an observation supported by low population estimates for Arizona (13–117 individuals). Heterozygosity in Arizona, however, was equal to levels recorded throughout Mexico and Texas. Congruent patterns revealed by nuclear (microsatellites) and mitochondrial DNA that indicate Arizona-Sonora and Texas populations are distinct from adjacent populations in Mexico, thus emphasizing need for the design and implementation of separate management plans for recovery and conservation efforts. Revealing evidence of distinct groups within the pygmy-owl populations in North America, results from this study may be used to make management decisions for the recovery and conservation of this species.

Mitochondrial DNA Variation and Phylogeography of the Ferruginous Pygmy-Owl (Glaucidium brasilianum)

Sequences from the mitochondrial cytochrome b gene were used to examine patterns of variation within and among populations of the ferruginous pygmy-owl (Glaucidium brasilianum) from both North America (including populations from Mexico) and South America. As currently conceived, G. brasilianum is paraphyletic, with North American and South American clades representing two distinct groups that should be recognized as the distinct species G. ridgwayi and G. brasilianum, respectively. Within the G. ridgwayi clade, populations from Arizona, Sonora, and Sinaloa are genetically distinct and share no mitochondrial haplotypes with populations occurring in Texas and other regions of Mexico. According to nested clade analysis this separation may be the consequence of past fragmentation that predates the origin of the Sonora desert. In addition, gene flow between the Arizona/Sonora/Sinaloa populations and the Texas/other Mexico populations is practically nonexistent, with estimates being approximately one individual every 10 generations. Collectively, these data suggest that the Arizona/Sonora/Sinaloa clade should be recognized as either a distinct subspecies or phylospecies from the group containing populations in Texas and the remainder of Mexico. These data should be used as guidelines for pygmy-owl recovery and conservation, as they meet the recommendations of task 3 of the pygmy-owl recovery plan that lists genetic data as essential information for pygmy-owl management.

FERRUGINOUS PYGMY-OWLS: A NEW HOST FOR PROTOCALLIPHORA SIALIA AND HESPEROCIMEX SONORENSIS IN ARIZONA

While banding Cactus Ferruginous Pygmy-Owls (Glaucidium brasilianum cactorum) in Arizona, we removed three Protocalliphora sialia (Diptera: Calliphoridae) from the wing margin of one nestling. Subsequent inspection of nest material revealed an additional 119 Hesperocimex sonorensis (Hemiptera: Cimicidae), another hematophagous parasite. All nestlings (n = 3) fledged successfully, but on day 8 postfledging, two fledglings were found dead and one was missing. Although unsubstantiated, the subclinical effect (e.g., anemia) of these hematophagous parasites may have contributed to the fledglings' demise. This is the first published record of P. sialia parasitizing Ferruginous Pygmy-Owls and the first documented infestation of H. sonorensis for nesting Ferruginous Pygmy-Owls.

Development and characterization of microsatellite DNA primers for ferruginous pygmy‐owls (Glaucidium brasilianum)

AbstractTen polymorphic microsatellite loci were isolated and characterized for the ferruginous pygmy owl (Glaucidium brasilianum). Observed and expected heterozygosity were 0.07–0.85 and 0.1–0.88, respectively. Allele numbers ranged from five to 16 per locus.

Density and habitat use by owls in two Amazonian forest types

We conducted a short-term study on density and habitat use in an Amazonian owl assemblage. The census was conducted in terra-firme forest and black-water flooded forest or igapó forest. Six owl species were recorded, the Tropical Screech-owl (Otus choliba), the Tawny-bellied Owl (O. watsonii), the Black-banded Owl (Strix huhula), the Spectacled Owl (Pulsatrix perspicillata), the Ferruginous Pygmy-owl (Glaucidium brasilianum), and the Stygian Owl (Asio stygius). The most abundant species was the Tawny-bellied Owl (0.42 individuals/ha) followed by the Spectacled Owl (0.31 individuals/ha). Some species showed clear tendencies to use different habitats. The Tawny-bellied Owl was more abundant in terra-firme forest, while its congener, the Tropical Screech-owl, was much more common in igapó forest. The Stygian Owl and the Ferruginous Pygmy-owl were also recorded exclusively in the igapó forest census. These results indicate that terra-firme forest and igapó forest supported distinct owl assemblages. Our work and other studies suggest regional variability in owl density in Amazonia.

CACTUS FERRUGINOUS PYGMY-OWL IN ARIZONA, 1872–1971

Abstract The ferruginous pygmy-owl (Glaucidium brasilianum) has a wide geographic range centered on the Neotropics. At the northern edge of its distribution, 1 subspecies, the cactus ferruginous pygmy-owl (G. b. cactorum) reaches Texas and Arizona. However, in both states it has experienced important range and population declines. In Arizona in particular, the owl was originally described as common along several rivers and streams. There were many specimens collected and the subspecies was often mentioned in ornithological publications. Today, the cactus ferruginous pygmy-owl is found in low numbers in Arizona, and since 1997, it has been federally listed as endangered in that state. Determining when and why this owl began to decline sharply in numbers and range in Arizona has proven difficult. In retrospect, inadequate information apparently led to a lapse of several decades between the actual change in the population status and its recognition by ornithologists. Here we examine the most complete list of...

Development and distribution of cysts of an avirulent strain of Toxoplasma and the humoral immune response in mice.

An avirulent T. gondii strain isolated from a owl (Glaucidium brasilianum) produces randomly distributed cysts in the brain of mice which can survive to inocula as high as 1000 oocysts. Cysts appeared for the first time after 15 days of infection. Regarding to humoral immunity development due to our TCR-2 strain, detectable antibodies were found after 12 days of infection.

Important Birds from Blue Point Cottonwoods, Maricopa County, Arizona

The Salt River currently consists of four basic divisions: deeply channeled river from Roosevelt Lake upstream, irrigation reservoirs from that point downstream to Stewart Mountain Dam, dry river channel from Granite Reef Dam downstream to the confluence with the Gila River, and the fourth area, a short segment from Stewart Mountain Dam to Granite Reef Diversion Dam (about 10 miles long) representing what little remains of the native river. During the 1970's this portion is scheduled to be inundated by Orme Reservoir, part of the Central Arizona Project. Blue Point Cottonwoods, located approximately 2 miles upstream from the confluence of the Verde with the Salt River, is the only large stand of mature cottonwoods (Populus fremontii), with its attendant mesquite (Prosopis juliflora) understory, left on the entire Salt River. These cottonwoods will be covered by Orme Lake, thus virtually completing the extirpation of native riparian groves along the Salt River. This virgin grove extends for nearly a mile along the north side of the river. A narrow marsh of open water approximately one-half mile long, edged with arrowweed (Pluchea sericea) and salt-cedar (Tamarix sp.), and containing several dense stands of cattails (Typha domingensis) contributes to the diversity of the habitat. Azolla sp., a water fern unrecorded for central Arizona, grows profusely with duckweed (Lemna sp. ) in the marsh. Field work at Blue Point Cottonwoods has contributed much to our knowledge of birds in the central lowlands of Arizona. In the past, many important specimens and records were obtained from the area by Lyndon L. Hargrave, Allan R. Phillips, and Lewis D. Yaeger. Some of the more important records for the Salt River Valley include: the only specimens of the Ferruginous Owl (Glaucidium brasilianum) during this century (Hargrave; Phillips); the only specimen of the Common Crow (Corvus brachyrhynchos) (Phillips); the only Red-breasted Nuthatch (Sitta canadensis) specimens (Phillips and Yeager); the only nesting record of the Bewick's Wren (Thryomanes bewickii) (Phillips and Yeager); and the only Hutton's Vireo (Vireo huttoni) specimens (Phillips; Johnson and Simpson). The northernmost specimen for the Tropical Kingbird (Tyrannus melancholicus) was collected here by Simpson and Werner (Condor 60:68, 1958). While the following species nest at one or two other localities in the Salt River Valley, Blue Point Cottonwoods and the nearby river is the only area left that is both large enough and stable enough to support them all: Green Heron (Butorides virescens), Yellowbilled Cuckoo (Coccyzus americanus), Bell's Vireo (Vireo bellii), Yellow Warbler (Dendroica petechia), Yellowthroat (Goethlypis trichas), Summer Tanager (Piranga rubra), and Blue Grosbeak (Guiraca caerulea). Considering the ephemeral nature of the other habitats, the loss of Blue Point Cottonwoods may also mean the loss of most or all these species as breeding birds in the Salt River Valley. Our recent field work in this area has resulted in several additional distributional records of some interest. All specimens mentioned in the following species accounts are in the Johnson-Simpson-Werner (JSW) collection, now housed at Prescott College, Prescott, Arizona. Our thanks to Lyndon L. Hargrave and Allan R. Phillips for critical reading of the manuscript. Least Bittern. Ixobrychus exilis. According to Phillips, Marshall, and Monson (The birds of Arizona. Univ. Arizona Press, Tucson. 1964. p. 7), the only previously documented nesting of this species in Arizona was by Simpson and Werner (loc. cit.). Our specimen (JSW no. 925) was collected on 9 July 1969 in a dense stand of cattails in the marsh. It is a juvenile female with down on the legs, wings, neck, and head, and was accompanied by one or two other juveniles, presumably nest mates, and at least one adult. At least one additional adult was seen. The nest was secured on 20 July 1969 and is the first nest from Arizona for this species. Groove-billed Ani. Crotophaga sulcirostris. A female? (gonads shot), collected on 20 July 1969 (JSW no. 879) showed no fat and no molt. This is the second known extant specimen from the state (see Phillips et al., loc. cit.:46). Later, Bernard Roer informed us that he found another Groove-billed Ani at his bird farm in Phoenix on 11 July 1969 and donated it to the Phoenix Zoo. SHORT COMMUNICATIONS 379