Northern Saw-Whet Owls: Influence of Environmental Factors on Autumn Migration Dynamics
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Ectoparasite Activity During Incubation Increases Microbial Growth on Avian Eggs
Microbial Ecology https://doi.org/10.1007/s00248-017-1140-6 HOST MICROBE INTERACTIONS Ectoparasite Activity During Incubation Increases Microbial Growth on Avian Eggs G. Tomás1 & D. Martín-Gálvez1,2 & C. Ruiz-Castellano1 & M. Ruiz-Rodríguez1 & J. M. Peralta-Sánchez3 & M. Martín-Vivaldi3 & J. J. Soler1 Received: 20 December 2017 /Accepted: 28 December 2017 # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract While direct detrimental effects of parasites on hosts are relatively well documented, other more subtle but potentially important effects of parasitism are yet unexplored. Biological activity of ectoparasites, apart from skin injuries and blood-feeding, often results in blood remains, or parasite faeces that accumulate and modify the host environment. In this way, ectoparasite activities and remains may increase nutrient availability that may favour colonization and growth of microorganisms including potential pathogens. Here, by the experimental addition of hematophagous flies (Carnus hemapterus, a common ectoparasite of birds) to nests of spotless starlings Sturnus unicolor during incubation, we explore this possible side effect of parasitism which has rarely, if ever, been investigated. Results show that faeces and blood remains from parasitic flies on spotless starling eggshells at the end of incubation were more abundant in experimental than in control nests. Moreover, eggshell bacterial loads of different groups of cultivable bacteria including potential pathogens, as well as species richness of bacteria in terms of Operational Taxonomic Units (OTUs), were also higher in experimental nests. Finally, we also found evidence of a link between eggshell bacterial loads and increased embryo mortality, which provides indirect support for a bacterial-mediated negative effect of ectoparasitism on host offspring. -
<I>Carnus Hemapterus</I>
The large availabilityof suitablesites apparently facilitated non-repetitive selection. In the 1lth and 12th years,the femaleapparently failed to lay eggs.A newfemale appeared in 1976and laid eggsin 1977, 1978,and 1979,continuing the patternof selectingnew nestsites each year. However,two second(repeat) clutches were laid in previouslyused sites. Specifically,the 1978second clutch was laid in the 1977nest site, and the 1979second clutch was laid in the siteused for the first clutchin 1978.This pattern,i.e., the secondchoice of nestsite having been the firstchoice the yearbefore, I have termed the "fall-back-one" behavior. The onlyhistorical event common to both secondclutch sites is egg laying. I suggestthat preferencefor locationof the secondclutch is for a sitewhere egg laying and associatedbehavior have been ritualized in the nearestpast. Previous nestingsuccess at thatsite is incidental. If the "fall-back-one"behavior pattern is, in fact,common in peregrines,it should aid in predictingthe locationof secondclutches. I thankWayne Hanson for locatingnest sites in 1978,and John Hubbard and Wayne Pilz for reviewingearlier drafts. Literature Cited Herbert, R.A. and K.G.S. Herbert. 1965. Behaviorof PeregrineFalcons in the New York City Region.Auk 82:62-94. Porter, R.D. and C.M. White, 1973. The PeregrineFalcon in Utah, EmphasizingEcology and Competitionwith the Prairie Falcon.BYU ScienceBulletin, Bio. Series,Volume XVIII, No. 1.74 pp. Ratclff•e,D. 1980.The PeregrineFalcon. Buteo Books, USA and T. & A.D. PoyserLtd., Great Britain. 416 pp. Carnushemapterus NITZSCH FROM SWAINSON'S HAWK by Richard E. Fitzner Ecological SciencesDepartment Battelle, Pacific Northwest Laboratory Box 999 Richland, WA 99352 and Norman E. -
Brief Report Sex-Specific Diet Analysis of the Eurasian Eagle Owl in Finland
Ornis Fennica 91:195–200. 2014 Brief report Sex-specific diet analysis of the Eurasian Eagle Owl in Finland Heimo Mikkola* & Risto Tornberg H. Mikkola, Department of Biology, University of Eastern Finland, P.O.Box 1627, FI- 70211 Kuopio, Finland. * Corresponding author’s e-mail: [email protected] R. Tornberg, Department of Biology, P.O.Box 3000, FI-90014 University of Oulu, Fin- land Received 28 March 2014, accepted 17 June 2014 1. Introduction the smaller male that is mainly responsible for prey deliveries during the breeding season. Based on Birds of prey typically show reversed sexual size specimens found in good condition at the Zoologi- dimorphism (RSD), with females clearly larger cal museum of University of Oulu, Finland, fe- than males, for what purpose has aroused a pleth- male owls from Finland had an average weight of ora of hypothesis to explain it (see Krüger 2005). 2760 g (N = 50), while male weights averaged One of the earliest explanations has been avoid- 2200 g (N = 35). The RSD index of the Eagle Owls ance of competition between the mates (Temeles is 9.8 (calculated as in Amadon (1943) and Earhart 1985). Though avoidance of competition does not & Johnson (1970) by using the cube root of body explain the reversed nature of the sizes of the sexes mass to compare the indices of linear measure- it may be one mechanism to maintain it (Sunde et ments). This is the third highest value of all Euro- al. 2003, Krüger 2005). The Eurasian Eagle Owl pean owls (Mikkola 1982). It seems logical to hy- (Bubo bubo), hereafter termed Eagle Owl, is the pothesize that the heavier females may reduce in- largest owl in the world, a typical top-predator be- traspecific competition for food with males by tak- ing able to kill smaller birds of prey and owls ing larger prey than their smaller mates. -
Comparison of Food Habits of the Northern Saw-Whet Owl (Aegolius Acadicus) and the Western Screech-Owl (Otus Kennicottii) in Southwestern Idaho
Comparison of Food Habits of the Northern Saw-whet Owl (Aegolius acadicus) and the Western Screech-owl (Otus kennicottii) in Southwestern Idaho Charlotte (Charley) Rains1 Abstract.—I compared the breeding-season diets of Northern Saw- whet Owls (Aegolius acadicus) and Western Screech-owls (Otus kennicottii). Prey items were obtained from regurgitated pellets collected from saw-whet owl and screech-owl nests found in nest boxes in the Snake River Birds of Prey National Conservation Area in southwestern Idaho. A total of 2,250 prey items of saw-whet owls and 702 prey items of screech-owls were identified. Saw-whet owl diet was analyzed for the years 1990-1993; screech-owl diet was analyzed for 1992 only. The most frequently found prey items in the saw-whet owls diet were: Peromyscus, Mus, Microtus and Reithrodontomys; there were no significant differences among years. When saw-whet owl prey frequency data were pooled across years and compared to the 1992 screech-owl data, significant differences in diet were found. However, a comparison of the 1992 saw-whet prey frequency data with the screech-owl data showed no significant differences. In addition, the among year saw-whet owl prey biomass was analyzed, and again there were no significant differences. Micro- tus, followed by Mus, accounted for the largest proportion of prey biomass (by percent) in the diets of saw-whet owls for all years. When saw-whet owl prey biomass data were pooled across years and compared to the 1992 screech-owl prey biomass, significant differ- ences in diet were found. The 1992 saw-whet prey biomass com- pared to the 1992 screech-owl prey biomass also was significantly different. -
Boreal Owl (Aegolius Funereus) Surveys on the Sawtooth and Boise
BOREAL OWL (Aeqolius funereus) SURVEYS ON THE SAWTOOTH AND BOISE NATIONAL FORESTS BY Craig Groves Natural Heritage Section Nongame Wildlife and Endangered Species Program Bureau of Wildlife July 1988 Idaho Department of Fish and Game 600 S. Walnut St. Bow 25 Boise ID 83707 Jerry M. Conley, Director Cooperative Challenge Cost Share Project Sawtooth and Boise National Forests Idaho Department of Fish and Game Purchase Order Nos. 43-0261-8-663 (BNF) 40-0270-8-13 (SNP) TABLE OF CONTENTS Abstract ................................................................................................................................... Introduction ...........................................................................................................................1 Methods .................................................................................................................................2 Results and Discussion ..........................................................................................................6 Management Considerations ...............................................................................................13 Acknowledgments ...............................................................................................................15 Literature Cited ...................................................................................................................16 Appendix A .........................................................................................................................17 -
Aegolius Acadicus) in the Sierra Nevada Foothills
WINTER ECOLOGY OF NORTHERN SAW-WHET OWLS (AEGOLIUS ACADICUS) IN THE SIERRA NEVADA FOOTHILLS OF CALIFORNIA ________________ A Thesis Presented to the Faculty of California State University, Chico ________________ In Partial Fulfillment of the Requirements for the Degree Master of Science in Biological Sciences ________________ by Julie Shaw Summer 2014 WINTER ECOLOGY OF NORTHERN SAW-WHET OWLS (AEGOLIUS ACADICUS) IN THE SIERRA NEVADA FOOTHILLS OF CALIFORNIA A Thesis by Julie Shaw Summer 2014 APPROVED BY THE DEAN OF GRADUATE STUDIES AND VICE PROVOST FOR RESEARCH: _________________________________ E. K. Park, Ph.D. APPROVED BY THE GRADUATE ADVISORY COMMITTEE: _________________________________ Colleen Hatfield, Ph.D., Chair _________________________________ Tag Engstrom, Ph.D. _________________________________ Raymond J. Bogiatto, M.S. ACKNOWLEDGEMENTS I would have not been able to complete this thesis without the help and support of many people. First and foremost, Dr. Colleen Hatfield has been instrumental in keeping me on track with making progress. She especially helped keep me sane when I was feeling overwhelmed, and has provided guidance on both research and personal matters. I also would like to thank Dawn Garcia who has put forth hours of additional help for this project. She was an amazing ally in planning and executing much of the field logistics of my research, and this project would have never gotten off the ground without her. I would also like to thank the remainder of my thesis committee-Jay Bogiatto, MS and Dr. Tag Engstrom, for accepting the extra work of taking on another graduate student. Dr. Kathy Gray has also been extremely helpful with the “statistical challenges” of my thesis. -
The Ecology of Ectoparasitic Species Carnus Hemapterus on Nestlings Of
Slovak Raptor Journal 2010, 4: 45–48. DOI: 10.2478/v10262-012-0045-z. © Raptor Protection of Slovakia (RPS) The ecology of ectoparasitic species Carnus hemapterus on nestlings of common kestrel (Falco tinnunculus) in Bratislava K ekológii ektoparazitického druhu Carnus hemapterus na mláďatách sokola myšiara (Falco tinnunculus) v Bratislave Martin KAĽAVSKÝ & Barbora POSPÍŠILOVÁ Abstract: The time course and abundance of Carnus hemapterus on common kestrel’s nestlings depends on their age and the type of nest. Ectoparasites were found in 97% of nests and the majority of nestlings (83%) were observed to be infested between their 10th and 15th day of life. The highest infestation rate of Carnus hemapterus was recorded on 5- to 10-day old nestlings. We have confirmed that the Carnus hemapterus species feeds on blood; however no negative impact on nestlings and the breeding success of common kestrel was confirmed. Abstrakt: Doba výskytu a početnosť jedincov druhu Carnus hemapterus na mláďatách sokola myšiara závisí od veku mláďat a typu hniezda. Napadnutých bolo 97 % hniezd, pričom najviac mláďat (83 %) bolo napadnutých medzi 10. a 15. dňom života. Najväčší počet C. hemapterus bol zaznamenaný na mláďatách starých 5 až 10 dní. Potvrdili sme, že druh C. hemapterus sa živí krvou, ale negatívny vplyv na mláďatá a hniezdnu úspešnosť sokola myšiara sa nepotvrdil. Key words: hematocrit, hematophagy, abundance, Slovakia Martin Kaľavský, Department of Zoology, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, SK–842 15. E-mail: [email protected]. Barbora Pospíšilová, Department of Ecosozology and Physiotactics, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, SK–842 15. -
NORTHERN SAW-WHET OWL (Aegolius Acadicus) By: Marlene Cashen
Volume 26 Issue 60 June 2018 NORTHERN SAW-WHET OWL (Aegolius acadicus) By: Marlene Cashen Owls fascinate me, and I feel fortunate to be living in is plentful, it will cache food for later consumpton. It a state where, by my count, 15 species of owls either consumes pieces of larger prey in diferent meals over reside, irrupt to, or migrate through. Of course, there the course of several hours. Small, dark gray pellets are is no assurance that I will ever get to see all of these ejected with great difculty, accompanied by head and species, but there is always that glimmer of hope of a body twistng. chance encounter somewhere, sometme. And it ofen An interestng fact - the Northern Saw-whet Owl happens when you least expect it. In recent years, was frst discovered by European visitors in Nova Scota. I’ve had occasion to see a Northern Saw-Whet Owl It was so named because its alarm call, when threatened, in a friend’s yard in Lincoln County and then again in sounded like the whetng or sharpening of a mill saw. another friend’s yard in Spokane County. This species is widespread in Canada and all of the The Northern Saw-whet Owl is a permanent resident northern and western United States, but it experiences in our state, and birds from Canada migrate down high mortality. It is preyed upon by larger owls, Cooper’s into Washington’s lowlands east of the Cascades in Hawks, and Northern Goshawks. autumn. I’ll contnue to hope for more magical encounters It is small (6-1/2 to 8-1/2 inches, weighing 2.6 to with Northern Saw-Whet Owls and with the other 3.9 ounces – about the weight of an American Robin) elusive owls on my wish list. -
Central Valley Bird Club Bulletin
Central Valley Bird Club Bulletin Fall Migration of the Northern Saw-whet Owl in Northern Interior California 2016 Sacramento Purple Martin Status 2016 Central Valley Photo Highlights Vol. 20 No. 1, 2017 Fall Migration and Other Natural History Observations of the Northern Saw-whet Owl in Northern Interior California, 2005-2015 Dawn Garcia, 2620 Yard Street, Oroville, CA 95966. [email protected] ABSTRACT I and a group of volunteers captured and banded Northern Saw-whet Owls (Aegolius acadicus) during fall migration at the Big Chico Creek Ecological Reserve (Reserve) in Butte County, California from 2005-2015. Peak migration occurred between mid-October and mid-November. We banded 564 owls, and captured two owls originally banded at other stations, one from Montana and one from Iowa. Most captured owls were females over all years (70%) and during each banding year, as has been reported at other stations across the U.S. Similar numbers of adult owls (49.6%) and young owls (50.4%) were captured over all years but the ratio varied annually. Recapture rates were low; 30 individuals (5%) were recaptured during the same season they were banded, and 2% of owls were recaptured in subsequent years. The longest time between original banding and recapture was approximately three years. The two oldest recaptured individuals were four years old. Based on timing of first annual capture, hatch-year birds undertaking their first migration arrived at the Reserve on average three days earlier than older (after-hatch year) birds. Fall recaptures during the same season and during limited winter and spring mist-netting show that some individuals use the Reserve over the three seasons. -
2Nd Owl Symposium Population Densities of Northern Saw-Whet
2nd Owl Symposium Population Densities of Northern Saw-whet Owls (Aegolius acadicus) in Degraded Boreal Forests of the Southern Appalachians Timothy C. Milling1, Matthew P. Rowe1,2 , Bennie L. Cockerel1, Timothy A. Dellinger1, Johnny B. Gailes1, and Christopher E. Hill3 Abstract.—A disjunct population of the Northern Saw-whet Owl (Aegolius acadicus) breeds in the montane spruce-fir forests of the southern Appalachian Mountains. These forests are listed as the second most endangered ecosystem in the United States, having suffered from logging and massive fir die-off from the exotic balsam woolly adelgid. We used audio playbacks to compare densities of saw-whets prior to fir die-off (1968-1969) with those now (1993- 1994); numbers were almost identical, suggesting little if any impact from the adelgid. Extrapolation from our density estimates, however, show fewer than 500 pair of saw-whets in the southeastern popula- tion. Global warming, air pollution, outbreaks of new pests, and burgeoning recreational demands may further degrade these forests, leading to the possible extirpation of saw-whets from the southern Appalachians. The Northern Saw-whet Owl (Aegolius acadicus acadicus Gmelin) is a widespread and common owl in the forests of southern Canada and the northern United States (Cannings 1993, Johnsgard 1988). An apparent generalist, it has been found breeding in habitats as diverse as conifer plantations, deciduous forests, and cedar bogs (Cannings 1993, Johnsgard, 1988). Two potentially isolated populations occur in the eastern United States: a mid-Atlantic disjunct on the Allegheny Plateau of eastern West Virginia and western Maryland; and a southeastern disjunct in the southern Appalachian Mountains of western North Carolina, eastern Tennessee, and southwestern Virginia (fig. -
Boreal Owl: Wildlife Notebook Series
Boreal Owl The boreal owl (Aegolius funereus) is a common but rarely seen bird of the boreal forest in Alaska. It occurs throughout the forested areas of the Interior, upper Kobuk valley, Kodiak Island, and western Southcentral, including Prince William Sound out to the Alaska Peninsula as far as King Salmon. It is also occasionally found in Southeast Alaska. The species has a circumpolar distribution from eastern Canada to Alaska and from western Europe to Siberia. In North America it nests as far south as Colorado. The owl is a local resident and does not migrate although there may be food induced movements. Females may leave Alaska during the winter, but not much is known about their movements. General description: The boreal owl is named for its northern habitat, the boreal forest. In Europe the same owl is called Tengmalm's owl. It is one of three small owls in Alaska, about 8-9 inches long (20-23 cm) with a wing spread of 21-24 inches (53-61 cm). The other small owls are the Saw-whet owl which lives in southcentral coastal and southeastern areas and the pygmy owl which only lives in southeastern Alaska. Female boreal owls average 6.4 ounces (179 gms) and are larger than males at 3.8 ounces (106 gms). It has a dull white facial disk with almost black upper corners and raised white eyebrows, giving it a surprised look. The top of the head has numerous small white spots. The bill is light-colored. The boreal owl is rarely seen because it is mainly nocturnal and solitary. -
Review of Technical Knowledge: Boreal Owls
Chapter 9 Review of Technical Knowledge: Boreal Owls Gregory D. Hayward, Rocky Mountain Forest and Range Experiment Station, Laramie, WY 82070 INTRODUCTION are strongly related to local forest conditions and prey populations. The boreal owl (Aegolius funereus), known as In contrast with studies in Europe, habitat use has Tengmalm's owl in Eurasia, occurs throughout the been emphasized in the few investigations in North holarctic in boreal climatic zones. This medium-size America. Studies on the two continents have gener- owl (100-170 g) occupies boreal and subalpine for- ated few data with which to contrast the biology of ests in an almost continuous circumboreal distribu- the species between continents. Therefore, the basis tion that extends from Scandinavia eastward across for inferring North American biology and ecology the northern forests of Siberia and from Alaska across based on European results is unclear. The variabil- Canada to the Atlantic (Dement'ev and Gladkov ity witnessed in Europe suggests caution. However, 1954). On each continent, disjunct populations oc- to the degree that variation in Europe follows geo- cur in mountains south of the broad transcontinen- graphic, climatic, or habitat gradients, a more sound tal boreal forest populations (Cramp 1977, Voous basis upon which to build inferences for North 1988). Boreal owls in the mountain regions of Eu- America is possible. rope and Asia have long been recognized as isolated The paucity of scientific knowledge from North resident breeding populations, whereas in North America necessitates reliance on the extensive America, breeding status was only recently docu- knowledge accumulated in Europe for portions of mented in the mountains of the western United the assessment.