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1 September 2012 Ectoparasites of American Kestrels in Northwestern New Jersey and Their Relationship to Nestling Growth and Survival
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American Kestrel (Falco sparverius) populations have been declining throughout much of North America during recent decades. To determine if the ectoparasite burdens of nestlings may be a contributing factor, we examined broods of kestrels in nest boxes in northwestern New Jersey. Our objectives were to identify and quantify the arthropod ectoparasites of nestlings, and to determine if removing these parasites from nestlings would increase kestrel nesting success. Of 26 broods we examined, we randomly chose 13 and manually removed from the nestlings all visible arthropods during three visits, when nestlings were age 5–7, 10–12, and 15–17 d old; we handled the 11 control broods similarly but did not remove arthropods. Both the experimental and control broods were measured and banded at age 20–22 d, and all visible arthropods were collected from both groups. Of 1767 arthropod specimens collected, 1679 (95.0%) were Carnus hemapterus (Diptera: Carnidae). Our observation of the next most abundant parasite, Ornithonyssus sylviarum (northern fowl mite, Acari: Macronyssidae; 46 specimens), was apparently the first record of the American Kestrel as host. The remaining 42 specimens included 9 other kestrel parasites (4 species) and 33 nonparasites (19 species). C. hemapterus loads increased as nestlings aged, were highest at age 10–12 d, and declined thereafter. At age 20–22 d, control broods had significantly higher loads of C. hemapterus and other parasites. However, we detected no significant differences in nestling wing length, tail length, body mass, body mass/wing length (an index of nestling condition), or nestling survival. Thus, we found no evidence that ectoparasite removal would be an effective strategy in increasing the nesting success of American Kestrels in this study area.

Durante las últimas décadas, las poblaciones de Falco sparverius han disminuido a lo largo de la mayor parte de América del Norte. Para determinar si la carga de ectoparásitos de los pichones puede ser un factor que contribuye a la disminución, examinamos las nidadas de F. sparverius en nidos caja en el noroeste de Nueva Jersey. Nuestros objetivos fueron identificar y cuantificar los ectoparásitos artrópodos de los polluelos y determinar si la remoción de estos parásitos de los pichones incrementa el éxito de nidificación de la especie. De las 26 nidadas que examinamos, escogimos 13 al azar y quitamos manualmente todos los artrópodos visibles de los pichones durante tres visitas, cuando las edades de los polluelos eran de 5–7, 10–12 y 15–17 días. Manipulamos las 11 nidadas de control de manera similar pero no les quitamos los artrópodos. Tanto la nidada experimental como la de control fueron medidas y anilladas a los 20–22 días de edad y todos los artrópodos visibles fueron colectados en ambos grupos. De 1767 especímenes de artrópodos colectados, 1679 (95.0%) pertenecieron a la especie Carnus hemapterus (Diptera: Carnidae). La observación del siguiente parásito más abundante, Ornithonyssus sylviarum (Acari: Macronyssidae; 46 especímenes) fue, aparentemente, el primer registro para F. sparverius como hospedador. Los 42 especímenes restantes incluyeron otros nueve parásitos de F. sparverius (4 especies) y 33 individuos no parásitos (19 especies). Las cargas de C. hemapterus aumentaron a medida que los pichones crecían hasta los 10–12 días de edad y a partir de entonces disminuyeron. A la edad de 20–22 días, las nidadas de control presentaron cargas significativamente mayores de

Mark J. Lesko and John A. Smallwood "Ectoparasites of American Kestrels in Northwestern New Jersey and Their Relationship to Nestling Growth and Survival," Journal of Raptor Research 46(3), 304-313, (1 September 2012).
Received: 29 July 2011; Accepted: 1 March 2012; Published: 1 September 2012

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