An effective nest trap for female Yellow-headed Blackbirds

Abstract

Capturing breeding female blackbirds using mist nets and food-baited traps can be challenging because nets are difficult to set in wetland habitats and females feed preferentially on insects. Given the problems associated with other trapping methods, we designed a highly effective nest trap that allowed us to successfully capture targeted female Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) at our wetland study sites in North Dakota. From 15 May to 16 July 2004, we captured 56 of 59 (95%) targeted females during incubation and eight of 18 (44%) targeted females with nestlings, and were also able to recapture 12 of 16 females (75%). Based on these results, we recommend using our trap to capture female blackbirds during incubation rather than during the nestling period. The nest trap is easy and inexpensive to construct and is light and easy to carry through dense wetland vegetation. In addition, the trap's large diameter and wire construction provide the flexibility needed to trap at sites where the density of vegetation varies. This trap has also been used to capture female Red-winged Blackbirds (Agelaius phoeniceus) and could potentially be used to trap females of other species of wetland-breeding icterids, including Common Grackles (Quiscalus quiscula). SINOPSIS El capturar hembras en estado reproductivo de individuos de Xanthocephalus xanthocephalus utilizando redes de niebla y trampas con cebo, pudiera ser un ejercicio de gran reto, dado el caso de que las aves se alimentan de insectos y las redes son dificiles de montar y manejar en anegados. Dados los problemas asociados con otros metodos disenamos una trampa efectiva que nos permitio capturar con exito individuos particulares en un estudio que llevamos a cabo en Dakota del Norte. Del 15 de mayo al 16 de julio de 2004, capturamos 56 de 59 individuos deseados (95%) durante el periodo de incubacion, ademas a 8 de 18 hembras (44%) con pichones. Tambien recapturamos 12 de 16 (75%) de las hembras. Basandonos en estos resultados, recomendamos el uso de nuestra trampa durante la fase de incubacion, en vez de la epoca de cria. La trampa es facil de construir, liviana, facil de transportar (a traves de un anegado denso) y de bajo costo. Ademas, el diametro de la trampa y su construccion en alambre ofrecen la flexibilidad necesaria para colocarla en sitios en donde la densidad de la vegetacion resulte variable. Este tipo de trampa tambien ha sido utilizada para atrapar hembras de Agelaius phoeniceus y puede ser, potencialmente, utilizada para atrapar hembras de otras especies de icteridos que anidan en anegados, incluyendo a Quiscalus quiscula.