A true “migrant trap”: Boerhavia (Nyctaginaceae) entanglement as a recurring cause of avian entrapment and mortality

Bird Entanglement and Mortality by Fruits of the Zapallo Caspi Tree Pisonia Zapallo in the Dry Chaco, Argentina

“…In addi>on, plants such as the Arc7um burdocks (Asteraceae) have been men>oned in various reports and have caught at-ten>on because of their impact on migrant and local passerines in Manitoba (Canada) (Underwood & Underwood 2013, Harms 2022). Moreover, Palmer et al (2009) and Wilder (2019) reported entanglements by Boerhavia spiderlings (Nyctaginaceae) in Arizona (USA) of a Western Screech-Owl Megascops kennico@i, a Mourning Dove Zenaida macroura, and various passerines. Here, we document, for the first >me, the entanglement and mortality of birds by a plant in con>nental South America, specifically by the dry fruits of the zapallo caspi tree Pisonia zapallo, Nyctaginaceae.…”

“…Most reports on bird entanglement by plant structures involve one or a couple of individuals per finding (i.e., Donelly & Webber 1974, Palmer et al 2009. Previous reports have performed systema>c searches that summed up to 39 birds (Hinam et al 2004, Underwood & Underwood 2013, Wilder 2019) in successive regional visits. Others have provided important compila>ons of cases in different regions (Püschel & Birkhold 2000, Hager et al 2009, Harms 2020) that helped to build a comprehensive vision of this phenomenon.…”