Diet selection of introduced black ratsRattus rattus L. in relation to plant availability on Berlenga Island, Portugal / Préférence alimentaire des rats noirs introduits Rattus rattus L. en relation avec la disponibilité de la flore sur l’île de Berlenga, Portugal

• Published in: Ecologia mediterranea
• Main Authors: Nascimento, Tania, Oliveira, Nuno, Fagundes, Ana Isabel, Tejada-Baena, Carlos, Luís, Antonio
• Format: Article in Journal/Newspaper
• Language: English
• Published: Marseille : Institut Méditerranéen de Biodiversité et d'Ecologie 2019
• Subjects: rodents; trophic position; food preference; native flora; seed predation; rongeurs; niveau trophique; préférence alimentaire; flore indigène; prédation des graines; envir; socio; Rattus rattus
• Online Access: https://doi.org/10.3406/ecmed.2019.2072; https://www.persee.fr/doc/ecmed_0153-8756_2019_num_45_1_2072

Introduced rodents cause major effects on insular local flora and fauna. The presence of black rats (Rattus rattus) on Berlenga Island can be a threat to endemic and native species, especially for plants. Understanding the trophic position of black rats is essential for management efforts and conservation actions. With this purpose, we studied the feeding preferences and food selection of black rats during winter and spring, when food resources are higher. Diet was accessed by analyzing the stomach and intestinal contents of 23 black rats, and plant availability estimated through sampling 561 plots of 2×2m. Black rats diet is mainly composed of plants (94.1%), with 13 species identified. The remaining 5.9% was composed by invertebrates, with 7 distinct groups. All preyed plants were native, but no endemic species were found in stomach contents. Seeds were the main food item, possibly affecting the plant community by both its predation and dispersion. Evidences of bird predation were found. Remains of feathers were present in ~ 22% of the analyzed stomachs. We verified that black rats are not entirely generalists but intermediate selective consumers, and the high availability of a food source is not the only factor for prey selection. Les rongeurs introduits ont un impact fort sur la faune et la flore locales insulaires. La présence de rats noirs (Rattus rattus) sur l’île de Berlenga peut constituer une menace pour les espèces endémiques et indigènes, en particulier pour la flore. Comprendre la position trophique des rats noirs est essentiel pour engager les efforts de gestion et les actions de conservation des écosystèmes. Dans ce but, nous avons étudié leurs préférences et la sélection de proies par les rats noirs en hiver et au printemps, lorsque les ressources alimentaires sont les plus abondantes. Le régime alimentaire a été étudié en analysant les contenus stomacaux et intestinaux de 23 rats noirs. La détermination de la disponibilité floristique via l’étude de 561 parcelles de 2 × 2 m a également été ...