Citation: Battisti, C.; Perchinelli, M.; Luiselli, L.; Dendi, D.; Vanadia, S. Cages Mitigate Predation on Eggs of Threatened Shorebirds: A Manipulative-Control Study. Conservation 2022, 2, 450–456. https://doi.org/10.3390/ conservation2030030 Academic Editor: Todd Fredericksen Received: 22 May 2022 Accepted: 9 July 2022 Published: 16 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Brief Report Cages Mitigate Predation on Eggs of Threatened Shorebirds: A Manipulative-Control Study Corrado Battisti 1, * , Marisa Perchinelli 1 , Luca Luiselli 2,3,4 , Daniele Dendi 2,3,4 and Sharon Vanadia 1 1 LTER (Long Term Ecological Research) Station, Protected Areas–Regional Park, Service, Città Metropolitana di Roma Capitale, Via Ribotta, 41, 00144 Rome, Italy; marisa.perchinelli@libero.it (M.P.); vanadia.sharon@gmail.com (S.V.) 2 Institute for Development, Ecology, Conservation and Cooperation, Via G. Tomasi di Lampedusa 33, 00144 Rome, Italy; l.luiselli@ideccngo.org (L.L.); d.dendi@ideccngo.org (D.D.) 3 Department of Applied and Environmental Biology, Rivers State University of Science and Technology, Port Harcourt P.M.B. 5080, Nigeria 4 Department of Zoology, University of Lomé, Lomé 01 BP 1515, Togo * Correspondence: c.battisti@cittametropolitanaroma.it; Tel.: +39-06-6766-3321 Abstract: Beach-nesting birds (plovers; Aves; Charadridae) are impacted by many natural and human-induced threats (e.g., people trampling, dogs, and natural predators). In this regard, the use of anti-predator cages on their nests is effective in order to mitigate some of these pressures (i.e., predation). To evaluate the efficacy of anti-predator cages and the causes of nest failure in a breeding site of two species (Charadrius alexandrinus and C. dubius), we carried out a control-experimental design, comparing false nests (n = 69) in cages (experiment; n = 30) with false nests without cages (control; n = 39). We carried out the study in three seasonal periods (May, June, and July), controlling predations after three periods (three, six, and nine days) since positioning, recording the frequency of eggs still present and evidencing any predation event. The percentage of residual eggs was significantly higher in experimental nests when compared to control nests in all recording periods. Considering 59 predation events on false nests, the most important predators were: in experimental nests (n = 21) the fox, Vulpes vulpes (47.6%), and in control nests (n = 38), the hooded crow, Corvus cornix (50%). Our data suggest that the use of anti-predator cages significantly limits predation on eggs and therefore is likely to increase the hatching success in these ground-nesting birds independently in the seasonal period. However, also in the presence of a cage, the fox is a relevant egg predator. Keywords: plovers; anti-predator cages; Vulpes vulpes; Corvus cornix 1. Introduction Ground-nesting birds are impacted by many natural and human-induced threats [1–3]. This plethora of threats is evident in birds nesting on coastal beaches (plovers; Aves; Charadridae) [4,5]. In coastal beaches, in addition to mechanical cleaning and accidental trampling, natural or human-related predators have been identified as the main factor in the low hatching success of plovers. However, few manipulative experiments have attempted to address this issue. In this regard, protection measures greatly increased hatching success [6]. In central Italy, two species of birds nest on the ground along the coast: the Kentish plover (Charadrius alexandrinus) and the Little Ringed Plover (Charadrius dubius), both of them being in rapid decline throughout Europe [7–9]). Both species nest on ephemeral environments of European conservation concern (shifting embryonic dunes) and are ex- posed in the breeding period to several threats, mainly linked to the pressures originated from the use of beaches by people (i.e., mechanical cleaning of the beaches, trampling, and domestic dogs; [10,11]) and by other natural events, especially predation, with crows, gulls, and foxes being the main predators [7,10–12]). The use of anti-predator cages has proved to Conservation 2022, 2, 450–456. https://doi.org/10.3390/conservation2030030 https://www.mdpi.com/journal/conservation