Habitat and weather conditions effects on long-term breeding population dynamics of five species of herons (Ardeidae) and Glossy ibis (Threskiornithidae) in the Valencian Community, Spain

Abstract

Habitat and weather conditions effects on long-term breeding population dynamics of five species of herons (Ardeidae) and Glossy ibis (Threskiornithidae) in the Valencian Community, SpainValencian wetlands include 65 % of the region's priority habitats and most are protected areas. Waterfowl populations are used as indicators of the state of these environments. We calculated the linear population trend by species, per wetland, of five Ardeidae and Plegadis falcinellus (Threskiornitidae) species using data from the annual census between 1984-2015 for 11 selected wetlands. We constructed a matrix with 42 habitat and meteorological variables, and evaluated the relation between these variables and population trends by a Correspondence Analysis. We found an increasing trend for most species. The populations of the L'Albufera de Vàlencia Natural Park (NP) differed significantly from the rest. Ardea cinerea, E. garzetta, B. ibis and A. ralloides would be associated with large areas, and also with swamps and rice fields, while A. purpurea and P. falcinellus would be related to environments characterised by rainfall and the level of protection in the area. Rice fields and water management have been important for establishing breeding colonies.

Effects of Rice Field Water Cycles on the Breeding Biology of Grey Heron (Ardea cinerea) and Conservation Implications

“…These changes have affected negatively both the quality of the feeding habitat for herons and other birds, as well as the reproductive success of some species such as the Little Egret ( Egretta garzetta ) or Cattle Egret ( Bulbucus ibis ) (Antón-Tello et al 2021, Forti et al 2021b). According to these studies, it is to be expected that the reproductive biology of the Grey Heron in L'Abufera de Vàlencia could have been affected, both in phenology and reproductive success, due to the effect of new practices in rice cultivation, which could also be related to the population declines that have been reported for the area (Generalitat Valenciana 2021, Forti et al 2021a). Over the last 30 years no further studies have been carried out on this breeding colony and how changes in the management of the rice field have influenced its breeding parameters, so a new assessment is needed.…”

“…2010. Similarly, the presence and extent of rice paddies has been related to population trends, colony size and reproductive success (Hafner et al 1987, Tourenq et al 2000, Fasola and Brangi 2010, Fujioka et al 2010, Ramo et al 2013, Forti et al 2021a, Fasola et al 2022). However, these aspects of waterbird biology are associated with the rice cultivation practices and rice flooding regime (Ibañez et al 2010, Cardarelli et al 2017, Forti et al 2021b.…”

“…The large extension of the rice field in L'Albufera has favored the establishment of 20,000-30,000 breeding pairs of different species of waterbirds, among which herons can be highlighted. L'Albufera de València is the third most important heron breeding site in Spain (Garrido et al 2012) and hosts 61% of the egrets and herons nesting in the whole Valencia Region, including the Grey Heron as the third most numerous species (Generalitat Valenciana 2018, Forti et al 2021a). This Grey Heron breeding colony, established in 1984 (Gómez-Lopéz et al 1985, Prósper 2000 has been the most important colony on the Spanish Mediterra-nean coast for the last 20 years (Campos et al 2001, Prieta and Campos 2003, Garrido et al 2012) and represents 48% of the nesting Grey herons in the Valencia Region (Generalitat Valenciana 2021) and 11% in Spain, according to the last published national census (Garrido et al 2012).The breeding population of L'Albufera had been experiencing a significant increase until 2013, reaching 1095 breeding pairs in 2000 (GeneralitatValenciana 2013).…”