Seed dispersal in Andalusian olive groves by frugivorous birds

All methodological information and farms and landscape characteristic information can be found in Rey et al (2021). Characterization of the avian seed dispersers and the seeds they mobilizes by mist-netting: From September 2019 to March 2020, we conducted bird mist-netting sessions in the 20 study olive farms monthly. Birds trapping was carried out for 3 h in each session (between mid-morning and noon). For each farm, two simultaneous capture zones, one in the olive field and the other in SNWH patches were considered, with a distance of 150 meters between zones. In each zone (habitat), we set two mist-nets of 12 × 2.5 meters and a mesh size of 16mm (24 linear meters of the net in total per zone). In each mist-net zone, a sound call that emitted songs of the frugivorous species present was arranged at random to attract birds. A 1-m wide strip of mosquito net was placed on the ground beneath the mist nets to collect the seeds excreted by the birds while they were trapped in the net. Once a bird was released from the net it was immediately introduced in a cloth bag with a paper cone located inside until the moment of seed collection/identification. All birds were kept in the cloth bags for 1 h, then ringed and released. For each individual captured, the total number of seeds of each species collected under the net and in the collector was recorded. Mobilised seeds to seed fall traps: - Seed_trap_2018: To determine the probability of seed deposition into different habitats within the olive farm and to characterize seed rain, we used plastic plant pots of 40 cm diameter and 20 cm depth as seed fall traps. Traps were covered with a 1 × 1 cm wire mesh to avoid seed predation by micro mammals and perforated on their base to drain rainwater. 18 seed fall traps were placed per farm in three different types of habitats (6 traps per habitat): beneath the olive tree canopy, beneath the canopy of isolated overtopping non-olive trees serving as perches to birds within the olive field, and within seminatural woodland habitat remnants. Traps were always set hanging from branches of trees and/or tall scrubs. Traps were active for 17 months, between October 2018 and March 2020 in 9 localities. We collected the trapped seeds periodically (every 3 months, with monthly-bimonthly checks to make sure that the traps were active). - Seed_trap_2021: in this case, we used plastic plants trays of 57 x 42 cm and 10 cm depth as seed fall traps. Traps were covered with a 1 × 1 cm wire mesh to avoid seed predation by micro mammals and perforated on their base to drain rainwater. 30 seed fall traps were placed per farm in seminatural woodland habitat remnants below fleshy- fruited shrub, other shrubs and perches. The traps were active for 6 months, between June 2021 and March 2022 in 12 localities. We collected the trapped seeds monthly.

Proyecto SUMHAL, LIFEWATCH-2019-09-CSIC-13, POPE 2014-2020.

Our aim was to characterize the seeds of fleshy fruit species mobilized by avian frugivores in the olive grove farms of the Guadalquivir valley in Andalusia (South Spain), considering a landscape homogenization gradient. We further assessed the contribution of different frugivores to this function by mist-netting and scat collection. We differentiated two habitats within olive farms: olive grove matrix and seminatural woodland patches.

This work was funded by RECOVECOS project -Evaluating the Recovery debt of ecosystem services provided by the fauna in permanent croplands: effects of land use intensification and landscape complexity in olive groves- (Ref.: PID2019-108332GB-100, MICIN/AEI/10.13039/501100011033), LIFE Program project OLIVARES VIVOS (ref. LIFE14 NAT/ES/001094) and FEDER SUMHAL project Work Package 9. Task 9.3.2. Model impact of land use change -Sustainability for Mediterraean Hotspots in Andalusia- integrating LifeWatch ERIC (LifeWatch ERIC – FEDER, POPE 2014-2020; Ministerio de Ciencia e Innovación, Spain), CSIC is acknowledged for supporting Open Access publication.

'summary_seed_dispersers.csv' file has information of the species of frugivorous birds that have been detected dispersing seeds in the olive grove per each farm. 'summary_mobilised_seed.csv' file has information of fleshy fruit seed species that have been detected dispersed in the olive groves per each farms 'farm_information.csv' records information about each farm like location (coordinates), ground herb management, Seminatural woodland cover in the landscape and farm size 'metadata' records information about the meaning of columns in 'summary_seed_dispersers.csv','summary_mobilised_seed.csv' and 'farm_information.csv' files

Peer reviewed