Second trial of watering device design to facilitate seed dispersal into revegetation sites

Amanda Freeman

Figure 1. Watering device on stand with camera above.

Introduction. This summary reports on methods and results of a trial to improve the design of a watering device. (See preliminary trial in EMR summary). This trial drew upon lessons learned In the “Kickstart” pasture conversion project,  (see https://authors.elsevier.com/a/1bhz81L%7EGwOHhQ) where perches and water basins were installed on two private properties in the upper Barron, Queensland, with the aim of catalysing rainforest regeneration.  The seeds of 31 species of bird-dispersed forest trees and shrubs were deposited in water basins, largely due to Pied Currawong (Strepera graculina) using the water to regurgitate seeds. The Kickstart Project demonstrated that there is potential for supplementary water to enhance seed dispersal into revegetation sites; however, the seeds regurgitated into basins in that study were not deposited in sites suitable for germination, limiting the basins’ usefulness as restoration tools.

Our 2016 EMR Project Summary described a watering device designed to overcome this problem of seed being deposited in water receptacles.  The trial was conducted at the School for Field Studies property near Yungaburra, Queensland and this summary reports the results of our trial which aimed to identify whether frugivorous birds would use our watering device. We also assessed the amount of maintenance the watering device required to function effectively.

Figure 2. A Lewin’s Honeyeater (Meliphaga lewinii) at a watering device, May 2017.

Watering Device Trial. In July 2016, three 3 x 3m plots were established in an approximately 120 x 30m area of disused pasture at the School for Field Studies property. The site was located 15m from the edge of primary rainforest on one side and adjacent to a mosaic of scattered trees, restoration plantings and secondary forest on the other three sides. Each plot had a perch, 3-4m high, cut to standard form from Sarsaparilla (Alphitonia petriei) trees. Each plot also had a watering device placed close to the base of the perch. These were commercially available automatic water dispensers used for poultry set on a 1.5m high base with a perch that allowed birds of different sizes to access water from several angles and for expelled seed to fall to the ground (Figs. 1-3).

Motion-activated cameras (Ranger Compact 2 MP) were installed above each watering device to monitor visits to the water. Apart from a total of 37 days when the cameras were removed for maintenance, the three watering devices were monitored from 22 July 2016 to 13 December 2018 when the trial ended. In the analysis, continuous series of images of one or two birds at a watering device were treated as one visit by that species.

The three plots with a perch and watering device were interspersed with plots that only had a perch or had no structures at all. Apart from within the plots and a narrow access track between them, grass and woody vegetation were not controlled in the surrounding disused pasture.

Figure 3. A Victoria’s Riflebird (Ptiloris victoriae) at a watering device, October 2016.

What we found. Eighty-six visits by three frugivorous bird species were recorded across the three watering devices over the course of the trial. Ninety percent of visits were during the late dry seasons (September-November). One watering device was visited much more often than the others, receiving 70% of all visits. The other two watering devices received 20% and 10% of visits respectively (Table 1).

One bird species, the generalist Lewin’s Honeyeater (Meliphaga lewinii), was by far the most frequent visitor to the watering devices, making up 80% of frugivore visits (Fig. 2). Victoria’s Riflebird (Ptiloris victoriae) was the next most frequent visitor (14% of visits, Fig. 3) and Little Shrikethrush (Colluricincla megarhyncha) was the least frequent visitor (6% of frugivore visits). The only other species that used the watering devices was the Olive-backed Sunbird (Nectarinia jugularis) for which five visits were recorded. All species were recorded drinking from the watering devices. Only the Olive-backed Sunbird could bathe in the small water outlets and were recorded doing so on three occasions.

The watering devices required little maintenance over the 2.5yrs they were deployed. Water was replenished when needed at roughly six-monthly intervals and the water outlets, which collected debris and algae, were cleaned monthly. The devices had no noticeable deterioration at the end of the study.

Table 1. Number of frugivorous bird visits to three watering devices in disused pasture, 22 July 2016 to 13 December 2018.

Conclusions. Our watering devices were only used by three frugivorous bird species, most frequently by the Lewin’s Honeyeater a dietary generalist. Generalist avian frugivores tend to move mainly in more open habitats enhancing the dispersal of pioneer or non-forest trees across the landscape rather than carrying seeds from remnant forest into pasture.

Bird use of the watering devices was highly variable and largely confined to the late dry season when rainfall is low, and temperatures are warm to hot. These are poor conditions for germination and plant growth and likely limit recruitment of dispersed seeds.

Despite these limitations, watering devices are a low-cost intervention that may augment perches and attract frugivorous birds, thereby accelerating forest regeneration. The watering devices deployed in this trial did not collect seed, preserving the potential for seed to be dispersed. They required little maintenance and proved suitable for prolonged outdoor use. Watering devices warrant further investigation. 

Acknowledgements. Thanks to William (Bill) Johnson and John Hall for designing the watering device stand and camera attachment and preparing and maintaining the plots. The School for Field Studies funded the trial.

Contact. Amanda N. D. Freeman. Nature North, PO Box 1536, Atherton, Qld, 4883 Australia. The School for Field Studies, Centre for Rainforest Studies (PO Box 141, Yungaburra, Qld 4884 Australia; Tel: +61 (0) 438 966 773; Email: amandafreeman@naturenorth.com.au).

See also EMR project summary on the preliminary trial of this project: https://site.emrprojectsummaries.org/2016/11/02/a-water-point-design-to-facilitate-seed-dispersal-into-revegetation-or-pasture-sites/