A water point design to facilitate seed dispersal into revegetation or pasture sites

Amanda N. D. Freeman

Introduction. Although perches have been shown to enhance seed dispersal into revegetation sites, the efficacy of providing a water source to attract seed dispersers is largely untested.  In a Griffith University-led study aimed at “kick-starting” conversion of pasture to forest www.wettropics.gov.au/cfoc , bird-attracting structures that included a perch and water trough at the base were shown to enhance frugivore-assisted seed dispersal.  A complementary study in the same sites has identified the seeds of over 40 bird dispersed species deposited in the water troughs (Amanda Freeman; The School for Field Studies, Centre for Rainforest Studies (SFS-CRS) and Griffith University; 2012-2014, unpublished data).  Although the water troughs demonstrably attracted frugivorous birds, most notably Pied Currawongs (Strepera graculina ) using the water to regurgitate, any seeds regurgitated into troughs would be unavailable to germinate (Fig 1.).

Preliminary trial. Using a commercially available automatic waterer used for poultry, we designed a water point with a water dispenser that is too small for birds to regurgitate or defecate into, allowing expelled seed to fall to the ground.  The device is also simple and relatively cheap to build (<$100 Australian).  Once installed, the device requires little attention because the water remains cool and evaporation is minimal so the water may last several months without replenishing. The waterer, a plastic container which distributes water to a small dish by the action of a float, sits on a sturdy metal base 1.5m high.  The base has a perch allowing birds of different sizes to access the water from several angles and an attachment for a camera to enable bird visits to be monitored.  We envisage that the water point may facilitate seed dispersal by attracting frugivorous birds that will regurgitate and/or defecate at or near the water point.

We conducted an initial trial at a revegetation site at SFS-CRS in February 2016.  For this trial we baited the water point with Kiwi Fruit (Actinidia sp.) but this was soon consumed by insects. During the trial we recorded two species of fruit-dispersing bird, Pied Currawong and Lewin’s Honeyeater (Meliphaga lewinii) using our prototype water point within one month of its installation in (Fig 2.).

Design of second trial. In July 2016 we established a small trial at SFS-CRS to test the relative efficacy of perches alone versus perches coupled with our water point device in facilitating seed dispersal into cleared sites that lack remnant or planted trees.  We have nine fenced 3m² plots in ungrazed former pasture, 15m from the edge of primary rainforest (Fig 3.).  Six plots have a perch, 3-4m high, cut to standard form from Sarsaparilla (Alphitonia petriei) trees.  Three of these plots also have a water point placed close to the base of the perch and a camera monitoring visits to the water.  Three plots have no structures.

Grass in all plots will be suppressed by herbicide spray (on an ‘as needed’ basis) and seedling recruitment in the plots will be monitored. In the first three months, no birds have been recorded using the water points in the trial plots.

Contact: Amanda Freeman, Centre Director, The School for Field Studies, Centre for Rainforest Studies, PO Box 141, Yungaburra, QLD 4884, Tel: +61 (7) 40953656; Email:  afreeman@fieldstudies.org