Bendigo Field Naturalists Club - nest box project
For the last 30 years (c. 1986-2016) the Bendigo Field Naturalists Club has been placing nest boxes throughout the bushland parks and reserves surrounding the City of Greater Bendigo. Nest boxes that target the Brush-tailed Phascogale have been installed to restore hollow availability in forest areas where past disturbance has caused coppice regrowth of small multi-stemmed trees that lack natural hollows. Boxes have been maintained and monitored by the club over this period.
2015-2016 Nest Box Survey
In 2015-2016 the Bendigo FNC undertook an audit of nest boxes placed in the forest since the 1990s (Figure 1).
Figure 1 Bendigo FNC 2015-16 survey area.
The audit and survey was undertaken to better understand the relevance of nest boxes for phascogale conservation in local forests and more generally their use by other hollow dependent species.
The audit aimed to establish how many of the previously installed nest boxes were still in place, their physical condition and repair needs, evidence of use by different species, and to collect baseline data to assist in future management and best practice decisions for land managers and stakeholders.
Some of the findings from nest box audit:
- Of the 332 sites where a nest box had been placed 19% of boxes were either missing or beyond repair. Of the boxes still on trees 27% needed some form of repair such as reattachment, replacing/repairing lids and/or patching chewed holes.
- Approximately 16% of boxes had the entrances chewed to beyond the preferred phascogale entrance hole size of 45 mm diameter and this allowed other species to use the boxes.
- Hanging nest boxes directly from a nail through a hole drilled into the back of the box was the most reliable method of attachment. Boxes nailed to a tree using a batten were found to have more often come loose.
- Lids and metal hinges were found to be weak spots and were frequently found loose or damaged.
- Boxes used by phascogales over consecutive seasons became full of compacted nesting material that hardened and filled the box. The decreasing volume of internal space was found to reduce their suitability for further use and highlights the need for ongoing regular maintenance (cleaning) of boxes after their placement.
- Of the 237 nest boxes inspected 8% were empty. Evidence of Brush-tailed Phascogale was found in 51% of the boxes inspected. (Figure 2)
Figure 2 Findings from 2015-16 Survey: Nest box usage by species in Bendigo Forests. Source: Bendigo FNC.
Current Nest Box Program 2017
The Bendigo Field Naturalists Club nest box management area currently covers approximately 1800 ha in the southern sections of the Greater Bendigo Regional Park and Greater Bendigo National Park (Fig 1). There are a total of 290 functioning artificial hollows in the club’s program with another 100 to be installed during 2018. The new boxes have been funded by the City of Greater Bendigo and will be constructed by Community Services. These will be installed in collaboration with Parks Vic and DELWP.
October 2017 Survey: Greater Bendigo Regional Park
The Bendigo FNC has closely monitored nest boxes in a 600 ha section of the Greater Bendigo Regional Park since the mid-nineties. Consistent evidence of female nesting activity has been recorded in this area.
In October 2017, 140 nest boxes were inspected (Fig 3). Of these 38 active nests with fresh scats and nesting material of feathers, stringy bark and wool were found with nine boxes being occupied by groups of juvenile phascogales. These results and long term monitoring demonstrate the area’s significance for phascogale conservation.
Figure 3 Inspection camera used by Bendigo FNC to undertake monitoring.
Nest box design, installation and management:
Box volumes currently in use range from 8 to 16 litres. Entrance holes are placed on the side of the box nearest to trunk so the animal is less exposed to predators when entering or leaving.
Boxes are hung from a 6-inch nail placed into the tree on a 45-degree angle. Larger diameter trees are selected when available so that the box receives greater thermal buffering from extremes of temperatures experienced in the Bendigo region. Protection from overhead canopy and shading from adjacent trees is carefully considered to provide maximum protection from solar radiation in summer. Best practice tip: install boxes at the time of day when this can be most directly assessed.
Height for placement on trees is between 3-4 metres for practicality. For best phascogale box placement a tree is selected that has branches or canopy that interconnect with adjacent trees. This allows phascogales to jump across when dispersing so the animal can avoid travelling on the ground in areas immediately surrounding the base of the tree with the box.
Where possible, at least two boxes are installed at each location. The distance between boxes is no more than 5m. This provides adequate boxes for phascogales and sugar gliders otherwise gliders may prevent phascogales from using a box where only one is available. Best case scenario would be to place a cluster of four boxes enabling both winter and summer shelter that caters for changing sun angles/direction during winter and summer seasons and the extremes of seasonal temperature experienced in Bendigo.
It is important to note that although nest boxes play an valuable role in providing shelter in areas where forests have been modified they are not as good as real tree hollows which provide superior thermal protection from heat and cold. A study by Rowland et al 2017 found nest-box temperatures were strongly influenced by ambient temperatures and solar radiation whereas tree hollows buffered external temperature fluctuations.
- Trials are in progress to determine temperature profiles in extreme temperatures >40C, <0C using various types of nest box materials and designs i.e. PVC pipe, foamed PVC boxes, wooden/ply boxes, natural log hollows.
- To make boxes less attractive to bees the addition of raw wool as a starter nesting material is being tested. This will reduce the internal volume of boxes, which has been identified as a potential factor limiting bee survival after invasion of boxes. By limiting the available space it is hoped that bees will avoid selecting boxes as new hive sites. Wool also has excellent insulation properties and will not compact, so may also address the issue of boxes becoming unsuitable when overfilled with old compacted nesting material.
- Investigation of materials with higher resistance to chewing and weathering is currently being trialled using a protective covering of bitumised metal damp coursing placed over the outside of box lids and hardwood templates over chewed entrances.
- Maurice Lewis talk to SWIFFT 2012 pdf.
- Rowland, Jessica & Briscoe, Natalie & A. Handasyde, Kathrine. (2017). Comparing the thermal suitability of nest-boxes and tree-hollows for the conservation-management of arboreal marsupials. Biological Conservation. 209. 341-348. 10.1016/j.biocon.2017.02.006. Abstract on ResearchGate.
- Bendigo Field Naturalists Club
- Brush-tailed Phascogale project - Friends of Brisbane Ranges