Caladenia valida, is an endangered orchid species that has been recorded at four localities across Victoria and extending into South Australia.

All colonies have seen a decline over recent years. So far 47 orchid species have been recorded on Raymond Island of which there is only one spider orchid species, C. valida.
To date 17 Caladenia valida sites for Raymond Island have been located. The habitat of the sites vary having understorey plants including Acacia mearnsii late black wattle, Banksia serrata saw banksia, Banksia integrifolia coast banksia, Pteridium esculentum bracken, with a groundcover of Lomandra longifolia spiny-headed mat-rush, Imperata cylindrica blady grass, poa sp tussock-grass., Themeda triandra kangaroo grass, Danthonia caespitosa wallaby grass and unidentified grasses.

The earliest record of a spider orchid on Raymond Island that I am aware of, is in an article by Mrs Edith Bishop (nee Haylock) who attended the Raymond Island State School from 1923-32. and is quoted in M. Beesley’s Raymond Island School booklet; ‘Miss Greenwood would take us for walks on Friday afternoons in spring-time looking for wildflowers. We often found spider orchids, greenhoods, native correa and bearded heath’.

In 1990 over 500 plants (300 in flower and 200 in bud) were observed at the main site and have since declined in numbers even to as low as 18 in the 1997 drought and recovering to 50 in 2000 and 87 plants in 2002 from 161 recorded at Site.1.

In 2000 the BDFNC commenced a monitoring program at Site.1 by pegging each of the plants and numbering them. This has continued for the last three years with once a fortnight monitoring & recording for 2000 and 2002, and once a week during 2001.

The main threat to the orchid population is from browsing by local fauna including wallabies, kangaroos, wombats and rabbits. 62% of the plants observed in 2000 were browsed off destroying any chance of pollination and 83% in 2001. Damage by persons, vehicles, wind, insects and trampling by fauna was minimal despite the open areas.
Therefore, to maximise the potential for recovery of the orchid by natural means, a decision was made to erect a suitable fence around the orchid site to exclude the majority of browsing fauna.

In 2001 a grant application was made to Parks Vic to erect a suitable fence and the BDFNC was successful in receiving $1,490. As the area to be fenced was changed to include more plants further funding was sought and the DNRE provided a further $5,000 toward the project. A donation of $500 was made to the project by the Raymond Island Advancement League and the balance of $850 through BDFNC. In addition, a total of 195 hours was provided by BDFNC and the Raymond Island Community in the design and construction of the exclusion fence.

As part of the site is located on private property, consultation was made with the owner and an agreement signed providing a 2 year period to assess the effectiveness of the fauna exclusion fence and to improve the site to increase the potential recovery of the orchid.

During the 2001 spring, the BDFNC in conjunction with Raymond Island Landcare Group and local contractors, a 1.8m high fence was erected around the site of 1Ha encompassing a total of 139 C. valida plants within the site and 22 outside in the road reserve.

The fence was completed in time to monitor the exclusion of browsing fauna however we were unfortunate to encounter another year of dry conditions leading to drought.
Good autumn and winter rains promoted growth of plants in July but by August, the dry conditions prevailed reducing further promotion and eventually the majority of the colony wilted. 87 Plants were recorded with 74 wilting (85%). However, all was not lost! A few hardy plants, 4 in total, were able to complete their growth cycle - flower, pollinate (by small wasp), produce and disperse seed.

As for the effectiveness of the fence, only 1 plant was browsed in the Flora Protection Site (1% of the 87 recorded plants) and 5 plants out of the 13 recorded outside the fence (39%).

Andrew Bould