Backyard Biodiversity: 400 Species and Counting


Background
Beginning in May 2018, encounters with species on the property have been recorded, uploaded to iNat and added to a Backyard Biodiversity project. Early on, these were simply intended as additional iNat observations. Most were chance encounters. The question arose as to how many species could actually be found in a typical suburban property. Early, and admittedly ignorant, estimates were that 100 or so species were likely to be found (excluding cultivated Plants).


The first 12 months tallied only 47 species. Mostly Birds, Spiders, a few Moths and Butterflies, Flies and Beetles. Each month a few additional species were added to 90 species by Nov '19.


At this point a more active approach was taken and a UV light was used periodically at night. (Actually a 40w Black Light Fluoro Tube). In the first month this added 75 new species. Then another 59 the following month, and 33 the next. This coincided with the warm summer evenings and by April '20 the total species count had jumped to 343. The added species consisted of approximately 140 Moths, 35 Beetles, 23 Flies, 17 Bugs, 16 Wasps, 14 Spiders, 12 Ants (mostly alates), and a few from other groups.


The count has continued to tick over and as of Oct '20 sits at just over 400 species (according to the project count) from over 1,600 observations.



Current Status
To date the most represented taxa are by far the Moths with 162 species recorded, followed by Beetles at 45 species. Almost all of these have been recorded visiting the UV light after sunset.

37 species of Flies and 19 species of Wasps have been recorded with most collected on warm afternoons resting on the shade cloth walls of a patio that inadvertently functions as a large trap.

25 Bird species have been recorded. The introduced European Blackbirds and Spotted Doves live in and around the property. Local native regulars are the New Holland Honeyeaters, Silvereyes and Red Wattlebirds. Rainbow Lorikeets and Crimson Rosellas are common but tend to stay high in the trees. Seasonal visitors include Eastern Spinebills associated with specific flowering plants, Magpie-larks and Willie Wagtails. The locally endangered Yellow-tailed Black Cockatoos arrive seasonally in large flocks to eat the seed from large numbers of planted Aleppo Pines. An Accipiter species has a nest nearby and breeds each year. These have been IDed as Brown Goshawks and as Collared Sparrowhawks going to show IDing these is difficult. The local Raven species (likely Little Ravens) have taken to using the birdbath to soften and break apart food, which appears to be mostly bread rolls likely collected form nearby commercial areas.

Rarer and unexpected species include a Koala in a neighbouring tree, Grey-headed Flying-Foxes feeding on fruiting Palms, Small Dingy Swallowtails breeding on a Citrus tree, Laughing Kookaburras, a Tea-tree Longhorn and an undescribed Stiletto Fly.



Analysis
The species recorded here represent not only those living on the property, but predominantly species that are visiting or passing through. For some species it can be easy to differentiate between resident and visitor. But for flying Insects it is often impossible to determine. As such the number of species recorded is only partially a function of the property, and is heavily dependent on the surrounding environment. This applies not only to the number of species, but also which taxa are present.

Given that many recorded species are not residents on the property, in order to be recorded they still need to be visiting the property. This implies a suitable enticement must be present. Were the property to consist of 750m2 of concrete, the species recorded would drop almost to zero. Add a tree in the centre and various leaf eating and sap sucking Insects move in, followed by invertebrate predators and Bird species. Remove the concrete and replace with leaf litter and the ground dwelling species appear, seeds from Plant species blow in and sprout, providing further enticement for other Animal species. It's clear that the form of the property is a critical factor in the number and mix of species recorded.


Expansion
Recognising that around half the species recorded so far have been enticed to visit the property through the use of a UV light, a plan has been established to increase the species recorded through a more natural method. Namely, establishing a highly diverse range of local Plant species (from across the Greater Adelaide region) with the specific intent of maximising invertebrate biodiversity. This will be reinforced by informed use of materials to create artificial 'homes' for various taxa.

The intent here is not to 'restore' the environment. Given the suburban location, subject to constant and sudden changes, restoring a small area to a more natural state would provide little benefit. Instead the area will be artificially maintained at a higher level of biodiversity through regular and sustained human intervention.

Given the limited natural areas remaining in the suburban environment, and that those remaining frequently contain only a small selection of the Plant and Animal species they once did, the hope is this artificially biodiverse area will provide somewhat of an oasis. Not specifically for the larger fauna, but for all those small invertebrate species that are essentially unknown to the general populace and which get little consideration in such manmade environments.

Time will tell whether such changes have any measurable effect. Establishment is progressing with much of the plants expected to be sufficiently grown by Spring 2021. Observations will continue to be uploaded to iNat hopefully revealing an increase in species diversity at time progresses.

The current target is 500 species by the end of this year.


Still "Needs ID"
The current number species observed may in fact be higher, with many invertebrates having been only identified to Family or Genus, with some stuck at Order. If you have any expertise in the following areas, your assistance with IDs in the following groups would be appreciated. Many of the observations have macro-level photos from multiple angles.

Needing ID:
Moths
Spiders
Plants
Ants
Flies
Beetles
Wasps
Bugs
Everything Else

If you're interested in discovering what can be found on your own property, check out this "Backyard Biodiversity" guide.

Posted by cobaltducks cobaltducks, November 07, 2020 07:59

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