The City Nature Challenge has been running since 2016 when it was started as a competition between Los Angeles and San Francisco to record urban biodiversity using the iNaturalist platform. During a 7-day period, over 20,000 observations were made of 2500 species by over 1,000 participants. In 2017 the number of cities involved grew to 16, in 2018 it grew to 68 cities from various countries. In 2019 a full 159 cities participated and then 244 cities in 2020. Last year 419 cities participated from 44 countries, producing 1.27 million observations from 52,000 participants.
Greater Adelaide will again be participating in the City Nature Challenge 2022. The challenge will run for 4 days from Friday April 29th through to Monday May 2nd inclusive. Any observation taken during this time that is recorded within Greater Adelaide will be included in the challenge results. Following this, from May 3rd through to May 8th is the identification period. This time is provided to allow participants to identify as many species as possible from the 4 day challenge period. The challenge is to see which cities can make the most observations, record the most species and engage the most people. Results will be published on May 9th.
The whole of the Greater Adelaide region is included in the challenge. This area (following local government area boundaries) extends from the Murray River mouth, across Lake Alexandrina, up the river, around Murray Bridge, across toward Mount Torrens, up past Kapunda, across to the north of Thompson Beach and along the coast back to the Murray River mouth.
April has been the challenge month since the City Nature Challenge began as this coincides with the Northern Hemisphere Spring. Unfortunately for us this means the challenge will occur in Autumn and we will miss out of recording the tremendous emergence of life in our Spring. (For that, hold on for the Great Southern BioBlitz 2022). However this shouldn’t dissuade us, as in many years it is a Southern Hemisphere city that produces the most observations, species and participants.
Exactly how many species can be found in a typical suburban backyard?
Consider your yard, and have a guess how many species you might be able to find in it. Don’t count any cultivated or captive species. Obviously yards will range from courtyard to acreage, so your estimates will differ. Unless you are someone who regularly looks for life in their yard, your estimate could be out by a factor of 5 to 10. For a more detailed consideration, check out the post How Many Species?. Below you can find some tips of how to locate these often elusive species on your property.
The Size of Life Obviously the larger an organism the greater area of land is required to sustain a population of that species. You’re unlikely to find a Kangaroo in your yard unless there is a large natural area nearby. While you will encounter a few Vertebrate species in your yard, predominantly Birds with a few Reptiles and Amphibians, the majority of species are going to be small Invertebrates. So be prepared to look closely.
How Much Life This will all come down to Plants. The more you have in your yard (and surrounding area), the more species you will find. They draw in the herbivorous Invertebrates to chew the leaves, suck the sap, drink the nectar, and eat the fruit and seeds. These in turn attract the predatory Invertebrates and both will attract the insectivorous Vertebrates. The Plant litter feeds the ground and soil dwelling Invertebrates and encourages a diverse range of Fungi, whose fruiting bodies are consumed by various Invertebrates.
Time of Year Not all species that can be found in your yard will be present at the same time. Many species of Insects have flight times in the warmer months. Some are only present in their adult forms for one month of the year. Some species are active at different times of the day and during the night. Some will only ever visit your yard if there is a food source available, i.e. flowering or fruiting Plants. To get a full count of species in your backyard, you’ll need to be on the lookout throughout the year.
Time of Day Different creatures are active different times of the day. If you investigate your yard at the same time on each day, you’ll only see a subset of what is actually there. Try to look around your yard at various times of the day, and after sunset. Turn on some outdoor lighting in the evening and see what is attracted. Keep an eye on birdbaths and any flowering Plants as these will have visiting Birds throughout the day, with some perhaps only visiting once per day. Take a powerful flashlight out after dark and search for nocturnal creatures. Don’t forget the many nocturnal Invertebrates. Keep an eye out for the Grey-headed Flying-Foxes (Pteropus poliocephalus). These head out from the colony in Adelaide each evening. Each year in April/May I find them feeding in a local Palm around 22km from the colony, often around 10pm.
Weather Not only will inclement weather keep us inside, it will do the same for many creatures. Many Insects will be most active in the calmer and warmer parts of the day, however they can also be harder to photograph when most active. If the weather is poor, try again another time. The difference the weather can make can be dramatic.
Resident, Visitor or Fly-By Species seen in your yard fall into a few categories. ‘Residents’ that have their homes in your yard and spend most of their time there, ‘Visitors’ with homes elsewhere that come to your yard for food and other resources, and ‘Fly-By’ species that are passing through the physical space of your yard, but are not specifically interested in it. The number of Resident species will be determined by the size of your property and the available resources on it. The number of Visitors is dependent on the resources present in your yard and the homes available in the area surrounding your property. Fly-Bys are mostly chance encounters, but are higher when local surroundings are more diverse.
Surrounding Landscape Most of the species observed in our yards won’t be residents. They will be passing through, visiting and feeding. So the environment surrounding your property will have a large impact on the number of species you observe. If you have nearby natural areas and abundant food sources in your yard, you will get many visiting species. Newer suburbs with smaller backyards and less established vegetation will see less overall species.
Evidence of Organism Sometimes you might be able to find evidence of a species. Consider recording Frogs and Birds if you can hear them but can’t locate them, or if they are too far away for your camera. You can also look for other signs, such as Bird feathers.
Finding Organisms – Observing It is not difficult to find Rainbow Lorikeets in your yard. In fact it is hard to miss them. However keep an eye on established trees and shrubs, particularly if they are flowering, and you may spot some quieter species of Bird that have gone unnoticed. If the flowers are closer to the ground, keep an eye on them for visiting Insects. The longer you observe, the more species you’ll likely spot. If you have a birdbath, keep an eye on it throughout the day. Some Birds may visit briefly only once every day or so.
Smaller creatures including Invertebrates tend to be rather more elusive. Evolved to avoid predation, they also avoid being seen by us as well. To find them you’ll need to move slowly and look closely. Many Insects are at least partially camouflaged and are easily missed unless looking with intent. Some can see a surprising distance, will see us coming and hide on the underside of a leaf. Some species of Beetle will release their grip and drop to the ground if disturbed, often just as you get the camera in focus to take a shot. A quick method of finding Invertebrates in Plants is to place a sheet below a tree or shrub, shake the branches and record what falls out.
Finding Organisms – Searching If you have rocks or logs in the yard, don’t forget to look under them. Have your camera ready as many species will try to hide when disturbed. Avoid lifting anything with your hands as Snakes/Spiders/Scorpions aren’t going to be happy having their homes disturbed. Return the rocks and logs to their original positions when finished.
If you have a pond, have you considered what might be living in it, aside from Mosquito wrigglers? Sweep a fine mesh net through the water or collect some pond water in a jar and see what aquatic Invertebrates you can find.
Many Invertebrates can be found in leaf litter and soil. Consider collecting leaf litter and sifting through it on a white sheet to see what falls out. Soil can be dug from the ground to a spade depth and dropped into a bucket of water, where the Invertebrates will float to the surface and can be collected.
Finding Organisms – Attracting Offering food sources can draw out resident species and attract additional visitors to your yard. Suitable vegetation can ensure food is available year round. A birdbath or seed dish will attract a range of Birds, but will work best if established so its availability is known to local Birds. Add a few large stones to the birdbath to give flying Insects a surface to land on before taking a drink.
Different Invertebrate species can be attracted using various substances from our fridges and cupboards. Try placing a range of substances in jar lids or bottle caps at locations around your yard, ideally in sheltered locations out of the rain. It may take a few hours or few days to be found. Leave them out for the four challenge days and move them around the yard. Keep them away from the house to avoid attracting pests. Sticky substances can also be applied to tree trunks and branches. Ant species will find sugary foods (i.e. honey, jam, sugar water) and fatty foods (i.e. bacon pieces, cheese, peanut butter). Other substances that can attract various Beetles, Flies, Moths and Plant Bugs include terpenes, alcohol and methanol, fermented fruits and rotting meat.
Finding Organisms – Attracting: Moths Turning on some outdoor lighting, and setting up a white sheet will attract some species. The greatest number of species will be attracted with a bright UV light source and a white sheet hung nearby. However any outdoor lighting will attract some species and the sheet can be placed on a flat surface. i.e. table below the lighting if there is no option to hang the sheet. Consider temporarily replacing an outdoor light with a UV Blacklight. This will increase the number of species attracted significantly. The light will not only attract Moths, but also some Beetles, winged Ants, Katydids, Lacewings and various other taxa. You may also get some visiting predators such as Mantises attracted by the abundant food. Many more species will be out if the evening is warm and calm.
The visitors can be photographed in place. Many Moth species can be IDed to species with a top down photo, but some may need profile and underside views. Don’t forget the many smaller species 5mm long or less. With the camera as close as possible the flash may only illuminate one side of the specimen, so consider using a torch to light up the opposing side. This additional light will help to increase the shutter speed to ensure your photo is clear.
Finding Organisms – Temporary Homes Cardboard or metal sheets can be placed on the ground around your yard. Place some in cool and damp protected areas, some in exposed sunny areas. Various Invertebrate species will seek shelter under these and if lucky they will attract predators, in particular Lizard species. The sheets in cool damp areas may attract Frogs. The longer they are left in place, the more established the homes become.
Finding Organisms – Traps There are many simple methods for trapping Invertebrates with varying degrees of success. A Pitfall Trap is a container or jar buried flush with the surface of the soil that Invertebrates crawl into but cannot get out. A simple Funnel Trap and Side-Door Trap can be made from empty soft drink bottles (See Traps section HERE for construction details).
Collecting & Photographing Specimens can be photographed in situ, but this doesn’t always allow for photos sufficiently clear or from the necessary angles for identification purposes. Consider having available a container to temporarily detain any Invertebrates found. These specimens can then be photographed on a white sheet or similar in more controlled lighting. For the more active specimens, place the container in the fridge for a while to slow them down. They will recover quickly as they warm up and can then be released after suitable photos have been taken.
How many species? Try each of the tips above to see how many species you can discover on your property. See a full list of the more than 580 species I have found on mine in my Backyard Species List.
How many species would you expect can be found it a typical suburban backyard? Maybe 50? Or perhaps 100? More? The question is a little vague, so lets try to narrow it down.
There are going to be quite a few factors that affect exactly how many species you are likely to find on a suburban property.
Let’s start with property size. How large is a typical suburban property? Let’s consider the lower end to be multi-story townhouse on 150m2. At the upper end an older style property with perhaps 2,000m2.
We must consider how much of this property is utilised for human needs, i.e. house, patio, driveway, garage, pool, paved areas, etc. These areas typically exclude the majority of species. A townhouse property is likely to be 80% utilised, leaving approximately 30m2 ‘undeveloped’. An older style property may only utilise 10% of the land, leaving up to 1,800m2. The difference between these two will have a significant effect on the number of species likely to be present.
Now consider the form of that ‘undeveloped’ land. Is it a heavily manicured garden consisting of a large patch of lawn with interspersed garden beds filled with exotic plants, a vegie patch and some fruit trees. To our eyes, such a garden may seem to be filled with life. The Honey Bees always pollinating, the vegie patch constantly under attack by various Invertebrate herbivores, the Birds flitting about the trees. But our eyes alone are a poor judge of biodiversity. So much goes unnoticed, either too small to be spotted, camouflaged, or occurring after dark or out of sight.
Or is the garden in a more natural state with some of the original native trees and shrubs. Or some planted local native species. Or even a small patch of degraded remnant vegetation. So many species are critically dependent on specific vegetation and environmental conditions that even a few planted local species can dramatically alter the number of species in the yard.
How ‘structured’ or ‘ordered’ are the garden areas. Does the garden consist of only a few species, perhaps arranged into neat repeating rows. Our attraction to patterns and geometric forms may result in a garden we find appealing, however this doesn’t necessarily correlate with biodiversity. Even where this setup uses native vegetation, the arrangement and limited number of species is likely going to limit the utility for native species.
Are the fallen leaves swept up. Lawns raked. Plants pruned. How about removal of debris like fallen branches, logs and rocks from the yard. While these maintenance activates are considered desirable to keep the garden orderly, these materials are frequently used by native species for food, shelter, nesting material, etc. Removing them also removes the dependent species.
Does the garden consist of one large area, or is it broken up into separate sections. Front yard, backyard, driveway border. Are these areas separated by inhospitable environments. A simple paved garden path isn’t going to deter the Birds in your yard, but to ground dwelling Invertebrates it may represent an impassable barrier. Or at least, a barrier than significantly increases risk.
Do the plants in the garden sprout, grow, mature and seed quickly. How dynamic is the garden. How much maintenance does the garden ‘need’. A slow growing, static garden has limited resources available for species to utilise. The plants are the source of chemical potential energy that animal life requires, and are there to be consumed. More plant growth results in more food to be consumed and a greater number and variety of species present.
A property doesn’t exist in isolation. Many of the species found are likely to reside elsewhere and only visit the garden. As such, the surrounding environment is going to have a significant effect on what type and how many species found. Is the property part of a new housing development where all the local land was recently cleared. Does the property back onto an area of native vegetation, or a creek.
Obviously the local climate is going to be a significant factor in the number of species found. Semi-arid, Mediterranean, wet forest. The more warmth and water, the greater the biodiversity.
How much ‘work’ is put into the garden. In this instance we are considering ‘work’ to be the additional time, energy and resources used to maintain the garden in a state suitable for maximising biodiversity. This may take the form of extra watering in dry weather and feeding the soil with additional nutrients. In urban cultivated environments plants don’t often seed and produce seedlings, or if they do the location isn’t suitable. Extra work is required to replant new seedlings each season. Additional work put into the garden can boost the biodiversity significantly. Such a garden has the potential to maintain biodiversity exceeding that of natural areas.
Exactly what scale of life is considered will also determine the total number of species found. The ability to see and identify the species is key. While a spade full of soil may contain hundred of species of bacteria, these are somewhat beyond identification without dedicated equipment and specialist knowledge. However, they are still present and should be considered as part of the biodiversity.
These 11 factors all come into play when trying to determine how many species you could potentially find on your property. However, not all factors are equal. Some will have a dramatic effect and others may be less critical. The local climate and type of surroundings are likely to be the most significant and unfortunately there often isn’t much that can be done to change these. The size of the property is important, but it’s not something easily changed. To aid in increasing biodiversity within your yard, the best option is to aim for a natural, unstructured, debris filled, connected and dynamic garden.
Now to consider the actual number of species. I have been casually recording species I have located on my property for the past three years. You can see on the chart below how my property aligns with each of the 11 factors. I continue to find new species every week with minimal effort. I have still yet to do thorough investigations of the leaflitter and soil. As of Feb 2022, I have recorded at least 582 species, and uploaded them into my Backyard Biodiversity project on the iNaturalist platform.
These 582 species include 212 Moths, 77 Beetles, 50 Flies, 43 Wasps, 35 Bugs, 32 Spiders, 28 Birds, 20 Introduced weeds, 13 Ants, 8 Butterflies, 8 Cockroaches, 7 Hoppers, 7 Fungi, and many more taxa. This list excludes the 100+ species of cultivated Plants. The full list is presented here. There are still quite a few species I’ve recorded but have yet to identify that will boost this total further. While the rate of additional species discovery has slowed significantly, I expect that 800 to 1000 species is a reasonable estimate for the total number of species to be found.
So consider your property with regard to the 11 factors above, and make an estimate as to how many species are utilising it for food and shelter. Think twice before sweeping, raking, pruning or otherwise altering the garden. Then get out there and start discovering. Don’t forget to upload your sightings to iNaturalist to keep track.
Context: Constructed in 2013 by the City of Onkaparinga as part of stage 2 of it’s Water Proofing the South initiative, this now established wetland consists of 9 ponds, surrounded by gravel paths with several bridges. The area has been fully revegetated.
A walk shortly after sunrise looping around most of the wetland ponds. This time of year the water level is low in most of the ponds with Pond H completely dry as usual.
An single Threskiornis molucca (Australian White Ibis) walked the bank of Pond I pushing its beak deep into the soft mud. Quite a few small groups of Ocyphaps lophotes (Crested Pigeon) dotted around the tracks. No sign of any Pacific Black Ducks, many of which at this location are hybrids with feral Mallards. A very quiet location at this early hour.
This January saw 8,720 observations covering 1,955 species from a total of 507 observers. There were 94 species receiving their first iNat record in SA. This month there were 103 new observers contributing their first observations in SA. Upon this months observations, 631 identifiers contributed a total of 15,385 identifications.
Uploads for SA at the end of January stand at 289,846 observations of 8,706 species from 4,124 observers with, as of today, 4,688 identifiers providing 527,932 identifications.
The international National Park City Foundation has awarded Adelaide National Park City status, making Adelaide the first in Australia and second in the world.
Featured Observations from January A Gasteruption Wasp with it distinctive ovipositor searching for Bee/Wasp nests by @toboote. A Blue-billed Duck commonly sighted at Laratinga Wetland by @darcywhittaker. A Grey Shrikethrush with a juicy meal in Para Wirra CP by @anthonypaul. A Badge Huntsman moulting by @bryanhaywood.
See the full list of the popular observations from January here.
(These are taken from observation during the month with at least one ‘favourite’. If you see an interesting observation from SA, remember to favourite it, and it might appear here at the end of the month).
Featured Project The previously named Aldinga Scrub Conservation Park has been expanded to include the Aldinga Washpool area just to the south, taking on the new name Aldinga Conservation Park. The iNat project has over 4,000 observations of 500 species from over 100 observers. If you visit, you’re almost guaranteed to see many Western Grey Kangaroos and Superb Fairywrens in the scrub, and numerous bird species at the ephemeral Washpool. (Binoculars or camera with long lens recommended at the Washpool)