Celaenia excavata, the bird dropping spider of Australia and New Zealand, derives its name from mimicking bird droppings to avoid predators, mainly birds.Several groups of spiders have evolved an effective strategy against being eaten by day-active predators like birds and wasps – they have bodies that look like unappetising bird droppings.
Habitat and appearance
The males are much smaller than the females, about 2.5 mm as opposed to 12 mm. The females have up to 13 egg sacs, with about 200 eggs each, strung together with strong threads. Their toxicity is unknown, but may be able to cause mild illness in humans.
Celaenia excavata is found throughout large parts of eastern and southern Australia and have also been recorded in central Australia; they are also seen in suburban gardens.
The egg sacs of the bird-dropping spider are large, marbled brown coloured spheres, each about 12 mm in diameter and containing over 200 eggs. Up to 13 sacs are silked together in a group, beneath which the spider may be found awaiting prey.
- COMMON NAME ：Bird-dropping spider
- SCIENTIFIC NAME：Celaenia excavata
- TYPE：Arachnid
- DIET：Carnivorous, eating insects (mainly moths)
- AVERAGE LIFESPAN：One year
- SIZE：Between 12mm (female) and 2.5mm (male)
Bird-dropping spiders (Celaenia excavata) are found throughout eastern and southern Australia and have on rare occasions been sighted in central Australia and up near Uluru. The species is also found in New Zealand.
They’re common in suburban gardens, especially those with citrus or other types of orchards, but you’d be forgiven for missing them – their camouflage can work just as well on humans as it does on birds, their main predators.
While the males are absolutely tiny, with abdomens measuring only 2.5 mm long, the females grow to a sizeable 2 cm. These spiders are known for having a large, broad and triangular abdomen, which is decorated in splotches of white and brown, in a distinctly poop-like fashion.
The Bird Dropping Spider: A Master of Mimicry
The Bird Dropping Spider (Celaenia excavata) is a unique and fascinating spider species found in eastern and southern Australia.
Of the family Araneidae, they’re also sometimes called Death’s Head Spider, Orchard Spider, or the Bird-dung Spider.
You can sign up to our general or childcare first aid courses to learn more about identifying and treating spider bites. We have locations across all of Australia.
Table of Contents
Appearance
Habitat and Distribution
Behaviour
First Aid
Final Thoughts
Appearance
The Bird Dropping Spider, as the name suggests, has evolved to have a body that looks like bird droppings. The coloration and pattern on their abdomen resemble the texture and colour of bird droppings.
This clever disguise helps them blend in with their surroundings and avoid detection by predators such as birds and other insects.
They have a broad and triangular body that is brown or greyish in colour, and can have a diameter of 12 mm in females and 2.5 mm in males.
Despite their small size, the Bird Dropping Spider has strong front legs that allow them to capture prey. Their web is also incredibly strong and sticky, allowing them to catch and hold onto insects that are several times their size.
They prey on a variety of insects, including moths, flies, and beetles.
Habitat and Distribution
The Bird Dropping Spider is most commonly found in eastern and southern Australia, though they have been recorded in central Australia.
The Bird Dropping Spider is usually found hanging upside down from its web, which is typically constructed on the edge of a leaf or twig.
They prefer to live in areas with high humidity and lots of vegetation, such as rainforests and wet eucalyptus forests, but can also be found in urban areas such as parks, orchards, and suburban gardens.
These spiders are nocturnal and are most active at night, when they use their webs to catch their prey.
Habitat and appearance
The males are much smaller than the females, about 2.5 mm as opposed to 12 mm. The females have up to 13 egg sacs, with about 200 eggs each, strung together with strong threads. Their toxicity is unknown, but may be able to cause mild illness in humans.
Celaenia excavata is found throughout large parts of eastern and southern Australia and have also been recorded in central Australia; they are also seen in suburban gardens.
The egg sacs of the bird-dropping spider are large, marbled brown coloured spheres, each about 12 mm in diameter and containing over 200 eggs. Up to 13 sacs are silked together in a group, beneath which the spider may be found awaiting prey.
Hunting
Its diet consists almost exclusively of male moths, which it hunts at night by mimicking the scent of female moths.
The bird dropping spider stays motionless on its web during the day, only hunting for prey at night. It hangs down from a single silk thread and releases a pheromone which mimics the sex smells released by female moths. When a moth comes near, the spider will capture it with its powerful front legs.
Behaviour
One interesting aspect of the Bird Dropping Spider’s behaviour is the chemical mimicry it uses to attract prey.
The spiders release a chemical scent that mimics the pheromone released by female moths to attract male moths. This scent helps the spiders lure their prey, particularly male moths, into their webs.
Another interesting behaviour of the Bird Dropping Spider is their use of short silk threads to drop from their webs and escape from danger.
When threatened, the spider will drop down on a short silk thread, then climb back up when the danger has passed. This behaviour is particularly useful for avoiding predators such as birds and wasps.
Females can lay up to 200 eggs, which are stored in egg sacs measuring roughly 12 mm in diameter.
First Aid
The Bird Dropping Spider is not dangerous to humans.
Its venom is relatively mild and not lethal, although it can cause mild to moderate pain and swelling if you are bitten.
If you are bitten by a Bird Dropping Spider, you can apply a cold compress or ice to reduce pain and swelling. You can do this for periods of up to 20 minutes.
DO NOT use the Pressure Immobilisation Technique, as the venom moves slowly and this will just worsen the pain.
If symptoms become severe, or last longer than several hours, seek medical attention.
Final Thoughts
Bird Dropping Spiders are a fascinating species that have evolved to camouflage as bird droppings.
They are not dangerous to humans.
If you would like to learn more about providing first aid in the event of an insect bite or sting, book a First Aid course with us today. You can also learn how to provide first aid in an education and care setting.
Bird-dropping spider
The bird-dropping spider sounds like a creature better suited to a Halloween horror movie than your regular household backyard.
Although considered a large spider species, which is enough to make an arachnophobe tremble, the name of these interesting spiders is far more literal, coming from their ability to mimic a bird’s poo, or ‘droppings’.
Found throughout much of eastern and southern Australia, with rare sightings in central Australia and near Uluru, the bird-dropping spider (Celaenia excavata) also considers New Zealand its home.
Additionally known as the death’s head spider (thanks to its skull-like markings) and the orchard spider (as it hunts for moths on fruit trees), the bird-dropping spider’s large size, unusual colour patterns and resting posture make this orb-weaver hard to forget.
With venom that isn’t considered toxic to humans, these spiders make their homes within many suburban backyards, although actually spotting one can be quite the challenge. Their clever camouflage works just as well on humans as it does on their most common predator – birds. While males have a tiny abdomen measuring only 2.5mm long, it’s the females that make their presence known at a sizeable 2cm long. Their broad, triangular abdomen, decorated in sploshes of white and brown, easily resembles bird poo and with its legs tucked tightly against its body, it’s easy to see why this creature tends to go unnoticed.
A master of disguise, the bird-dropping spider uses another clever trick to trap its prey. Feeding almost exclusively on male moths, the spider hangs from the edge of a leaf or twig on a short silk thread at night-time, with its legs outstretched. Releasing a chemical scent that impersonates the airborne sex pheromone released by female moths to attract a mate, the spider lurches and grabs any male moth that flies in for a closer look.
Reproduction is a little left of centre for the bird-dropping spider, with females constructing a series of large marble-shaped brown balls or egg sacs, held together with silk. As many as 13 sacks, each containing 200 eggs, are as big as the spider itself and look almost like a miniature piece of art as they hang from a tree branch. The female sits on top of the impressive structure by day and dangles below by night, awaiting unsuspecting moths who might fly by.
| Details | Description |
| Type | Invertebrate |
| Group | Arachnid – Spider |
| Other Common Names | Death’s Head Spider, Orchard Spider |
| Identifying Characteristics | A squat black, brown and cream coloured spider, 12 mm (female) or 2.5 mm (male). The abdomen is broad and triangular in shape, with a pair of rough humps towards the rear. |
| Distinctive Markings | Shape, colour pattern and resting position help this spider look like a bird dropping. It usually holds its legs folded in against its body. |
| Diet | Carnivore. Mainly eats male moths. |
| Habitat | Found in open woodlands and urban gardens. |
| Native Status | Native to Australia |
Although classified in the orb-weaving spider family Araneidae, this spider does not make an orb web. Instead it simply hangs by a short thread of silk from a leaf at night, with its legs outstretched, waiting for prey. This would not be a productive feeding strategy, except that the spider emits a chemical that mimics the pheromone of certain female moths; the male moths are fooled and, following the scent trail, are seized by the spider. During the day it sits exposed on a leaf surface, motionless and with legs tightly drawn against its body. With its mottled brown and white colour pattern it looks like a bird dropping and is ignored by predators such as birds.
What do Bird-dropping Spiders look like?
Identification
One of the best known Bird-dropping Spiders is Celaenia excavata. Other names for this spider are the Death’s Head Spider, as its markings can also resemble the shape of a skull, and the Orchard Spider, because it is often seen on fruit trees where moths, its main source of food, may be abundant.
Its large size, distinctive colour pattern and resting posture all make this dung mimicking spider hard to mistake. The abdomen is broad and triangular in shape, concave along midline, and has a pair of roughened humps towards the rear. The legs are usually held folded against body.
Where do Bird-dropping Spiders live?
Distribution
The Bird-dropping Spider is found throughout much of eastern and southern Australia and have even been recorded from Uluru in central Australia. They are moderately common in suburban gardens but often overlooked.
What do Bird-dropping Spiders eat and how do they mate?
Feeding and diet
Like its relatives the Bolas Spiders, The Bird-dropping Spider also uses mimicry of a quite different sort to capture its prey, which consist almost exclusively of male moths. At night the Bird-dropping Spider hangs from the edge of a leaf or twig on a short silk thread, its forelegs outstretched. While doing this it releases a chemical scent (pheromone) that mimics the airborne sex pheromone released by female moths to attract their mates. The unfortunate male moths that are attracted by the spider’s deceiving pheromone eventually flutter close enough to the spider to be grabbed by its strong front legs.
In some areas, such as near Brisbane, it has been recorded that the prey consists only of male Lawn Armyworm Moths, Spodoptera mauritia, family Noctuidae. But in the Canberra area, where S. mauritia does not usually occur, a spider was recorded to catch two different but common species also from the family Noctuidae. A female noctuid and non-related species were occasionally caught, indicating that other moths that blunder past will be taken.
Other behaviours and adaptations
Despite its large size, this squat, black, brown and white spider sits huddled on a leaf or branch during daylight hours, often in quite exposed positions. Its colouration and immobile posture fools predators into thinking that the spider is a blob of dung rather than a healthy meal.
Breeding behaviours
The egg sacs of the Bird-dropping Spider are large, marbled brown coloured balls, each about 12 mm in diameter and containing more than 200 eggs. Up to 13 sacs are silked together in a group, beneath which the spider may be found sitting by day or hanging by night awaiting prey.
Are Bird-dropping Spiders dangerous?
Danger to humans
The bite of this spider is not considered to be dangerous.
Usually no first aid is required. A cold pack can be applied to help reduce any pain or swelling at the site of the bite.
