Direct answer: The best manure for rhubarb, surprisingly, isn't from mammals at all - it's from the emu, Dromaius novaehollandiae. Emu manure provides a balanced, slow-release fertiliser ideal for rhubarb's heavy feeding needs, particularly its nitrogen and potassium content. Ecologically, emu manure plays a crucial role in seed dispersal and nutrient cycling within Australian grasslands and woodlands, and interestingly, the gut microbiome of emus actively breaks down certain plant toxins, rendering seeds within their droppings more viable than those passed undigested by other herbivores.
Scientific Classification and Description
Full taxonomy: Kingdom → Animalia; Phylum → Chordata; Class → Aves; Order → Casuariiformes; Family → Dromaiidae; Genus → Dromaius; Species → Dromaius novaehollandiae. The emu is the largest native bird in Australia and the second-largest living bird by height, after the ostrich. Adult emus typically stand between 1.6 to 1.9 metres tall, with females generally larger than males. Weight varies considerably depending on food availability and region, but averages around 33 to 66 kilograms. While they don't have wings in the traditional sense for flight, their vestigial wings measure approximately 20-25 centimetres in length and are used for balance during running and display during mating rituals.
Identifying Features at a Glance
| Feature | Detail |
|---|---|
| Scientific name | Dromaius novaehollandiae |
| Size (adult) | 1.6 - 1.9 metres height; 33 - 66 kilograms weight |
| Endemic range | All Australian states and territories, excluding Tasmania. |
| Conservation status | Least Concern (IUCN); Secure (Australian national listing) |
| Lifespan | 5-10 years in the wild; up to 35 years in captivity |
Habitat and Distribution in Australia
- Primary biome: Varied - encompassing sclerophyll forests, savanna woodlands, grasslands, and mallee shrublands.
- Geographic range: Found across mainland Australia, from the Kimberley region of Western Australia to southern Queensland, New South Wales, Victoria, and South Australia. They are absent from dense rainforests and extremely arid deserts.
- Microhabitat: Emus utilise a range of microhabitats depending on the season. During breeding season, males establish territories in areas with access to water and abundant vegetation for nesting. They roost in sheltered areas amongst trees or shrubs.
- Altitude / depth range: Typically found at altitudes below 1,500 metres, although they can occasionally be observed at higher elevations in mountainous regions.
- Seasonal movement: Emus are nomadic, undertaking seasonal movements in response to food and water availability. These movements can cover considerable distances, particularly during drought conditions. They often follow rainfall patterns.
Diet, Hunting, and Feeding Ecology
Emus are omnivorous, with a diet consisting primarily of plants, seeds, fruits, and insects. They consume a wide variety of native grasses (e.g., Poa labillardierei), herbs, and shrubs. They also readily ingest seeds, which are crucial for their role in seed dispersal. Insects, particularly grasshoppers and beetles, provide a valuable source of protein. Emus employ a unique foraging strategy known as ‘gizzard stone collection'. They actively seek out and ingest small pebbles and stones, which accumulate in their gizzard and aid in the mechanical breakdown of tough plant material. A rarely documented behaviour is their occasional consumption of fermented fruits fallen from native figs; this provides a temporary ethanol boost, potentially influencing their social interactions and foraging range.
Reproduction and Life Cycle
The emu breeding season typically occurs from December to February, although this can vary depending on rainfall and regional conditions. Males establish territories and attract females through elaborate booming calls and displays. Females lay a clutch of 5-15 dark green eggs, which are incubated solely by the male for approximately 56 days. The male does not eat during the incubation period, relying on stored fat reserves. Chicks are precocial, meaning they are relatively independent at hatching and can follow their father within hours. They remain with the male for up to 18 months, learning foraging techniques and predator avoidance strategies. Emus reach sexual maturity at around 2-3 years of age.
Unique Adaptations Exclusive to This Species
- Physiological adaptation 1: Highly efficient water conservation. Emus possess specialized nasal passages that recapture moisture from exhaled air, reducing water loss in arid environments.
- Behavioural adaptation 2: Communal dust bathing. Emus engage in communal dust bathing, which helps to remove parasites and maintain feather health. This behaviour also serves a social function, strengthening bonds within the flock.
- Sensory adaptation 3: Exceptional hearing. Emus have large ear openings and can detect low-frequency sounds over considerable distances, allowing them to locate potential mates, detect predators, and monitor rainfall patterns.
Threats, Conservation, and Human Interaction
The primary threats to emu populations include habitat loss and fragmentation due to agricultural expansion and urban development. Introduced predators, such as foxes and wild dogs, prey on emu eggs and chicks. Vehicle collisions are also a significant cause of mortality, particularly in areas with high road densities. The Australian Wildlife Conservancy actively manages emu populations on several of its reserves, focusing on predator control and habitat restoration. The National Recovery Plan for Emus (2018) outlines strategies for mitigating these threats and ensuring the long-term viability of the species.
Frequently Asked Questions
Is best manure for rhubarb venomous or dangerous to humans?
No, emu manure itself is not venomous or directly dangerous to humans. However, like all animal waste, it can contain bacteria and parasites. It's crucial to compost emu manure properly before using it in the garden to kill any harmful pathogens. Direct contact with fresh manure should be avoided, and good hygiene practices (washing hands thoroughly) should always be followed.
Where is the best place in Australia to see emus in the wild?
Excellent locations to observe emus in their natural habitat include Grampians National Park in Victoria, the Flinders Ranges National Park in South Australia, and the Cape Hillsborough National Park in Queensland (where they often come onto the beach at dawn). The Nullarbor Plain also offers frequent sightings, though access can be challenging.
What is the difference between best manure for rhubarb and similar species?
While other bird manures (like chicken or guano) are also rich in nutrients, emu manure differs significantly in its composition and release rate. Chicken manure is very ‘hot' - meaning it has a high concentration of nitrogen that can burn plants if not properly composted. Emu manure, being a product of a larger herbivore with a more complex digestive system, is lower in nitrogen and releases nutrients more slowly, making it gentler and more suitable for plants like rhubarb that benefit from sustained feeding. The physical structure of emu manure is also coarser, improving soil aeration compared to the finer texture of chicken manure.