Alectura Research Articles

Selection of incubation mound sites by the Australian Brush‐turkey Alectura lathami

Environmental characteristics associated with siting of the incubation mounds of the megapode, the Australian Brush‐turkey Alectura lathami were investigated in three rainforest locations in southeast Queensland. Seventeen environmental variables were measured for 52 mounds and 137 non‐mound sites. Most mounds were constructed on top of old mounds which had not been used during the previous year. A Discriminant Function Analysis obtained a clear separation between mound and non‐mound sites, based primarily on three variables: (1) the number of saplings growing within the mound or centre of the site: this was considered to be a result of the germination of seeds raked in earlier years; (2) the proportion of Lantana camara thicket occupying the site. Approximately half of the mounds constructed during a season were abandoned by their constructor due to expulsion by a neighbouring male. Brush‐turkeys could more easily establish mounds next to thickets since the efficiency of defence by other males was reduced in these areas; and (3) the openness of the canopy. Areas with greater canopy cover provided two important mound resources: a good supply of leaf litter, and protection of the mound from dessication.

Sexual Interactions by Australian Brush-turkeys away from the Incubation Mound

Sexual Interactions by Australian Brush-turkeys away from the Incubation Mound

Dusting and Sunning by Australian Brush-turkeys

Dusting and Sunning by Australian Brush-turkeys

Gas exchange in the incubation mounds of megapode birds

The brush turkey (Alectura lathami) and mallee fowl (Leipoa ocellata) are megapode birds that incubate their eggs by burying them in mounds. Respiratory gas exchange between the buried eggs and the atmosphere occurs mainly by diffusion through about 60 cm of decomposing forest litter (brush turkey) or sand (mallee fowl).

Thermoregulation in Neonate Brush Turkeys (Alectura lathami)

Brush turkey neonates are able to thermoregulate between ambient temperatures of 10-38 C. They have a standard metabolic rate of 1.00 ± 0.04 ml O₂ • g⁻¹ • h⁻¹, within a thermoneutral zone extending from 29 to 38 C. Evaporative water loss is 2.57 ± 0.32 mg • g⁻¹ • h⁻¹ at temperatures below 38 C. Thermal conductance is 0.497 mW • g⁻¹ • C⁻¹ at temperatures below 29 C. Mean body temperature of homeothermic brush turkey hatchlings is 40.4 ± 0.2 C at ambient temperatures below 36 C. Chicks are unable to remain homeothermic at temperatures below 10 C when 5-16 h old but can cope with these temperatures after 24 h. Body temperature and evaporative water loss increase greatly at ambient temperatures greater than 39 C. Brush turkey and mallee fowl (Leipoa ocellata) neonates have similar body masses and thermal conductances, but brush turkeys have a higher standard metabolic rate, rate of evaporative water loss, and body temperature than do mallee fowl neonates and are less tolerant of thermal stress. These differences may reflect differences in the physical conditions of the posthatching environment. Brush turkeys inhabit jungle and thick scrub environments and hatch into a more mesic and cooler environment than do mallee fowl, which inhabit semiarid mallee areas.

Energetics of Embryonic Development in the Megapode Birds, Mallee Fowl Leipoa Ocellata and Brush Turkey Alectura lathami

Mallee fowl (MF) and brush turkey (BT) lay large, energy-rich eggs (173 g at 10.2 kJ/g contents for MF and 180 g at 9.8 kJ/g contents for BT) that are incubated by burial in mounds of warm earth or decaying vegetation. Their incubation periods of 62 days (MF) and 49 days (BT) are unusually long, and their hatchlings are among the most precocial of any birds. Metabolic rates of embryos of both species just prior to hatching are about 61 cm³ O₂/h, 98% (MF) and 64% (BT) higher than predicted. Metabolism is supported solely by chorioallantoic respiration until hatching, and pulmonary respiration begins suddenly when the shell membranes are torn. Estimates of total energy expenditure during incubation prior to hatching (Ei) based on O₂ consumption closely approximate estimates based on energy content of fresh eggs and hatchlings. The Ei are high (∼600 kJ for MF and ∼475 kJ for BT) because of the long incubation periods. Hatchlings must dig out of the incubation mounds, and costs of this may add 8% (MF) to 33% (BT) to the Ei before hatchlings reach the surface. Lower emergence costs and larger initial energy stores of MF eggs partly compensate for higher developmental costs, so chicks of both species begin life on the surface with similar energy reserves. The large yolks (>50% of egg contents) and high energy content of megapode eggs were essential adaptations in the evolution of a reproductive system in which embryonic development and hatchling behavior are energetically expensive.

Primitive Weaponry in Birds: The Australian Brush-Turkey's Defence

"Primitive Weaponry in Birds: The Australian Brush-Turkey's Defence." Emu - Austral Ornithology, 80(2), pp. 91–92

21. Some Observations on the Habits of the Brush Turkey (Alectura lathami)

21. Some Observations on the Habits of the Brush Turkey (<i>Alectura lathami</i>)