Second-hand foraging: endangered red-tails feed research red-caps

Lauren Gilson.  For three months I have been measuring the evaporative water loss of Red-capped parrots and Western Rosellas.  Residents of the mesic (moist climate) habitats around Perth, these species are providing data for a larger exploration of water balance in Australian vertebrates.

First I had to catch the birds, which was not easy in itself.  Then I brought them into the ecophysiology lab at Curtin for study.  I use an open-flow respirometry system to quantify water loss by measuring the water content of air the bird breathes while at rest overnight.  The bird’s body temperature is measured with a passive integrated transponder.  Its breathing rate measured using plethysmography (which converts the small changes in air pressure from inhalation and exhalation into electrical pulses that can then be plotted and analysed).

A red-capped parrot.

These measurements require that the parrots are happy and healthy for the duration of my research study.  This can be as much of a challenge as capturing them, because they can be fussy!  Wild-caught parrots don’t seem to be particularly fond of the commerically-available “wild bird” seed mixes available on the markets – they eat the sunflower seeds, and leave the rest relatively untouched.

I am therefore grateful to the free-flying Red-tailed black cockatoos that have been foraging on a large lemon-scented gum which grows near the lab.  Thanks to the big cockies’ messy eating habits, I have been able to collect nicely “pre-cut” branchlets bearing buds and fruits in various stages of maturation, before they get squashed on the road, and provide them to the research-participant parrots housed in the aviary.

I also have been able to collect fresh gumnuts nipped from the marri tree near my home (thanks again, black cockatoos!).  Although some seeds have already been removed by their primary foragers, there is still plenty left.

This second-hand foraging on the bigger birds’ leaving likely occurs in the wild as well (Blanco et al. 2018), when red-caps take advantage of intact, dropped gumnuts on the ground below trees in fruit.

Both these supplemental “feeds” provide the red-caps and rosellas with natural food resources.  It also provides them the opportunity to behave naturally: to handle multiple gumnuts and manipulate them with beak and foot in search of the remaining seeds to extract, and to nip off the leaves, buds, and fruits from branches discarded by the foraging cockatoos.

Environmental enrichment is important for animals in captivity, especially those that were free-roaming. The experience of capture and captivity is phsyiologically and mentally stressful for wild birds (Dickens et al., 2009), so being able to perform normal behaviours such as food handling likely helps to reduce the stress of captivity (Rodrigues-Lopez 2016).


Blanco, G., Hiraldo, F., and Tella, J.L. (2018). Ecological functions of parrots: an integrative perspective from plant life cycle to ecosystem functioning. Emu – Austral Ornithology, 118:1, 36-49. DOI: 10.1080/01584197.2017.1387031

Dickens, M.J., Earle, K.A., and Romero, L.M. (2009). Initial transference of wild birds to captivity alters stress physiology. General and comparative endocrinology160(1), pp.76-83.

Rodriguez-Lopez, R. (2016). Environmental enrichment for parrot species: Are we squawking up the wrong tree?. Applied Animal Behaviour Science180, 1-10.

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