Longevity in Carnaby’s Cockatoo (Zanda latirostris) Carnaby, 1948

Introduction

Carnaby’s Cockatoo (Zanda latirostris) Carnaby, 1948 (family Cacatuidae) is a large (660 g), black bird, with a distinctive white sub-terminal tail band, endemic to south-western Australia (Saunders and Pickup 2023). It is classified as endangered by the Western Australian and Australian governments, as well as internationally (Saunders et al. 2021). Since European settlement, the species has lost much of its breeding and foraging habitat due to extensive clearing of native vegetation, primarily for agricultural development and urbanisation (Saunders et al. 1985). Sexes are the same size, but adult males have a black bill and a small dirty-white/pale-yellow cheek patch, while adult females have bone-coloured bills and large clear-white/pale-yellow cheek patches (Fig. 1). As they reach sexual maturity at three or four years of age (Saunders 1982; Dawson et al. 2013), the birds form pair bonds that last the life of one of the partners (Saunders 1982). In this paper, we examine the maximum recorded life span of Carnaby’s Cockatoo and compare that recorded life span with what is known of other long-lived bird species in the wild.

Fig. 1.

Pair of Carnaby’s Cockatoos (Zanda latirostris). Left, adult male; right, adult female (photograph Rick Dawson).

In examining the effects of potential land-use change on Carnaby’s Cockatoos, Williams et al. (2017) concluded that adult mortality has a profound effect on population viability; accordingly, it is necessary to understand longevity. Recently, DA Saunders, PR Mawson and R Dawson (unpubl. data) examined adult survival and lifetime reproductive success. In order to replace themselves and maintain a viable breeding population, they found that female Carnaby’s Cockatoos would have to live for at least 20–25 years.

In this paper, we use data from records of individually-marked wild Carnaby’s Cockatoos to establish the maximum recorded life span of Carnaby’s Cockatoo and compare these records with what is known of other long-lived bird species in the wild.

Materials and methods

Results

Eight Carnaby’s Cockatoos (five females and three males) with life spans of at least 21 years were recorded (Table 1). All but one were alive when resighted, and all but one were within 5.7 km of where they were banded. Three were adults when banded and their ages were recorded with a ‘+’ to indicate they were at least the age indicated, but may be have been older. Four years was added to the times between banding and last resighting to account for their juvenile period, as that was the recorded age at first breeding until recently (Dawson et al. 2013).

On 21 September 2021, adult male Carnaby’s Cockatoo with band number 210-03029 was photographed (Fig. 2) amongst a flock roosting in the south of the Coomallo Creek study area. The cockatoo and its leg band appeared to be in excellent condition. This sighting was the first time the cockatoo had been observed since the breeding season on 1986 when it fledged from a nest hollow 5.7 km from where it was photographed. Its estimated hatching date was 24 September 1986 and it was 35 years-old when photographed (Table 1). This is the oldest living Carnaby’s Cockatoo recorded in the wild.

Fig. 2.

Male Carnaby’s Cockatoo (Zanda latirostris) band number 210-03029 photographed on 21 September 2021, aged 35 years (photographs Rick Dawson).

Records of longevity of birds in the wild are based on records of banded/ringed individuals from studies of wild birds. Many of these studies have not been conducted long enough for research workers to answer the common question ‘How long do your birds live?’ Records from long-term central banding registers in Australia (ABBBS 2023; commenced 1953), USA (US-BBL 2023; commenced 1909), and UK (Robinson et al. 2022; commenced 1909) provide the most reliable records for the species in their jurisdictions. These registers, housing millions of records of original banding and subsequent sighting/recoveries of individual birds, show that seabirds tend to have the longest reported life spans. The species with the longest recorded life spans on the three registers are: (1) short-tailed shearwater (Ardenna tenuirostris) Temminck, 1836 found dead at 48 years and 4 months (ABBBS 2023); (2) Laysan albatross (Phoebastria immutabilis) Rothschild, 1893 recorded alive when it was 69 years and 9 months (US-BBL 2023); and (3) Manx shearwater (Puffinus puffinus) Brünnich, 1764 recorded alive at 50 years 11 months (Robinson et al. 2022).

The maximum life spans of species recorded by the Australian, American, and British band registers collated in decadal ranges are in Table 2. The data show that 96.5% of Australian, 94.5% of American, and 90.3% of British listed species had maximum recorded life spans of less than 30 years. The 31 species with maximum recorded life spans of 35 years or more on all three registers are in Table 3. All are non-passerines and 21 of the 31 species listed are seabirds.

The lists derived from the central banding registers are subject to change as more birds are individually marked and the number of records of recoveries/resightings accumulate. Ehrlich et al. (1988) listed maximum recorded life spans of 53 species from US-BBL records of September 1986. The 10 maximum life span records listed by Ehrlich et al. (1988) are in Table 4, together with their records at April 2023 (US-BBL 2023).

Discussion

The record of a living 35-year-old Carnaby’s Cockatoo (Fig. 2) at its breeding ground places this species in the top 2% of long-lived avian species recorded in the Australian, UK, and US bird band registers. When combined with the records of seven other Carnaby’s Cockatoos ranging from 21+ to ~34 years old, six of which were still breeding (Table 1), this species needs an extended reproductive life to counter the effects of mortality rates and/or low reproductive rates. Long-term studies of birds in the wild indicate that individuals within a population age at different rates, as measured by reproductive performance, and that birds do not often survive beyond their reproductive years (Curio 1989).

It is common knowledge that birds, particularly cockatoos and other parrots, live long lives in captivity. In line with this knowledge, there is a saying in Australia, that if you are given a cockatoo for your 21st birthday, you should make provision for it in your will as it will probably outlive you. In support of this saying, there have been several reports of cockatoos living to be more than 100 years old. For example, a sulphur-crested cockatoo (Cacatua galerita) Latham, 1790 was reputed to have died aged 120 years in Sydney in 1916 (https://www.smh.com.au/environment/conservation/sydneys-old-crock-of-a-cockie-was-a-legend-at-120201108311jkz2.html) – (accessed 20 August 2024). Another was reputed to have lived to 100 years old (&https://www.abc.net.au/news/20141102/wildlife-park-throws-a-100th-birthday-party-for-an-old-cockatoo/5860770?nw=0&r--=Interactive) (accessed 20 August 2024). However, these anecdotal reports are unsubstantiated.

In a review of longevity records of 176 species of Psittaciformes in captivity, Brouwer et al. (2000) noted that the life span of parrots in captivity rarely exceeds 50 years (4% of the taxa they reviewed), and that cockatoos appear to have both the longest life and reproductive spans. However, they acknowledged there were reliable records of parrots aged 65–70 years old. They cited two individuals: (1) a salmon-crested cockatoo (Cacatua moluccensis) Gmelin, JF, 1788 that died in San Diego Zoo, USA in December 1990 when it was 65 years old; and (2) a pink cockatoo (Cacatua leadbeateri) Vigors, 1831 at Brookfield Zoo, Chicago, USA, which at the time of writing, was at least 63 years and 7 months old. This individual died in August 2016, aged 83 years old. In fact, this is regarded by the Guinness Book of Records as the longest surviving bird, either in captivity or in the wild (https://www.guinnessworldrecords.com/world-records/442525-oldest-parrot-ever#:~:text=The%20oldest%20parrot%20ever%20is,away%20on%2027%20August%202016 accessed 20 August 2024).

Changes over time in the avian species that have the longest recorded lifespans can be dramatic (Table 4; Ehrlich et al. 1988). For example, Arctic tern (Sterna paradisaea) Pontoppidan, 1763 and American coot (Fulica americana) Gmelin, JF, 1789 records did not change, but the record for Laysan albatross increased by 34 years 4 months and the bird was still alive. The record for bald eagle (Haliaeetus leucocephalus) Linnaeus, 1766 increased by 16 years and 1 month, and great frigatebird (Fregata minor) Gmelin, 1789 by 13 years. This demonstrates the value of both long-term field studies of species that are faithful to studied breeding sites, and the value in re-analysing records at decadal or longer intervals.

Carnaby’s Cockatoo becomes sexually mature at 3–4 years old, pairs for life, displays natal site fidelity (females), lays two eggs, but usually fledges one young, breeds every year, has low survival in the juvenile years, high survival as adults, and is long-lived (Saunders 1982; Saunders and Dawson 2018; Saunders et al. 2018). All these characteristics are typical of the impressive oceanic wanderers, such as the albatrosses and petrels that are also in the 2% of avian species demonstrating long maximum recorded life spans.

Understanding how well the Carnaby’s Cockatoo copes with current conditions (Williams et al. 2017), and predicting what may happen in the future under conditions of changing climate requires further study to determine fledgling, juvenile, and adult survival rates. Once those rates are known, those core pieces of information can be combined with annual productivity and the species longevity and reproductive life-span to construct accurate life tables that can provide for informed decision making on where limited conservation investment can or should best be directed and in developing new species recovery plans for this species and other related black cockatoo species.