Short-term sustainable collection of eggs and nestlings of the endangered Carnaby’s cockatoo (Zanda latirostris)

Introduction

Although species conservation tends to focus on protecting rather than using wildlife, sustainable use has been advocated as a viable conservation strategy for some threatened species (Campbell 2002; Cooney et al. 2017), but not without a diversity of concerns or views from stakeholders (Hart et al. 2013).

Sustainable use in the form of commercial tourism interactions with threatened species is common with cetaceans (Samuels et al. 2003), pinnipeds (Kirkwood et al. 2003), and fish (Haskell et al. 2015; Anna and Saputra 2017). Webb (2002) provided an argument for conservation through sustainable use using the saltwater crocodile (Crocodylus porosus) in northern Australia and the hawksbill turtle (Eretmochelys imbricata) in Cuba as case studies. Other research has outlined the economic value and incentives to conserve Australian native birds and reptiles using an ecologically sustainable framework for commercial use of wildlife where there was a net conservation advantage (ACIL Economics 1997).

Sustainable harvesting is the taking of individuals of a species from the wild without affecting the overall population numbers of the species (Beissinger and Bucher 1992). Examples of sustainable harvesting programs based on the collection of saltwater crocodile eggs in the Northern Territory (Webb 2002) of Australia and the commercial harvesting of kangaroos are well documented (Grigg 1995; Grigg and Pople 2001; Webb 2002). More recently a similar approach has been advocated for the conservation of tropical Asian freshwater turtle species (Rachmansah et al. 2020).

Cockatoos are recognised globally for their extraordinary plumage, mimicry ability, and charismatic nature (White et al. 2012), and the combination of high levels of endemism in Australian parrots and cockatoos and strict export regulations means species such as black cockatoos (Calyptorhynchus spp. and Zanda spp.) command very high prices on overseas markets (Barry 2011; Vall-llosera and Cassey 2017). Limited legal supply, and demand for sought-after species creates incentives for poaching them from the wild (Vall-llosera and Cassey 2017).

Beissinger and Bucher (1992) advocated for the sustainable harvesting of parrots provided their biology was well understood and overall population numbers were not affected. The profits from such sustainable harvesting could then be used to conserve the habitat of parrots. Vardon et al. (1997) proposed a program to sustainably harvest red-tailed black cockatoos (Calyptorhynchus banksii) in the Northern Territory. That program would provide incentives to landowners to conserve the cockatoos by giving the species an economic value. Vardon et al. (1997) also suggested that a price decrease for captive birds as a result of the proposed program could provide a dis-incentive for poaching. However, they did not have a sufficient understanding of the biology of the species to implement the program and did not test whether their idea was viable.

The biology of Carnaby’s cockatoo (Zanda latirostris Carnaby, 1948) is well known. The species start breeding at 3–4 years of age (Saunders and Ingram 1998; Dawson et al. 2013) and commence breeding between late winter and spring, with egg laying taking place between July and November (Saunders 1982). Once paired, they remain together all year and nest in large natural hollows in the trunks of large Eucalyptus trees (Saunders 1982, 1990). The nestlings remain in the nest for 70–77 days before fledging (Saunders 1982; Saunders and Dawson 2018). Carnaby’s cockatoos normally lay two eggs in a clutch with a mean interval between laying the first and second egg of 8 days (Saunders 1982). Producing the second egg takes relatively little energy and it acts as insurance in the case of the first egg failing (Stoleson and Beissinger 1996; Ehrlich et al. 1988). While both eggs hatch in 77% of two-egg clutches, the breeding pair normally only fledge one young per year because the second nestling usually dies within 48 h of hatching (Saunders et al. 2014, 2016). As incubation begins with the first egg, the younger nestling is usually visibly smaller than its older sibling and thus can be easily identified in the nest. The demise of the second nestling may be due to maternal neglect or sibling competition (Saunders et al. 2014).

Although Carnaby’s cockatoos generally lay two eggs per breeding cycle, clutch size is affected by seasonal factors such as the onset of autumn–winter rainfall in some parts of its range (Saunders et al. 2013). Carnaby’s cockatoos time the production of their young to coincide with the availability of food resources and use the onset of autumn rainfall as a cue to start breeding (Saunders et al. 2013). When the onset of rainfall is delayed, Carnaby’s cockatoos respond by delaying the start of their breeding and in some cases also by reducing the size of their clutch (Saunders et al. 2013). Therefore, in years with a late onset of rainfall and less winter rainfall, Carnaby’s cockatoos generally lay only one egg. If a breeding attempt fails early enough in the breeding season, the breeding pair move to another nest hollow and re-lay (Saunders 1990). Williams et al. (2017) estimated survival rate for adult Carnaby’s cockatoos of 92.7% (95% CI 89.7–95.7%) and for fledglings 60% (95% CI 36–84%). Saunders et al. (2024) were able to calculate adult and fledgling annual survival rates from a long-term study data set as being 87.4% for adults and 19.5% for fledglings. While the adult survival rates in the two studies are similar, the difference in the estimated and calculated fledgling survival rates provides a salient lesson in the risks in relying on estimates in population modelling.

Since the 1940s, Carnaby’s cockatoos have suffered a 30% contraction in range, a 50% decline in population, and have disappeared from more than a third of their original breeding range (Saunders 1990; Saunders and Ingram 1998; Saunders et al. 2021). In 1996, Carnaby’s cockatoo was declared as ‘rare or likely to become extinct’ and in 1997, its IUCN rank was upgraded from Vulnerable to Endangered. Carnaby’s cockatoo is now listed as endangered under the Australian Federal Government’s Environment Protection and Biodiversity Conservation Act 1999, as Endangered under the Western Australian Biodiversity Conservation Act 2016, and listed as Endangered under IUCN Red List category and criteria (IUCN 2021). The species has a national recovery plan, which lists the main threats affecting the species. These are a loss of feeding and breeding habitat due to land clearing or land degradation, competition for nest sites, climate change, collisions with motor vehicles, disease, mining and extraction activities, illegal shooting, and poaching (Department of Environment and Conservation 2012).

In 1996, poaching was lucrative, partly due to the high market price of Carnaby’s cockatoos (between AUD1100 per bird and AUD3000–$5000 per pair) and partly due to their very poor breeding success in captivity (Saunders 1976; Mawson 1997). Poaching has a detrimental impact on populations of wild Carnaby’s cockatoos due to the loss of birds from the wild population and to the damage caused to nesting hollows during the poaching process (White et al. 2012). In addition, poaching can also lead to problems such as introducing invasive species at the end point of the transport sequence, loss of biodiversity, and transmission of zoonotic diseases (Choisy and Rohani 2006; White et al. 2012). Often trees are cut down or the nest hollows are damaged by poachers, and this then makes these sites unsuitable for future breeding attempts (Saunders 1979; Department of Environment and Conservation 2012).

Between 1991 and 2008, there were 39 prosecutions brought to Western Australian courts against individuals for illegal dealings with Carnaby’s cockatoo, resulting in 14 convictions (Department of Environment and Conservation 2012). However, it is difficult to estimate the true impact and extent of illegal poaching due to its clandestine nature (Coghlan et al. 2012; Sánchez-Mercado et al. 2021). Until recently, it was difficult for the compliance officers to detect cases of poaching and courts were unable to impose penalties that provided a meaningful deterrent. New developments in forensic technology have helped in the detection of illegal poaching. For example, White et al. (2012) used DNA from eggshells recovered from a nest to successfully match a nestling to a nest hollow from which it was poached and used a provenance population database (nest sites) to identify the kinship and geographic origin of another cockatoo illegally removed from the wild. In these two cases, the DNA evidence helped to achieve successful prosecution of those who had illegally taken cockatoos from the wild. However, for most cockatoo and parrot species, there is still a lack of DNA reference databases, which limits the ability to detect poaching through DNA analysis (Coghlan et al. 2012). Until very recently (2019), the available maximum penalties for poaching wildlife, and particularly threatened species, were less than the monetary value that could be obtained for a Carnaby’s cockatoo on the international market and those penalties were discretionary (i.e. penalties were imposed at the magistrate’s discretion up to a maximum limit and were not mandatory as is the case in other Western Australian legislation such as fisheries legislation). The Australian Environment Protection and Biodiversity Conservation Act 1998, which was not enacted until 2000, provides for larger financial penalties for illegal poaching of listed threatened native fauna, but it is difficult to determine what influence, if any, that this legislation had on decision-making by poachers as there have only been three prosecutions under this legislation reported in the media with respect to Carnaby’s cockatoo and they were all for illegal clearing of breeding habitat. The enactment of the EPBC Act may well have altered the markets that poachers targeted, as the risk of exporting fertile eggs or nestlings on their (the poachers’) person may have represented too great a risk, but it would not have influenced the movement of poached eggs and nestlings within Australia. Increased enforcement alone is not enough to stop poaching as it does not address the underlying drivers of poaching (i.e. the high monetary benefits; Challender and MacMillan 2014). Ways of addressing the high monetary benefit of poaching could be to drive down the market price for Carnaby’s cockatoos, increase penalties for poaching significantly, or both.

To discourage poaching, the then Department of Conservation and Land Management (CALM) reasoned that the market price for Carnaby’s cockatoos needed to be driven down as there was little prospect of penalties for poaching being significantly increased at that time. One way to decrease the market price was to increase supply to the domestic aviculture market through a short-term sustainable harvesting program in which Carnaby’s cockatoos were taken from the wild as eggs or nestlings and hand reared and sold into the market en masse to drive down the price.

Previously, Beissinger and Bucher (1992) had shown that parrots could be sustainably harvested, providing that they are harvested at a rate approximately equivalent to, or slightly less than the productivity of the population. In Western Australia, a program was conducted for the Naretha blue bonnet (Northiella haematogaster narethae) from 1991 to 1994 where founding stock were collected from the wild, maintained in captivity, and the progeny sold under licence into the domestic market. This program was successful in reducing the market price and reducing the incentive for illegal trapping and nest robbing in the wild (Menkhorst 1997).

Given the success of the collecting program for the Naretha blue bonnet, CALM embarked on a similar program for Carnaby’s cockatoos. However, since Carnaby’s cockatoos have poor breeding success in captivity (Saunders 1976), this program necessitated collecting eggs and nestlings from the wild. These were then hand reared by pre-selected licenced aviculturists, with a share of the birds that were collected being returned to CALM to be sold onto the open market by public tender at the end of the program. The scientific basis for the program was that since Carnaby’s cockatoos raise one nestling and generally ignore the second one, taking only one egg or nestling should have limited impact on wild source population. Given the ability of Carnaby’s cockatoos to produce a second clutch when the first clutch fails in the early part of the breeding season (Saunders 1982), under favourable field conditions and reliable food supplies, it could be possible to take a sole surviving egg or nestling without impacting on field fledging success if the measure of reproductive output is based on nest hollows rather than breeding pairs. It was decided that eggs or nestlings would be collected rather than adult cockatoos because nestlings adapt more easily to life in captivity and their collection has less impact on wild populations as nestlings have a lower survival rate than adults in the wild (Saunders 1988; Beissinger and Bucher 1992; Beissinger 2001; Williams et al. 2017). The program was not expected to impact wild Carnaby’s cockatoo population as it was only run in an area that represented a small part of the population distribution within the northern part of the species range. Even if the local population of Carnaby’s cockatoos in this program was significantly affected, through catastrophic events at a local level such as heat waves, disease outbreaks, and hailstorms (Saunders et al. 2011), the overall population of Carnaby’s cockatoos should not be so affected.

The long generation time (>15 years) of Carnaby’s cockatoos means that any negative impacts on breeding success will not be evident in wild population levels for many years (Saunders and Ingram 1998; Department of Environment and Conservation 2012). Therefore, to determine whether the program had any effect on breeding success, the rate at which nestlings successfully fledge to the wild needed to be measured and compared to the fledging rate which would be expected in the absence of the program.

The aim of this study was to determine whether Carnaby’s cockatoos could be sustainably collected from the wild using a short-term program to achieve conservation objectives such as influencing market price and discouraging poaching without affecting population fledging rates. A secondary aim of this project was to investigate whether the market price of Carnaby’s cockatoos decreased following the egg or nestling collection program.

We asked three additional questions to explore the factors that influenced whether the program affected fledging rates: (1) whether nests with one egg or one nestling that have been manipulated were less productive than those with two eggs or nestlings; (2) whether nests where the larger nestling was removed were less productive than those where the smaller nestling was removed; and (3) if nests with eggs removed were less productive than those where nestlings were removed.

Materials and methods

In 1996, both nestlings and eggs were collected, while in 1997 and 1998, only nestlings were collected because nestling survival to 3 months of age in 1996 was found to be greater for those taken as nestlings rather than eggs. In the 1996 season, the eggs and nestlings were collected from the northern wheatbelt over an area ranging from Coorow (29.88°S, 116.02°E) in the north, and southwards to the northern parts of the Gingin Shire (30.89°S, 116.04°E). In 1997 and 1998, the nestlings were collected over a 190-km range extending from the Local Government Authority (LGA) of Coorow in the north to the LGAs of Chittering and Victoria Plains in the south, with the bulk of the birds coming from the more southerly LGAs. Five licensed private aviculturists incubated and hatched the eggs and raised the nestlings. All costs associated with the collection of eggs and nestlings and the monitoring of the outcome of breeding in each nest hollow were met by CALM, and all costs associated with the raising of the birds were met by the aviculturists. The Department’s share of the Carnaby’s cockatoos were sold onto the market by public tender at the end of the program in 1999, meaning that some of the cockatoos were 1 year old, others were 2 years old, and the remainder were 3 years old.

During the 1996 breeding season, CALM staff monitored 68 nest trees that contained 70 Carnaby’s cockatoo nests. In 1997 and 1998, they monitored 40 nest trees containing 40 nests. A total of 133 individual nest trees were monitored across the 3-year program. Nests were monitored up until the end of the second breeding cycle to confirm the fledging rates of the nests from which eggs or nestlings were collected, as Carnaby’s cockatoos often lay a second clutch if their first breeding attempt is unsuccessful. When Carnaby’s cockatoo breeding pairs fail during their first attempting early in the breeding season, they may relay, but always in a different nest and usually not far from the nest used in the first attempt (Saunders 1982). To examine the survival rates of the nestlings raised in captivity, we calculated the percentage of the total number of nestlings collected that survived.

Results

Did the program successfully reduce market price?

In the years leading up to the program, the price of Carnaby’s cockatoos rose from AUD2000 in 1990 to AUD4500 in 1996. In the years during and after the program, the price declined from AUD4500 in 1996 to AUD 2800 (AUD1658 in 1996 dollars terms adjusted for inflation) in 2018 (Fig. 1). Regression analysis showed that there was a significant downward linear trend in price levels from 1996 to 2018 (y = −111.27x + 225,890; R² = 0.8342; F_(1,21) = 110.41, P < 0.001).

Fig. 1.

Variation in the price of Carnaby’s cockatoos (Zanda latirostris) between 1990 and 2018 expressed in 1996 dollar terms. The regression line shows the trend from 1996 to 2018.

The price of the similar red-tailed cockatoos also decreased significantly from AUD4000 in 1990 to AUD2000 (AUD1184 in 1996 dollar terms adjusted for inflation) in 2018 (Fig. 2). Regression analysis showed that there was a significant downward trend in the market price of red-tailed cockatoos over this time period (y = −117.57x + 238,450; R² = 0.9041; F_(1,21) = 198.02, P < 0.001).

Fig. 2.

Variation in the price of red-tailed cockatoos (Calyptorhynchus banksii) between 1990 and 2018 expressed in 1996 dollar terms. The regression line shows the trend from 1996 to 2018.

Black cockatoos are large birds that require expansive flight aviaries for optimal welfare. At the same time as the price of black cockatoos was declining (Figs 1 and 2), there was a similar trend in the average lot size for private dwellings associated with new land releases and infill of older and larger lots (Tables 2 and 3; ABS 2020).

Table 2.Changes in average site area of new houses in Australian capital cities (from 2005–2006 to 2019–2020).

	2005–2006 (m2)	2019–2020 (m2)	Change from 2005–2006 to 2019–2020 (m2)	% Change from 2005–2006 to 2019–2020
Greater Sydney	654	447	−207	−32
Greater Melbourne	597	463	−134	−22
Greater Brisbane	618	497	−121	−20
Greater Adelaide	634	531	−103	−16
Greater Perth	575	427	−148	−26
Australian capital cities (combined)	602	467	−135	−22

Table 3.Changes in average floor area of new houses in Australian capital cities (2005–2006 to 2019–2020).

	2005–2006 (m2)	2019–2020 (m2)	Change from 2005–2006 to 2019–2020 (m2)	% Change from 2005–2006 to 2019–2020
Greater Sydney	280	252	−28	−10
Greater Melbourne	230	253	23	10
Greater Brisbane	209	246	37	18
Greater Adelaide	208	223	15	7
Greater Perth	243	222	−21	−9
Australian capital cities (combined)	234	248	14	6

At the same time that lot size was declining across the country, the average floor area of dwellings built on those lots remained more or less the same (ABS 2020), meaning that area available for large external structures like flight aviaries for black cockatoos was being reduced even more.

Discussion

This study examined whether a short-term sustainable collecting program for Carnaby’s cockatoos conducted by CALM was successful in reducing the market price of Carnaby’s cockatoos, without adversely impacting fledging success in the wild source population in the northern wheatbelt of Western Australia. The results showed that during the 3-year program fledging success from nests involved in the program was not significantly different to fledging success observed in the wild in the absence of clutch manipulation. At the same time the market price for Carnaby’s cockatoos decreased and remained low after the program. This suggests that the program may well have been successful in reducing market prices while not adversely affecting fledging success of Carnaby’s cockatoos in the wild.

Fledging success was significantly lower in 1997 than in 1996 and 1998. This can be attributed to the lower autumn rainfall (154 mm in 1996, 137 mm in 1997 and 214 mm in 1998; Badgingarra Research Station; Bureau of Meteorology 2019) and the resulting smaller average clutch size in 1997 (Saunders et al. 2013, 2019). The short-term sustainable collecting program had an adverse effect on fledging success during this drier year, as the majority of clutches laid that year were one-egg clutches and removing the one egg or nestling from those nests resulted in more failures due to the lower incidence of second clutches being laid. Longer-term declines in annual rainfall have also been shown to have a significant, negative impact on fledging success, nestling condition and fledgling survival, suggesting that Carnaby’s cockatoo may not be a suitable species for any such future programs, at least not in those parts of its current range most affected by a drying and warming climate (Saunders et al. 2024). This has important implications for any future programs, and demonstrates the importance of fully understanding the biology of a species in order to undertake such programs. Any future sustainable collecting programs for Carnaby’s cockatoos should not be carried out in years with a low autumn and or winter rainfall. Any future sustainable collecting programs for any cockatoo species need to ensure that seasonal factors affecting breeding are fully understood, and taken into account when developing sustainable collection plans.

In 1996 and 1997, fledging success was greater when nestlings were collected from nests with two nestlings than from nests with one. This further demonstrates that to maximise the chance of fledging success in the target nests, nestlings should be collected from nests containing two nestlings. Fledging success was also greater when eggs were collected as opposed to nestlings. This was because for the majority of nests where no nestling has yet hatched, there were two eggs; whereas in the majority of nests where the nestlings have hatched, there is invariably (>94%) only one nestling more than 14 days old (Saunders et al. 2014). This means that the window of opportunity to maximise the collection from two-egg/nestling clutches while having the least likelihood of affecting the success of the nest is small, typically only 8–10 days when both nestlings are still alive.

Survival rates in captivity were significantly lower in 1996 than in 1997 and 1998. In 1996, both eggs and nestlings were collected and in 1997 and 1998, only nestlings were collected. This was due to some eggs being infertile or cracked at the time of collection. Based on this finding, it is recommended that future short-term sustainable collecting programs collect only nestlings to ensure maximal survival rates in captivity, so long as this approach does not compromise nest hollow productivity (as distinct from breeding pair productivity) within the target population. It made no difference to either fledging success or captive survival rates whether the younger or older nestling was collected. Therefore, future programs do not necessarily have to consider whether they are collecting the younger or older nestling so long as there is still another nestling or egg remaining in the nest.

The removal of any animals from populations of threatened species may run the risk of adversely affecting the genetics of those populations. This is more likely to occur in populations that are either geographically isolated, short-range endemics, contain few remaining animals or have non-random mate choice systems. None of those risks is likely to be relevant to Carnaby’s cockatoos. Genetic analysis of a large sample of Carnaby’s cockatoos, including all the fledglings raised in this program, indicated that this species has a single population, despite its large (900 km north-south) geographic range (White et al. 2014). The mating system of this species is also not strictly one of long-term monogamy, with 27% of second eggs in two-egg clutches being sired by a male other than the male that sired the first egg (Saunders et al. 2018). Finally, there is inequity in the proportion of male and female nestlings that return to their natal breeding area, with more males dispersing away to the breeding grounds of their chosen mate (Saunders 1982).

The ASWA data showed that the suggested market price of Carnaby’s cockatoos increased in the years immediately leading up to the short-term sustainable collecting program and subsequently declined and remained low. Details of the proposed program were publicised in the 2 years leading up to its implementation and sellers, and logically poachers were aware of the program before its commencement. This could have led to a reduction in the supply of Carnaby’s cockatoos, pushing up their market price. Another reason for the initial rise in prices could also be related to advances in DNA technology (McInnes et al. 2005), which meant that the likelihood of being successfully prosecuted for poaching cockatoos or receiving poached birds had increased. This had the effect of drying up the supply of allegedly legally bred birds.

After the sale of the Carnaby’s cockatoos onto the market, the market price dropped, suggesting that this program may have been successful. However, there are alternative explanations for the drop in the market price of Carnaby’s cockatoos in the years following the program considering that the price fell for a similar species (the red-tailed cockatoo) at the same time. Owning a large, noisy bird such as a Carnaby’s cockatoo requires a large area to keep it without adversely affecting the amenity of near neighbours. Since the 1990s, average housing lot sizes have declined significantly by an average 22% across the five greater capital cities of mainland Australia (Table 2; ABS 2020) and at the same time, the average size of dwellings being built on those lots increased by an average of 6% during the same period (Table 3; ABS 2020). This means that people have less space to keep Carnaby’s cockatoos and there is subsequently less demand for Carnaby’s cockatoos, which may have resulted in the observed reduction in market price. The decrease in demand for Carnaby’s cockatoos could also be attributed to shifts towards a busier lifestyle with less time for keeping a Carnaby’s cockatoo or simply changes in consumer preferences, with consumers lately becoming more aware of environmental issues and thus less likely to keep an iconic native species as a pet (Damania and Bulte 2007). By comparison, the red-tailed cockatoo, which is a much easier species to breed in captivity, showed a similar decline in market price over the same period, without a sustainable collection program having been implemented. This suggests that the decline in market prices may have been due to factors unrelated to the sustainable collection program. The fact that the price remained low years after the program had ended also suggests that the price decrease may be mainly driven by a decrease in demand rather than the effects of the sustainable collecting program. However, since this research was correlational, cause and effect cannot be determined, and it is therefore difficult to determine whether the decline in pricing can be attributed predominantly to the effects of the program or to other factors such as those described above.

The current study only examined changes across time in the market price of Carnaby’s cockatoos based on recommended prices obtained from the ASWA newsletter. This is only one source of indicative prices and needs to be interpreted in terms of what disposable income levels were before, during, and after the 3-year program. It may also be useful to look at prices from classified advertisements of the time to see whether these also showed a similar price decrease. While we only examined changes in the market price, many cases of selling poached birds take place on the black market. Due to the clandestine nature of the black market, it would be extremely difficult to obtain black market prices, but it would be interesting to see whether prices on the black market were also affected by the decline in market prices. It is expected that since Carnaby’s cockatoos can now be legally purchased at a lower price, the incentive to purchase them on the black market would be reduced. However, there is still a ban on the overseas export of native Australian wildlife (Kingwell 1994) and the higher prices that can be obtained for Carnaby’s cockatoos on international markets compared to the domestic market creates incentives for poachers to sell Carnaby’s cockatoos on the overseas black market.

There were very few (<1 per annum) prosecuted cases involving the illegal taking of Carnaby’s cockatoos both before and after the program was carried out, which makes it difficult to draw any solid conclusions regarding whether poaching rates changed after the program. The limited data suggest that there was no significant difference in prosecution rates pre- and post- the program. This may be a result of the small sample size of cases prosecuted during the project time-frame, but could also be a function of resourcing directed towards investigating such activities, or the development and application of modern forensic DNA technology to counter poaching (White et al. 2012).

The short-term sustainable collecting program was only designed to partially address the threat to Carnaby’s cockatoos from poaching, which is only one of many threats that this species is facing, with other threats such as land clearing, climate change, and road mortality also posing significant risks (Saunders et al. 2011; Department of Environment and Conservation 2012). While decreasing the risk of poaching is important in reducing the extinction risk of Carnaby’s cockatoos, it is also important to address other threats to maximise the chance of survival for the species. Conservation programs to improve breeding success without stopping habitat clearing are likely to fail (Cockerill et al. 2013). Therefore, any repeat of this program should only be run in conjunction with programs designed to limit habitat clearing as well as those aimed at revegetating areas within the current range of Carnaby’s cockatoo. It is also not realistic to expect that the proceeds of small-scale programs such as the one described in this paper could make a significant contribution towards meeting the costs of other necessary conservation actions.

The results of this research showed that fledging success of nestlings left in the monitored nests was not significantly impacted by the short-term sustainable collecting program. It is expected that this would translate into the number of adult Carnaby’s cockatoos in the wild population being unaffected by the program, all other factors post-fledging being equal. Either way, the scale of the program was not large enough to have had an impact on the local population of Carnaby’s cockatoos and there would be no need to run the program on a larger scale as the objectives of the program had already been achieved. Furthermore, there would be insufficient demand to warrant the sale of a larger number of Carnaby’s cockatoos onto the market. The success of this program provides cautious support for the implementation of similar short-term sustainable collecting programs to protect other endangered species or to achieve specific conservation outcomes. Based on this study, several recommendations are made:

Conclusion

This study showed that Carnaby’s cockatoos can be sustainably collected from the wild as part of short-term programs without significantly affecting fledging success of local populations. The market price of Carnaby’s cockatoos also decreased following the program, although it is difficult to determine whether this effect can be attributed solely to the program. This program is the first study to show that an endangered cockatoo species can be successfully collected from the wild without affecting fledging success and thus local wild population levels.