Collared Crow (Corvus pectoralis): revise global status?

Collared Crow (BirdLife Species factsheet) is currently listed as Near Threatened, on the basis that it is  suspected to be undergoing a  moderately rapid population reduction that may approach the thresholds for listing as Vulnerable (30-49% decline over a three generation period, which is 21.9 years for this species). The global population size was considered likely to exceed 10,000 mature individuals based on an extrapolation from a high density observed in Hong Kong, hence placed in a band of 10,000 – 19,999 mature individuals. However, it has become evident that it is highly localised throughout the very large range, and this extrapolation from the density encountered in Hong Kong was inappropriate (P. Leader in litt. 2016, Leader et al. 2016).

Recent efforts to improve the accuracy of the global population estimate have been conducted through a combination of an exhaustive compilation of historical and recent records and targeted field surveys at different locations within the range (Leader et al. 2016). This has resulted in a far lower estimate of the total population size of around 2,000 individuals (Leader et al. 2016). No attempt was made to account for the potential presence of additional, unsampled locations holding numbers of the species during the assessment, and there are reports of this species at locations not included in the Leader et al. (2016) population estimate (S. Chan in litt. 2017). Therefore, this estimate should be taken as the lower bound of a population estimate rather than a mid-point.

The exercise did unearth a significant concentration of the species in eastern central China. Centred on the Dabie Shan mountain range in Henan, Hubei and Anhui provinces, an estimated 400-500 individuals were observed in the area over the course of a week in December 2014 (Leader et al. 2016). This indicates that additional localities with notable numbers may well be found. However, the presented estimate does represent a careful assessment of observations of the species, and it is unlikely that additional localities would increase the estimate by a large margin. Therefore, with careful consideration of the estimates presented for the multiple locations holding the species in Leader et al. (2016), the population is placed here in the band of 2,500 – 9,999 mature individuals.

The population structure does still require some clarification, though. While the centres of population are discrete and often distant from each other, reports of individuals or small groups between these may indicate a low level of continuing connection between locations, and with the apparent extirpation of the mainland Chinese Taiwan population (where there have been only three records in recent decades, with the most recent in 1987 [Leader et al. 2016]) no localities are divided by significant geographical barriers. Coupled with the apparent homology of the phenotype throughout the range, it could therefore be assumed that the species is made up of only a single subpopulation.

In light of the above, it is proposed that Collared Crow C. pectoralis meets the thresholds for listing as Vulnerable under Criterion C2a(ii), though we welcome any comments on the above points.

Reference

Leader P. J.; Stanton, D. J.; Lewthwaite, R. W.; Martinez, J. 2016. A review of the distribution and population size of Collared Crow Corvus torquatus. Forktail 32: 41-53.

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7 Responses to Collared Crow (Corvus pectoralis): revise global status?

  1. HUANG Hanchen says:

    I think Collared Crows are scarce in Beijing.

    Personally, I’ve seen three times of this species in Beijing on 8 April 2017 (one bird at Shahe Reservoir), 1 Jan 2018 and 20 Jan 2018 (both at Dashihe River, maybe the same individual).

    I’ve read the great Article by Paul Leader et al. from Forktail Number 32 (2016). Several records from North China were not involved in this extensive collection.

    Beijing –
    Before 1994 (the year of the publication of A Key to the Vertebrates of Beijing, GAO Wu, CHEN Wei, FU Biqian & WANG Caihua, Beijing Publishing House):
    Collared Crow was considered as a resident of Beijing. During 1980-1986 & 1988-1990, a bird survey at Yuanmingyuan Park (aka. Old Summer Palace) that was implemented by several institutions reported this present in the park, often mixing with other crows in winter. Some other distributional sites included Daxing District, Dahongmen (at Fengtai District), and Chaoyang District.
    2006:
    1 at Miyun Reservoir, Miyun on 5 May (WU Qi & anniebai, http://www.szbird.org.cn/birdtalker.net/reportview.asp?id=6704)
    2007:
    1 at Shahe Reservoir, Changping on 28 Jan (LI Haitao et al., http://www.szbird.org.cn/birdtalker.net/reportview.asp?id=8842)
    2008:
    1 at Songshan NNR, Yanqing during 9-12 Jun (CUI Yue et al., http://www.szbird.org.cn/birdtalker.net/reportview.asp?id=15511)

    (1/3, to be continued)

    HUANG Hanchen

  2. HUANG Hanchen says:

    2013
    1 at Beijing on 24 Mar (‘nature’ via birdnet.cn, http://www.birdnet.cn/forum.php?mod=viewthread&tid=470458. NOTE: some photographers may upload photos at the local forum but the photos might be taken from anywhere)
    2014:
    1 at Shidu, Fangshan on 12 Oct (ZENG Xiangle et al., http://www.szbird.org.cn/birdtalker.net/reportview.asp?id=45355)
    2015:
    1 at Shidu, Fangshan on 8 Feb (QIAO Yingxin, http://www.birdreport.cn/Member/WatchRecord?id=1068)
    1 at Shidu, Fangshan on 12 Apr (GAO Xiangyu, http://www.birdreport.cn/Member/WatchRecord?id=2070)
    2016:
    1 at Beijing Botanical Garden, Haidian on 1 Feb (XIAO Hong et al., http://bbs.cbw.org.cn/forum.php?mod=viewthread&tid=351682)
    1 at Wild Duck Lake, Yanqing on 16 Nov (‘Leshanshui’ via birdnet.cn, http://www.birdnet.cn/forum.php?mod=viewthread&tid=1897496. NOTE: the photo was posted on 16 Nov, but this date might not be accurate.)

    (2/3, to be continued)

    HUANG Hanchen

  3. HUANG Hanchen says:

    2017:
    1 at Shahe Reservoir, Changping on 8 Apr (HUANG Hanchen, https://ebird.org/view/checklist/S35777791)
    1 caged bird (said to be caught at Shunyi District, north of Beijing) near South 4th Ring Road on 28 May (per ZHANG Ming in litt.)
    1 at Kunyu River, Haidian on 13 Sep (‘Roadrunner’ via birdnet.cn, http://www.birdnet.cn/forum.php?mod=viewthread&tid=2674765. NOTE: the photo was posted on 13 Sep, but this date might not be accurate.)
    2018:
    1 at Dashihe River, Fangshan on 1 Jan (HUANG Hanchen & Luo Qingqing, https://ebird.org/view/checklist/S41490751)
    1 at Dashihe River, Fangshan on 20 Jan (HUANG Hanchen & Luo Qingqing, https://ebird.org/view/checklist/S42084385)

    (3/3, done)

    HUANG Hanchen

  4. HUANG Hanchen says:

    Also some records from other places in N & NE China:

    Tianjin –
    1 collected on 12 May 1933. Also could be seen at Tianjin Water Park and the plain area of urban and suburban. (see Fauna of Birds, Overall Annals of Tianjin, by WANG Fengqin, 2006)

    Nei Mongol –
    Only recorded at Alukerqin Banner, Chifeng and Ningcheng County, Chifeng. (Fauna Inner Mongolia, Vol.4, AVES Passeriformes, by Xurigan).

    Liaoning –
    Shenyang (see A Field Guide to the Birds of Northeast China, by CHANG Jiachuan et al., 1995), which is said to be the only place where Collared Crow had been recorded in NE China.

    Hope this comment will be helpful.

    HUANG Hanchen

  5. HUANG Hanchen says:

    Just forgot to post this:

    Hebei –
    Before 1931, LI Xiangyuan [H.Y.Lee] saw 8 mixed with Rooks near the railway at South Baoding (see Corvidae of Hebei Province, by LI Xiangyuan, Bulletin of the National Academy of Peiping Vol. 2 Issue 1, 1931). In that article, LI said Collared Crows were distributed all over Hebei Province and were more common in the plain area. They preferred to forage in the rice field, especially trench, riverside, brookside or dam on the plain. They feed on mollusks (such as snails) and crustacean (such as crabs).
    Dec 2013 at Qinhuangdao (GAO Hongying). Several photos could be seen on birdnet.cn. (http://www.birdnet.cn/forum.php?mod=viewthread&tid=243143, http://www.birdnet.cn/forum.php?mod=viewthread&tid=240795, etc.)

    HUANG Hanchen

  6. Rob Martin (BirdLife International) says:

    Preliminary proposals

    Based on available information, our preliminary proposal for the 2018 Red List would be to adopt the proposed classifications outlined in the initial forum discussion and list Collared Crow as Vulnerable under criterion C2a(ii).

    There is now a period for further comments until the final deadline in mid-July, after which the recommended categorisations will be put forward to IUCN.

    Please note that we will then only post final recommended categorisations on forum discussions where these differ from those in the initial proposal.

    The final 2018 Red List categories will be published on the BirdLife and IUCN websites in November, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  7. Ricardo Cavalieri says:

    The species is categorized as Near Threatened by China because it’s uncommon over the country with no significant/direct threat. That assessment could be reliable because many ornithologists took part in that project.

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