Archived 2020 topic: Costa Rican Ground-sparrow (Melozone cabanisi): revise global status?

BirdLife species factsheet for Costa Rican Ground-sparrow

Costa Rican Ground-sparrow (Melozone cabanisi) is endemic to Costa Rica, where it occurs in a small area in the Central Valley, the Turrialba Valley and the Monteverde Mountains. The species occupies a variety of habitats, from secondary forests and patchy woodland to shaded coffee plantations and thickets at altitudes between 500 and 2,100 m (Sandoval et al. 2014, del Hoyo et al. 2020). The species is common and regularly observed throughout its range del Hoyo et al. 2020, eBird 2020). The population size is estimated to number fewer than 50,000 mature individuals (Partners in Flight 2019); therefore, it is placed here in the band 20,000-49,999 mature individuals.

Even though Costa Rican Ground-sparrow occupies a variety of habitats, the species seems more and more threatened by land-use change, especially by the conversion of shaded coffee plantations and thickets into urban and suburban habitats (Sandoval et al. 2014, del Hoyo et al. 2020). This habitat conversion furthermore benefits the Bronzed Cowbird (Molothrus aeneus), which is a common brood parasite of Costa Rican Ground-sparrow (del Hoyo et al. 2020). Local declines have been recorded so that overall, the species is feared to be undergoing a moderate decline (Partners in Flight 2019, del Hoyo et al. 2020).

Costa Rican Ground-sparrow is currently listed as Least Concern (BirdLife International 2020). However, new information regarding the population trend suggests that the species may warrant a change in Red List status. Therefore, it will be re-assessed against all Red List criteria:

Criterion A – The population trend has not been estimated directly. Partners in Flight (2019) report that the decline has been moderate, i.e. likely between 15% and 50% between 1970 and 2017 (see Panjabi et al. 2019). This roughly equates to a decline of 3-14% over ten years for this species (one generation length being 2.4 years; Bird et al. 2020)*. This value is too low to approach the threshold for Vulnerable (≥ 30% over ten years). Therefore, Costa Rican Ground-sparrow may be listed as Least Concern under Criterion A.

Criterion B – The Extent of Occurrence (EOO) for this species is 5,300 km2. This value meets the threshold for Vulnerable (EOO < 20,000 km2) under Criterion B1. However, in order to be listed under this criterion, at least two further conditions have to be met.

Costa Rican Ground-sparrow is found throughout its range. As such, there is no evidence to suggest that the species is severely fragmented sensu IUCN (IUCN Standards and Petitions Committee 2019). The most severe threat to the species is the expansion of urban and suburban areas into its thicket habitat. This threat however is limited to a small geographic scale and mainly affects the area around San José and other major settlements in the Central Valley. It would therefore need a large number of threatening events in order to severely affect the population and as such, the number of locations** of occurrence is likely very large. Therefore, the species does not meet condition a.

The species’s preferred habitat is being converted, the risk of brood-parasitism by the Bronzed Cowbird is increasing and population is suffering from local declines. Based on this information, we can infer an ongoing decline in the area, extent and quality of habitat and in the number of mature individuals. Costa Rican Ground-sparrow thus meets condition b(iii,v). There is no evidence of extreme fluctuations in the distribution range or population size, and condition c is not met.

Overall, the species meets only one further condition. Therefore, Costa Rican Ground-sparrow may be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion B1b(iii,v)

Criterion C – The population size of Costa Rican Ground-sparrow has been placed in the band 20,000-49,999 mature individuals. This is too large to approach the threshold for Vulnerable (< 10,000 mature individuals). Therefore, the species may be listed as Least Concern under Criterion C.

Criterion D – The population size is too large to approach the threshold for Vulnerable (< 1,000 mature individuals). Therefore, Costa Rican Ground-sparrow may be listed as Least Concern under Criterion D.

Criterion E – To the best of our knowledge no quantitative analysis of extinction risk has been conducted for this species. Therefore, it cannot be assessed against this criterion.

Therefore, it is suggested that Costa Rican Ground-sparrow (Melozone cabanisi) be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion B1b(iii,v). We welcome any comments on the proposed listing.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of its Red List status. Therefore, please make sure your comments are relevant to the discussion outlined in the topic. By submitting a comment, you confirm that you agree to the Comment Policy.

*Bird generation lengths are estimated using the methodology of Bird et al. (2020), as applied to parameter values updated for use in each IUCN Red List for birds reassessment cycle. Values used for the current assessment are available on request. We encourage people to contact us with additional or improved values for the following parameters; adult survival (true survival accounting for dispersal derived from an apparently stable population); mean age at first breeding; and maximum longevity (i.e. the biological maximum, hence values from captive individuals are acceptable).

**The term ‘location’ refers to a distinct area in which a single threatening event can rapidly affect all individuals of the taxon present, with the size of the location depending on the area covered by the threatening event. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat (IUCN 2001, 2012).

An information booklet on the Red List Categories and Criteria can be downloaded here and the Red List Criteria Summary Sheet can be downloaded here. Detailed guidance on IUCN Red List terms and definitions and the application of the Red List Categories and Criteria can be downloaded here.

References

Bird, J. P.; Martin, R.; Akçakaya, H. R.; Gilroy, J.; Burfield, I. J.; Garnett, S.; Symes, A.; Taylor, J.; Šekercioğlu, Ç.; Butchart, S. H. M. (2020). Generation lengths of the world’s birds and their implications for extinction risk. Conservation Biology online first view.

BirdLife International. 2020. Species factsheet: Melozone cabanisi. http://www.birdlife.org (Accessed 14/02/2020).

eBird. 2020. eBird: An online database of bird distribution and abundance [web application]. eBird, Ithaca, New York. http://www.ebird.org (Accessed 14 February 2020).

IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K.

IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1. Second edition. IUCN Species Survival Commission. IUCN, Gland, Switzerland and Cambridge, U.K. www.iucnredlist.org/technical-documents/categories-and-criteria.

IUCN Standards and Petitions Committee. 2019. Guidelines for using the IUCN Red List Categories and Criteria. Version 14. http://www.iucnredlist.org/documents/RedListGuidelines.pdf.

del Hoyo, J.; Collar, N.; Kirwan, G. M. 2020. Costa Rican Ground-sparrow (Melozone cabanisi). In: del Hoyo, J.; Elliot, A.; Sargatal, J.; Christie, D. A.; de Juana, E. (eds). Handbook of the Birds of the World Alive. Lynx Edicions. Barcelona, Spain. https://www.hbw.com/node/1344147 (Accessed 14 February 2010).

Panjabi, A. O.; Easton, W. E.; Blancher, P. J.; Shaw, A. E.; Andres, B. A.; Beardmore, C. J.; Camfield, A. F.; Demarest, D. W.; Dettmers, R.; Keller, R. H.; Rosenberg, K. V.; Will, T. 2019. Avian Conservation Assessment Database Handbook, Version 2019. Partners in Flight Technical Series No. 8. http://pif.birdconservancy.org/acad_handbook.pdf.

Partners in Flight. 2019. Avian Conservation Assessment Database, version 2019. http://pif.birdconservancy.org/ACAD.

Sandoval, L.; Bitton, P.-P.; Doucet, S. M.; Mennill, D. J. 2014. Analysis of plumage, morphology, and voice reveals species-level differences between two subspecies of Prevost’s Ground-sparrow Melozone biarcuata (Prévost and Des Murs) (Aves: Emberizidae). Zootaxa 3895(1): 103-116.

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3 Responses to Archived 2020 topic: Costa Rican Ground-sparrow (Melozone cabanisi): revise global status?

  1. Red List Team (BirdLife International) says:

    The window for consultation is now closed. We will analyse and interpret the new information and post a preliminary decision on this species’s Red List status on this page in early July.

    Thank you,
    BirdLife Red List Team

  2. Red List Team (BirdLife International) says:

    Preliminary proposal

    Based on available information, our preliminary proposal for the 2020 Red List would be to adopt the proposed classification outlined in the initial forum discussion.

    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 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

  3. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Costa Rican Ground-sparrow is recommended to be listed as Near Threatened, approaching the threshold for listing as threatened under Criterion B1b(iii,v).

    Many thanks for everyone who contributed to the 2020 GTB Forum process. The final 2020 Red List categories will be published on the BirdLife and IUCN websites in December 2020/January 2021, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Comments are closed.