Pampas Meadowlark (Leistes defilippii): request for information.

BirdLife species factsheet for Pampas Meadowlark

This discussion was first published as part of the 2019 Red List update. At the time a decision regarding the status of this species was pended, but to enable potential reassessment of this species as part of the 2020 Red List update this post remains open and the date of posting has been updated.

The Pampas Meadowlark (Leistes defilippii) was formerly common and widespread in the grasslands of east-central Argentina and Uruguay, but always rare in south Brazil. Since 1900, its range has decreased by 90%, with most of this decline occurring between 1900 and 1950 (Tubaro et al. 1994, Tubaro and Gabelli 1999). The species is currently found in northern and central Uruguay (Salto, Flores and Tacuarembó Departments; Azpiroz 2015) and central eastern Argentina (SW Buenos Aires and eastern La Pampa; MAyDS and AA 2017). There are no recent records from Brazil and the species is considered nationally extinct (MMA 2014).

In 1992-1993, the population in Argentina was estimated to number c.7,500 birds (Tubaro and Gabelli 1999). In 2004, a detailed study estimated a range contraction in Argentina of 30% within 10 years, but gave a higher estimate of population size (a minimum of 28,000 individuals; Gabelli et al. 2004). In Uruguay the breeding population was estimated at 78-90 pairs in the Arerunguá area (Azpiroz 2005), later revised to 150-200 pairs (Azpiroz et al. 2018). A further population of 50-70 individuals was recently discovered in Tacuarembó and a small population of 11-12 pairs was recorded in Flores (Azpiroz et al. 2018).

The species is currently listed as Vulnerable under Criteria A2ce+3ce+4ce; B1ab(i,ii,iii,iv,v). However, recent national red lists published for Argentina (MAyDS and AA 2017) and Uruguay (Azpiroz et al. 2018) both list the Pampas Meadowlark as Endangered at the national level. Hence, we are undertaking a review of the species’s Red List Category.

Our current information on the species’s conservation status will now be compared to all Red List Criteria.

Criterion A – In 2004, the Argentinian range was estimated to have contracted by 30% within 10 years (Gabelli et al. 2004).

Recent estimates for the population size in Argentina have included: c.7,500 individuals (equivalent to 5,000 mature individuals) in 1992-1993 (Tubaro and Gabelli 1999) and 28,000 individuals (equivalent to 18,667 mature individuals) in 2004 (Gabelli et al. 2004). However, the Argentinian Red List (MAyDS and AA 2017) states that the 2004 estimate was an overestimate, and surveys in 2011-2014 have found a population size 10% smaller than that estimated in 1992-1993. This would equate to a reduction of 6.5% over three generation lengths (12.9 years).

The Argentinian Red List also states that the current population in Argentina is less than 2,500 mature individuals (MAyDS and AA 2017), although the provenance of this figure is not explained. A decline from 5,000 mature individuals in 1992-1993 to 2,500 in 2017 would equate to a reduction of 30% (assuming exponential decline) over three generation lengths (12.9 years).

According to the Argentinian Red List, the population is estimated to undergo a reduction of 50 – 80% over a period of three generation lengths that includes both the past and the future, based on direct observation and reduction of the extent of occurrence and habitat quality (MAyDS and AA 2017). However, no further information is provided on how this reduction was calculated, and further quantitative evidence for the magnitude of the reduction would be required to enable us to use this reduction estimate to assess the species under Criterion A.

In the Arerunguá area in Uruguay, only five pairs were recorded during the 2016 breeding season, and 15-20 pairs in the 2017 breeding season in an area thought to have contained 100-140 pairs in the last decade (Azpiroz et al. 2018). If this reduction is assumed to have taken place over ten years, this is equivalent to a reduction of >90% across three generations (12.9 years, assuming exponential decline). However, this is based on few counts and the Arerunguá area holds a small proportion of the species’s total population.

Based on the evidence described, the species is estimated to have undergone an overall reduction of between 11% and 44% across three generations (12.9 years), meaning that it could be assessed as Vulnerable, Near Threatened or Least Concern under Criterion A. If further evidence supports the assertion that the Argentinian population is likely to undergo a reduction of more than 50% across three generations, the species may be assessed as Endangered under Criterion A.

Criterion B – The species’s Extent of Occurrence (EOO) is estimated at 144,541 km2, rounded to 145,000 km2. This does not approach the threshold for listing the species as threatened under Criterion B1. The species is therefore assessed as Least Concern under Criterion B1.The species’s Area of Occupancy (AOO) has not been quantified, but based on a 4 km2-grid placed over the area of mapped range, must be smaller than 16,064 km2. This does not meet the threshold for Vulnerable under Criterion B2. Should a more accurate measurement of the species’s area of occupancy (calculated according to IUCN guidelines) become available, the species may be reassessed under this Criterion.

Criterion C – Recent estimates for the population size in Argentina have included: c.7,500 individuals (equivalent to 5,000 mature individuals) in 1992-1993 (Tubaro and Gabelli 1999) and 28,000 individuals (equivalent to 18,667 mature individuals) in 2004 (Gabelli et al. 2004). However, the Argentinian Red List (MAyDS and AA 2017) states that the 2004 estimate was an overestimate, and surveys in 2011-2014 have found a population size 10% smaller than that estimated in 1992-1993, which would equate to a population size of 4,500 mature individuals. Additionally, the Argentinian Red List states that the current population in Argentina is smaller than 2,500 mature individuals (MAyDS and AA 2017), although the provenance of this figure is not explained. The Argentinian population size is therefore likely to fall within the band 2,000-4,500 mature individuals.

In Uruguay the breeding population was estimated at 78-90 pairs in the Arerunguá area (Azpiroz 2005), later revised to 150-200 pairs (Azpiroz et al. 2018), equivalent to 300-400 mature individuals. However, during the 2017 breeding season, only 15-20 pairs (equivalent to 30-40 mature individuals) were recorded in the Arerunguá area in an area thought to have contained 100-140 pairs in the last decade (Azpiroz et al. 2018). A further population of 50-70 individuals (equivalent to 33-47 mature individuals) was recently discovered in Tacuarembó and a small population of 11-12 pairs (22-24 mature individuals) was recorded in Flores (Azpiroz et al. 2018). The population size in Uruguay is therefore likely to fall within the band 85-471 mature individuals.

The total population size is therefore estimated to fall within the band 2,085 – 4,971 mature individuals, here rounded to 2,000 – 5,000 mature individuals. Depending on whether the actual population size falls below 2,500 mature individuals, it may meet the threshold for listing the species as Endangered or Vulnerable under Criterion C. However, to list the species as threatened on the Red List under Criterion C further conditions must also be met.

The Argentinian range is estimated to have contracted (Gabelli et al. 2004). The populations in Argentina and Uruguay are estimated to have undergone declines (MAyDS and AA 2017, Azpiroz et al. 2018), which are likely to be continuing. The Argentinian Red List states that the Argentinian population has undergone a decline of 20% in five years or two generations, but no further evidence is provided to support this estimate. For a rate of decline to be used to fully assess a species under Criterion C1, the rate must be based on observed, estimated or projected population size changes.

In the Arerunguá area in Uruguay, only 15-20 pairs were recorded in the 2017 breeding season in an area thought to have contained 100-140 pairs in the last decade (Azpiroz et al. 2018). If this reduction is assumed to have taken place over ten years, this rate of decline would meet the thresholds for Critically Endangered, Endangered and Vulnerable under Criterion C1, when only looking at this subpopulation. However, this is based on few counts and the Arerunguá area holds only a very small proportion of the species’s total population, and so may not be representative to scale up to the global level.

The species may be considered to have at least two separate subpopulations. The largest of these, in Argentina, is estimated to number 2,000-4,500 mature individuals, meaning that the species would not meet condition 2a(i). The Argentinian subpopulation is estimated to represent 92– 98% of the total population, meaning that it precautionarily meets condition 2a(ii) at the level Endangered. There is no evidence that the species’s population size is undergoing extreme fluctuations so the species doesn’t meet condition 2b.

Based on the information stated above, the species could qualify for listing as Endangered or Near Threatened under Criterion C2a(ii), depending on individual subpopulation sizes and whether or not the population size falls below 2,500 mature individuals. Since neither conditions 2a(i) or 2a(ii) are met at the level of Vulnerable, the species cannot currently be assessed as Vulnerable under Criterion C2 based on the information currently available. Pending further information regarding trends, it may also trigger a listing of at least Near Threatened under Criterion C1.

Criterion D – Based on the population estimate of 2,000 – 5,000 mature individuals, the species’s population size does not meet or approach the threshold for Vulnerable under Criterion D. The species does not have a restricted area of occupancy of number of locations such that a plausible future threat could drive the species to Critically Endangered or Extinct within a very short time. The species does not therefore meet the criteria for listing as Vulnerable under Criterion D2. The species is therefore assessed as Least Concern under Criterion D.

Criterion E – To the best of our knowledge no quantitative assessment of the probability of extinction has been conducted for this species, and so it cannot be assessed against this criterion.

To allow us to achieve a clearer assessment of the species’s status, the following information is requested:

  • The species’s population size and rate of decline across its range.
  • Further information to allow a quantitative assessment of the rate of decline in area of occupancy or extent/quality of habitat.

Please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’s Red List status. Therefore, please make sure your comments are about the proposed listing.

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

Azpiroz, A.B. (2015) Shiny Cowbird (Molothrus bonariensis) parasitism records for three globally threatened species from the South American Pampas. The Wilson Journal of Ornithology 127(4): 746-752.

Azpiroz, A.B., Jimenez, S. and Alfaro, M. (eds.) (2018) Libro rojo de las aves del Uruguay. Biologia y conservacion de las aves en peligro de extinction a nivel nacional. Categorias “Extinto a Nivel Regional”, “En Peligro Critico” y “En Peligro”. DINAMA and DINARA, Montevideo.

Fraga, R. (2018) Pampas Meadowlark (Leistes defilippii). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. and de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. Retrieved from https://www.hbw.com/node/62326 on 4 October 2018.

Gabelli, F.M., Fernández, G.J., Ferretti, V., Posse, G., Coconier, E., Gavieiro, H.J., Llambías, P.E., Peláez, P.I., Vallés, M.L. and Tubaro, P.L. (2004) Range contraction in the pampas meadowlark Sturnella defilippii in the southern pampas grasslands of Argentina. Oryx 38(2): 164-170.

MMA (2014) Lista Nacional Oficial de Espécies da Fauna Ameaçadas de Extinção. Portaria No 444, de 17 de dezembro de 2014. Diário Oficial da União – Seção 1. Nº 245, quinta-feira, 18 de dezembro de 2014.

MAyDS and AA (Ministerio de Ambiente y Desarrollo Sustentable and Aves Argentina) (2017) Categorización de las Aves de la Argentina (2015). Report of Ministerio de Ambiente y Desarrollo Sustentable de la Nación and Aves Argentinas. Buenos Aires, Argentina.

Tubaro, P. L. and Gabelli, F. M. (1999) The decline of the Pampas Meadowlark: difficulties of applying the IUCN criteria to Neotropical grassland birds. Studies in Avian Biology 19: 250-257.

Tubaro, P., Gabelli, F. and Gallegos-Luque, D. (1994) Red Data Bird: Pampas Meadowlark. World Birdwatch 16: 18-19.

This entry was posted in Americas, South America and tagged , , , . Bookmark the permalink.

1 Response to Pampas Meadowlark (Leistes defilippii): request for information.

  1. Hannah Wheatley (BirdLife) says:

    Based on available information, our proposal for the 2019 Red List is to pend the decision on this species and keep the discussion open until 2020, while leaving the current Red List category unchanged in the 2019 update.

    Final 2019 Red List categories will be published on the BirdLife and IUCN websites in December, following further checking of information relevant to the assessments by both BirdLife and IUCN.

Leave a Reply to Hannah Wheatley (BirdLife) Cancel reply

You have to agree to the comment policy.

This site uses Akismet to reduce spam. Learn how your comment data is processed.