Archived 2020 topic: Taita Falcon (Falco fasciinucha): Request for Information

BirdLife International factsheet for Taita Falcon

The Taita Falcon is a small raptor, with a range from South Africa and Zimbabwe through Malawi and Tanzania to Kenya (BirdLife International, 2020). It favours roost sites in high cliffs, and hunts over savannah and dry woodland (Kemp et al. 2020). The current population estimate is 750-1500 individuals, roughly equating to 500-1000 mature individuals (BirdLife International, 2020).

The threats to this falcon include the encroachment of rural development and agriculture on habitat surrounding the breeding cliffs, and the loss of territories to larger falcons facilitated by the conversion of woodland to open habitats (Jenkins et al. in prep.).

The Taita Falcon has been considered Vulnerable under criteria C2a(i); D1. However, recent reports on population declines may warrant a change in Red List category. We have therefore reassessed the Taita Falcon here against all the criteria.

Criterion A: The Taita Falcon is believed to be in decline, following reports of decreases in breeding territories in South Africa and Zimbabwe. The generation length for this species has been recalculated to 4.1 years (Bird et al., 2020)*, and therefore rates of decline for this species are calculated over a length of 12.3 years.

Recent data for South Africa reports a 30% decrease in breeding individuals between 2011 and 2019 (A. Jenkins in litt. 2012; K. Walker pers. comm. 2020), equating to a 42% reduction rate over 3 generations. This is consistent with its current Vulnerable Red List category, however a 2013 survey in Zimbabwe found no territories in an area that once contained 12 breeding individuals c.1994 (Jenkins et al. 2019). This suggests that the Taita Falcon may be experiencing a more rapid decline, which may warrant uplisting to a higher threat category. However, according to IUCN guidelines, data representing declines from a few subpopulations can only be projected onto the rest of the range if those subpopulations were by far the largest subpopulation three generations ago, or if it can be assumed that all the other subpopulations are declining at the same rate (IUCN Standards and Petitions Committee, 2019).

The subpopulation structure of the Taita Falcon is poorly understood, and we are lacking trend data for populations in Kenya, Malawi and Tanzania. As a result, we cannot be certain that the declines recorded here are representative of the situation across its range. Should information arise demonstrating similar rates of decline in other countries of occurrence, this species may warrant uplisting to Endangered. We therefore seek information on population structures across its range, and information on trends in Kenya, Malawi and Tanzania. What are the local population sizes? If it is declining, what is the rate of decline, and what is causing the decline?

Criterion B: The Extent of Occurrence (EOO) for this species is still believed to be 2,690,000 km² (BirdLife International, 2020), which is too large to be considered threatened under this criterion. Taita Falcon would therefore be considered Least Concern under Criterion B.

Criterion C: The global population size estimate for this species remains at 500-1000 mature individuals (BirdLife International, 2020), which meets the threshold for classification as Endangered under this criterion (<2500 mature individuals). To fully qualify for assessment under criterion C, other requirements must be met. A continuing decline can be estimated from the continuing decrease in breeding territories. The population size is not believed to undergo extreme fluctuations. The subpopulation structure for this species is not fully understood, however as the population size is estimated to be <1000 mature individuals, we can assume that there are <1000 mature individuals in each subpopulation. Taita Falcon may therefore be considered Vulnerable under this criterion. However, new information on population structure may warrant a change in Red List category under this criterion. We therefore seek information on subpopulation structure: What is the number of subpopulations? How many individuals are in each subpopulation?

Criterion D: The global population size estimate of Taita Falcon remains at 500-1000 mature individuals. This reaches the threshold for Vulnerable (<1000 mature individuals). This species can therefore be considered Vulnerable under Criterion D1.

Criterion E: To the best of our knowledge, no quantitative analysis has been carried out for this species, so Taita Falcon cannot be assessed with this criterion.

In order to assess the Red List status of Taita Falcon, we therefore ask for recent information on the population size and subpopulation structure.

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’ Red List status. Therefore, please make sure your comments are relevant to the species’ Red List status and the information requested. 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).

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., Şekercioğlu, Ç.H. and 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: Falco fasciinucha. Downloaded from http://www.birdlife.org on 20/04/2020

IUCN Standards and Petitions Committee, 2019. Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Committee. Downloadable from http://www.iucnredlist.org/documents/RedListGuidelines.pdf.

Kemp, A.C., Kirwan, G.M. & Sharpe, C.J. (2020). Taita Falcon (Falco fasciinucha). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/53248 on 20 April 2020)

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8 Responses to Archived 2020 topic: Taita Falcon (Falco fasciinucha): Request for Information

  1. Darcy Ogada says:

    I would support the suggestion of a declining population in northern Kenya, and likely throughout the country. While there have been recent record(s) from one protected area, in habitats in northern Kenya where they used to be present, according to S. Thomsett, we have been unable to locate any individuals over a number of years. However, our surveys were not for this species and were not extensive, but given time spent in appropriate areas/times it is a species I would be very surprised to see at this point.

  2. In eight years working in Ethiopia and >10,800km of raptor roadcounts throughout the extent of the country from 2010 – 2017 documenting 22,909 individual raptors, our team has never seen a Taita Falcon in the country. However, barring targeted searches in suitable habitat any encounters would be highly unlikely, so the state of the species in the country remains uncertain.

  3. Red List Team (BirdLife International) says:

    Many thanks to everyone who has contributed to this discussion. We greatly appreciate the time and effort invested by so many people in commenting. 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 once again,
    BirdLife Red List Team

  4. Red List Team (BirdLife International) says:

    Preliminary proposals

    Based on available information, Taita Falcon is precautionarily suspected to be declining at a rate of >30% over three generations, but there is not enough evidence regarding rates of decline or subpopulation size and structure to list this species as Endangered.

    Therefore, our preliminary proposal for the 2020 Red List would be to list Taita Falcon as Vulnerable under Criterion A2ab; C2a(i); D1.

    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 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. The final publication date will be publicised by IUCN here: https://www.iucnredlist.org/assessment/updates

  5. In Tanzania this is a low density widespread species. A nest site on the NW face of the West Usambara was watched for several years. The next nearest on the Masai Steppe now has a small village below it. Records are scattered through western and SE Miombo where there are many (high hundreds-low thousands) suitable nest sites. Not a bird one can guarantee away from known nest sites but they are still out there. Very few records from such well watched sites as Ruaha NP and the Ngorongoro Highlands. Lanner Falcon are still common throughout the dry central plateau, Peregrines not at all common.

  6. Robin Colyn says:

    BirdLife South Africa have led annual surveys for the past decade in South Africa, together with focused surveys in Batoka Gorge. Results from surveyed sites in RSA, as well as Batoka reveal the sensitivity of this species. The Batoka surveys revealed a complete absence of the species, which considering its historical presence here is of conservation concern. Known areas of occupancy in both RSA and eslewhere face the common threat of habitat loss and fragmentation, compounded with decreased water quality within riparian catchments.
    Results from our long term study in RSA display that the species is a localized and low density resident that is significantly sensitive to the degradation and loss of climax woodland habitat surrounding appropriate cliffs. Furthermore,with change in land-use from woodland to agricultural and other open habitats the species is further pressured by the subsequent increase in larger falcon species (i.e. Lanner Falcons). It is our belief that this species faces a greater threat than previously believed and is in need of urgent conservation attention. Our results display a significant sensitivity to habitat degradation and loss, which ultimately leads to the local extirpation of the species if not addressed. Given the noted reduction of the species in currently surveyed areas, together with some areas yielding an absolute absence of the species, we suggest the species should be listed as Endangered (Criterion A2, C1 C2 & D1) until further research and evidence can suggest otherwise.

    Extract/Summary from published study:
    In the 1950s, the first Taita Falcon pair were located below Victoria Falls in the Batoka Gorge, Zimbabwe. Over the next 50 years, the upper 40 km of Batoka Gorge were regularly surveyed for Taita Falcons and larger congeners. In 1992, four breeding territories were occupied by Taita Falcons; the highest occupancy record to date. A total of six breeding Taita Falcon territories were identified by 1993, making Batoka Gorge the largest documented population of Taita Falcon in Africa. Regular surveys ceased after 1994 and in an isolated survey conducted in the 2006/7 season, only one historic breeding territory remained occupied. In July 2013 and November 2014, the South African Taita Falcon Survey Team attempted to re-survey the 40 km of the Batoka Gorge. The team amassed a total of 205 and 178 vantage point person hours respectively (Jenkins et al., 2019). No Taita Falcon were seen during each survey and all historic territories were occupied by larger congeners such as Peregrine and Lanner Falcon. Thus, based on the latest population survey, the Taita Falcon population in the Batoka Gorge has ceased to exist. However, the species is notoriously difficult to survey and there may still be isolated territories on the Zambezi River. This said, what was once considered a core Taita Falcon population, no longer exists. There are a number of factors which may have contributed to the Taita Falcon’s disappearance from Batoka Gorge and will likely influence other sub-populations across Africa. These include habitat change, decreased river water quality and anthropogenic disturbance. Over the past decade, there has been a 20% increase in agriculture and a 30% decrease in woodland density within a 2.4 km radius of the six historic Taita Falcon territories (Jenkins et al., 2019). These habitat changes are particularly suitable for the growing Lanner Falcon population, which did not occur in Batoka Gorge in the 1990s. The decline of water quality has an impact on invertebrate life and riparian vegetation. Furthermore, the avian community surrounding Batoka Gorge is indirectly influenced by river water quality. Thus, the decreased prey base may become detrimental to the Taita Falcons survival in Batoka Gorge. Finally, anthropogenic disturbance, such as helicopter and microlite flights in the Gorge, may have a negative influence on the surrounding raptor community. These influential factors are not limited to Batoka Gorge but are becoming ever more prevalent in the once isolated-cliffs that Taita Falcons occupy across Africa. As such, further research is required to better understand the species across their entire geographic range, but if Batoka Gorge is an indication of current population trends, the global status of the species should be reconsidered as Endangered.

    Jenkins, A.R., Zyl, A.J. Van, Magunje, I., Matsvimbo, F., Rodrigues, L., Robinson, L., Sebele, L., Tiran, D., et al. 2019. Status of the Taita Falcon (Falco fasciinucha) and Other Cliff-Nesting Raptors in Batoka Gorge, Zimbabwe. Journal of Raptor Research. 53(1):46–55. DOI: 10.3356/jrr-18-36.

  7. Robin Colyn says:

    Our data of over 10 years in RSA, together with a focused survey in Batoka Gorge, clearly displays a significant sensitivity to habitat loss, degradation and fragmentation. There’s a very distinct threshold where after the species s extirpated from the given area if habitat alteration (woodland) is not addressed. Furthermore, our results show a cumulative impact where the alteration of woodland to open habitats (agriculture, etc.) favors Lanner Falcon which in turn seems promote negative inter-species affects between the two falcon species. We have noted local nest sites abandoned from local known breeding sites, as well as entire sites such as Batoka Gorge where the species was not recorded. Given the low density, noted sensitivity to habitat degradation, and noted absence of the species at previously occupied localities; we believe the species warrants conservation concern and suggest the species be listed as Endangered (criterion A2ab; C2a(i); D1.)

    IUCN – Taita Falcons in Batoka Gorge

    In the 1950s, the first Taita Falcon pair were located below Victoria Falls in the Batoka Gorge, Zimbabwe. Over the next 50 years, the upper 40 km of Batoka Gorge were regularly surveyed for Taita Falcons and larger congeners. In 1992, four breeding territories were occupied by Taita Falcons; the highest occupancy record to date. A total of six breeding Taita Falcon territories were identified by 1993, making Batoka Gorge the largest documented population of Taita Falcon in Africa. Regular surveys ceased after 1994 and in an isolated survey conducted in the 2006/7 season, only one historic breeding territory remained occupied. In July 2013 and November 2014, the South African Taita Falcon Survey Team attempted to re-survey the 40 km of the Batoka Gorge. The team amassed a total of 205 and 178 vantage point person hours respectively (Jenkins et al., 2019). No Taita Falcon were seen during each survey and all historic territories were occupied by larger congeners such as Peregrine and Lanner Falcon. Thus, based on the latest population survey, the Taita Falcon population in the Batoka Gorge has ceased to exist. However, the species is notoriously difficult to survey and there may still be isolated territories on the Zambezi River. This said, what was once considered a core Taita Falcon population, no longer exists. There are a number of factors which may have contributed to the Taita Falcon’s disappearance from Batoka Gorge and will likely influence other sub-populations across Africa. These include habitat change, decreased river water quality and anthropogenic disturbance. Over the past decade, there has been a 20% increase in agriculture and a 30% decrease in woodland density within a 2.4 km radius of the six historic Taita Falcon territories (Jenkins et al., 2019). These habitat changes are particularly suitable for the growing Lanner Falcon population, which did not occur in Batoka Gorge in the 1990s. The decline of water quality has an impact on invertebrate life and riparian vegetation. Furthermore, the avian community surrounding Batoka Gorge is indirectly influenced by river water quality. Thus, the decreased prey base may become detrimental to the Taita Falcons survival in Batoka Gorge. Finally, anthropogenic disturbance, such as helicopter and microlite flights in the Gorge, may have a negative influence on the surrounding raptor community. These influential factors are not limited to Batoka Gorge but are becoming ever more prevalent in the once isolated-cliffs that Taita Falcons occupy across Africa. As such, further research is required to better understand the species across their entire geographic range, but if Batoka Gorge is an indication of current population trends, the global status of the species should be reconsidered as Endangered.

    Jenkins, A.R., Zyl, A.J. Van, Magunje, I., Matsvimbo, F., Rodrigues, L., Robinson, L., Sebele, L., Tiran, D., et al. 2019. Status of the Taita Falcon (Falco fasciinucha) and Other Cliff-Nesting Raptors in Batoka Gorge, Zimbabwe. Journal of Raptor Research. 53(1):46–55. DOI: 10.3356/jrr-18-36.

  8. Red List Team (BirdLife International) says:

    Recommended categorisation to be put forward to IUCN

    The final categorisation for this species has not changed. Taita Falcon is recommended to be listed as Vulnerable under Criteria A2ab; C2a(i); D1.

    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.

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