CR
Ridgway's Hawk Buteo ridgwayi



Justification

Justification of Red List Category
This species is listed as Critically Endangered because it has a small and fragmented population, which was previously in steep decline. Successful conservation action has now reversed such declines and the species is observed to be increasing throughout both its largest extant population in Los Haitises National Park and additional reintroduced populations. If population increases continue, it may be eligible for a downlist in the near future.

Population justification
This species has an extremely small and fragmented population, which was previously in steep decline, with a 21% reduction in breeding pairs from 2006-2009, and as few as 109 breeding pairs in 2009 (Woolaver 2011). In 2014 The Peregrine Fund recorded 120 territorial pairs in Los Haitises and two pairs in Punta Cana (The Peregrine Fund 2014). In 2016 they recorded 120 territorial pairs in Los Haitises and 12 pairs in Punta Cana (T. Hayes unpubl. data). In 2019, The Peregrine Fund recorded 142 pairs of Ridgway’s Hawks in Los Haitises and 19 pairs in Punta Cana. These 19 pairs of hawks successfully produced 17 fledglings in 2019 and two additional young were fostered into nests in Punta Cana. Additionally, some areas in Los Haitises are not being consistently monitored, however we know that some pairs of hawks continue to exist outside the monitored area. The total number of Ridgway’s Hawks is estimated at a minimum of 427 individuals and 322 mature individuals.

Trend justification
Until the past decade, the population of Ridgway's Hawks was observed to be in rapid decline, with monitoring exhibiting 5-10% annual population declines, which equates to declines of up to 80% over three generations (c.24.5 years). However, through successful conservation action, ongoing monitoring and hands-on management of nests/nestlings in Los Haitises shows that population decline has now reversed and is trending upwards. In Los Limones, one of four regions in Los Haitises where The Peregrine fund is managing the population, the number of pairs has grown from 37 pairs in 2011 to 76 pairs in 2019, a 105% increase in nesting pairs over 8 years (T. Hayes unpubl. data). Significant population increases are ongoing and this marked increase in the Ridgway’s Hawk population is a direct result of conservation efforts by The Peregrine Fund and their project partners.

Distribution and population

This species occurs in the Dominican Republic. It formerly also occurred in Haiti, with historical reports from the adjacent Haitian islands of Gonâve, the Cayemite Islands where it was reportedly common in 1934, Île-à-Vache where it was reportedly common in 1962 (Wiley and Wiley 1981) but is now likely extirpated (Brooks and Dávalos 2001), and in the Dominican islands of Isla Beata and Alto Velo. Recent surveys on Petite Cayemite Island and Grand Cayemite Island, Haiti report the first sightings of Ridgway’s Hawks there since 1918 (Wetmore and Swales 1931, Brooks and Davalos 2001). In August 2019, Haitian biologist Anderson Jean saw two Ridgway’s Hawks (one juvenile, one of unknown sex/age) on Petite Cayemite. In January 2020, Thomas Hayes (The Peregrine Fund) and Anderson Jean again reported two Ridgway’s Hawks (one adult female, one no confirmation on sex/age) on Petite Cayemite. Additionally, surveys during the same expedition found one adult female Ridgway’s Hawk on the adjacent island of Grande Cayemite (T. Hayes unpubl. data). There is a single record from the island of Culebra off Puerto Rico (to U.S.A.) (Raffaele et al. 1998). It was formerly widespread, but has been extirpated from over 96% of its original range during the last century (Woolaver 2011). There have been very few recent records outside Los Haitises National Park (S. Latta in litt. 1998). It was also recorded in human-modified habitat on the Samaná Peninsula in 2003 (Thorstrom et al. 2005). The species has been reported from Isla Beata and Valle Nuevo in 1981 (Wiley and Wiley 1981); both sites have not been surveyed significantly since then and confirmation of its status at these two sites is a priority. 

A new population is being established through releases of young birds at Puntacana Resort and Club, a private land holding in south-east Dominican Republic (The Peregrine Fund 2014, McClure et al. 2017). The first birds were released here in 2009. One pair successfully bred in 2013 and fledged the first known wild-hatched young outside of Los Haitises National Park (The Peregrine Fund in prep.). In 2016, there were 12 recorded territorial pairs in Punta Cana, of which five pairs were successful in fledging 8 young (The Peregrine Fund in prep.). The Peregrine Fund was also establishing a new population in the private reserve of Loma la Herradura by translocating individuals from the Los Haitises National Park (Thorstrom 2008); however, releases were suspended in 2013 due to high mortality of released hawks caused by human persecution (The Peregrine Fund 2014). In 2019, The Peregrine Fund released 25 juvenile Ridgway’s Hawks in Aniana Vargas National Park, with plans to continue releases until a population is established (T. Hayes in litt. 2020).

Ecology

The species has been recorded up to 2,000 m above sea level in a variety of undisturbed forest-types including rainforest, subtropical dry and moist forests, pine forest, limestone karst forest and marshland. It is often seen in secondary and agricultural habitats (Wiley and Wiley 1981) and appears to be attracted forest edges and human-inhabited areas (T. Hayes in litt. 2020). Prey in the Los Haitises consists primarily of reptiles (with lizards, in particular Celestus skinks [Woolaver et al. 2013c], and snakes comprising 80% of the diet) and frogs. They occasionally prey on birds, small mammals (bats and rodents) and centipedes (Woolaver 2011). Nests have been found in the crowns of tall endemic trees, with Royal Palms Roystonea hispaniolana particularly favoured (Woolaver 2005, 2006, 2011; Gesto 2018). Nest-building occurs in December-June and eggs are laid in January-June (Wiley and Wiley 1981, T. Hayes unpubl. data). The clutch size is 1-3 eggs. Pairs have successfully fledged three young, but more typically one or two. Males are known to participate in incubation. Disturbance by humans is sometimes a cause of nest failure (Woolaver 2011). The home range of three adjacent breeding pairs was just c.60 ha (Wiley and Wiley 1981).

Threats

Large-scale habitat loss due to clearing of forest for agriculture and pasture for livestock, as well as direct persecution have been major factors in this species's decline (Thorstrom 2004). Even within Los Haitises National Park, slash and burn agriculture is widespread; virtually all primary forest within the park has now been destroyed, and the remaining secondary fragments are being cleared at a rapid rate (Dirección Nacional de Parques 1991, Brothers 1997, Hayes et al. 2018). A study of nest success from 2005-2009 found that of 216 nests monitored, only 40% were successful, with the majority of nest failures caused by human disturbance, including burning or cutting of nest trees, poaching or intentional killing of eggs/nestlings, and rocks and sticks thrown at the nest (Woolaver et al. 2015). Local people still regard the species as a serious threat to poultry, so The Peregrine Fund now has a program to provide small chicken cages to local subsistence farmers so that they can protect their young chickens from depredation.

Significant causes of natural mortality are poor weather (rain lasting over several days when nestlings are less than one week old), collapse of nests and infestations of the parasitic bot fly Philornis pici (The Peregrine Fund 2014); Philornis pici causes high mortality in nestling hawks (Hayes et al. 2018) and has also occasionally been recorded infecting adult nesting hawks (Quiroga et al. 2020). Infestation of nestlings by Philornis spp. is prevalent, some years affecting almost 90% of Ridgway’s Hawk nests and the odds of a nestling surviving to fledge decrease dramatically with infestation (Hayes et al. 2018, Bulgarella et al. 2019). Electrocution on power poles is a also a significant threat in urban and suburban areas. In the Punta Cana release area over 200 power poles have been retrofitted to prevent electrocution, a joint effort between The Peregrine Fund and Grupo Puntacana (Dwyer et al. 2019, T. Hayes unpubl. data). Woolaver et al. (2013a) detected a weak but consistent sex ratio bias towards female nestlings, which could give cause for concern in the future. Inbreeding within the small population also poses a threat (Woolaver et al. 2013b).

Conservation actions

Conservation Actions Underway 
Effective protection of the Ridgway’s Hawk population in Los Haitises (currently the largest extant population). Most Ridgway’s Hawk pairs occur within Los Haitises, but this site is poorly protected and evidence suggests that it has been mainly deforested (Dirección Nacional de Parques 1991, Brothers 1997). Additionally, political structure in the Dominican Republic makes lasting changes to park rules and regulations difficult and the park boundary has changed several times, from 208 km2 in 1976 to 1600 km2 in 1992. Currently, Los Haitises is about 600 km2 (Dominican Law: Ley 202-04). Ongoing conservation action in the park is essential for the continued growth of B. ridgwayi populations within its boundaries and should conservation action cease, the ongoing population increased observed may well slow, or even revert to declines.
Improvement of reproductive success through treatment of Ridgway’s Hawk nests to prevent nest fly parasitism of nestlings by Philornis spp. The primary focus of Ridgway’s Hawk nest management is to prevent nestling mortality caused by parasitic nest flies of the genus Philornis. Treatment of nests and/or nestlings has resulted in a 179% increase in the probability that a nestling will successfully fledge into the wild (Hayes et al. 2018). Should nest treatments for Philornis spp. cease however, reproductive rates would likely drop considerably as anywhere between 0.19-0.65 nestlings are common per pair in untreated nests, compared to 1.2-1.65 nestlings per pair in treated nests (T. Hayes in litt. 2020). Intensive research of Ridgway’s Hawk breeding ecology and conservation genetics are part of an ongoing study initiated in 2005, and annual surveys monitor the hawk population within Los Haitises (The Peregrine Fund 2014). Through intensive management of nests in Los Haitises, The Peregrine Fund is increasing productivity of wild pairs from 2 -4 fold (Hayes et al. 2018, T. Hayes unpubl. data). These actions are simultaneously bolstering the wild population of Ridgway’s Hawk in Los Haitises as well as allowing for the removal of some wild nestlings for translocation and release in regions where the species is native, but has been extirpated.
The creation of at least three Ridgway’s Hawk populations outside of Los Haitises. The Ridgway’s Hawk population decline measured by Woolaver from 2005 – 2009 has been reversed and the Ridgway’s Hawk population in Los Haitises is now growing (Woolaver 2011, T. Hayes unpubl. data). In some areas that The Peregrine Fund is working (specifically in Los Limones, Los Haitises NP), the number of Ridgway’s Hawk nesting pairs has almost doubled since 2011. The Ridgway’s Hawk population is increasing in the other areas of the park as well (T. Hayes unpubl. data). The Peregrine Fund has focused their conservation effort on the management of nests in Los Haitises as well as the translocation of wild Ridgway’s Hawk nestlings for reintroduction into areas where the species has been extirpated. Captive breeding programs, while useful in some situations can drain limited resources away from the protection of wild populations. In 2008 and 2009, The Peregrine Fund began translocating nestling Ridgway’s Hawks from Los Haitises to two distinct sites, Loma la Herradura private reserve and Punta Cana (Thorstrom 2008, The Peregrine Fund 2014, McClure et al. 2017). From 2008 – 2012, 20 young hawks were released near the town of Pedro Sanches, Dominican Republic. Releases at this site were discontinued after 2012 because of high mortality due to human persecution. From 2009 – 2019, a total of 130 birds were released at Punta Cana, Dominican Republic of which the majority became independent, no longer relying on provisioned food (The Peregrine Fund 2014). In 2013, released birds in Punta Cana produced the first nestling ever recorded in the region. There were two breeding pairs the following year and the small population increased incrementally to 19 territorial pairs and 17 wild young fledged in 2019. Two additional nestlings were fostered from destroyed nests in Los Haitises to nests in Punta Cana for a total of 19 young hawks fledged in the wild in Punta Cana in 2019. As of 2019, 49 wild young have fledged in Punta Cana from wild nests (T. Hayes unpubl. data). In 2019, The Peregrine Fund began releasing Ridgway’s Hawks in Aniana Vargas National Park. This small park was created in 2009 and is approximately 130 km2. Habitat in this area is recovering from intensive agriculture and has undergone changes in recent decades to less intensive farming methods, primarily shade-covered cacao plantations.
Education campaign to spread awareness of the ecological and economic benefits of Ridgway’s Hawk and to assist local people in the protection of their young chickens from depredation by hawks. A benefit of management of Ridgway’s Hawk populations within Los Haitises is that local individuals are able to carry out the fieldwork. This means that people in communities around the hawk population are invested in the conservation of the species. In 2005 by The Peregrine Fund initiated a publicity campaign to raise awareness of the Ridgway’s Hawk within local communities near hawk populations (Woolaver 2006) and environmental education continues in Los Haitises and in areas where the hawks have been reintroduced. In order to reduce direct human-caused Ridgway's Hawk mortality, The Peregrine Fund began an intensive environmental education program in Dominican Republic in 2013. In the first two years, the environmental education program engaged with over 1,168 individuals in communities around Punta Cana (The Peregrine Fund 2014). The Peregrine Fund is currently working with over 50 communities around established Ridgway's Hawk territories and areas where the Ridgway’s Hawk has been reintroduced, and have reached over 13,500 people through direct efforts since the start of the program. Environmental education activities have been ongoing, and include community and door-to-door visits, public presentations, school visits, celebrations of Ridgway's Hawk Day, as well as teacher training workshops revolved around environmental education and the conservation of raptors. Additionally, other project partners including Propagas Foundation, Grupo Puntacana Foundation, and Zoodom (Santo Domingo Zoo) have all taken an active role in increasing awareness of Ridgway’s Hawk (Marta Curti pers. comm.). Local populations must continue to be involved in conservation projects to prevent reversion to practices that result in high B. ridgwayi mortality.
CITES Appendix II. The risk of electrocution on power poles is high for Ridgway’s Hawks in urban and suburban areas within the Dominican Republic. In 2014, 33% of young hawks in the Punta Cana region were electrocuted. The Peregrine Fund and Grupo Punta Cana have been working together to retrofit over 200 power poles to prevent electrocutions of Ridgway’s Hawk as well as other wildlife. Retrofitting of power poles to prevent electrocution is an ongoing effort and has dramatically improved survival in the Punta Cana region (in 2017 only one of 25 released hawks was electrocuted [Dwyer et al. 2019, T. Hayes unpubl. data]).

Conservation Actions Proposed 
Ensure the de facto protection of remaining habitat in Los Haitises National Park. Continue and expand education and awareness campaigns to reduce direct persecution, including campaigning for a 'Ridgway's Hawk Day' to become a national holiday in the Dominican Republic (The Peregrine Fund 2014). Continue monitoring, nest management, and banding work (The Peregrine Fund 2014). Survey remaining forest fragments adjacent to Los Haitises National Park, as well as historical sites that have not experienced significant habitat loss. Assess potential sites for future relocation to establish additional populations within secure habitat. Ensure that translocated nestlings are genetically diverse (Woolaver et al. 2013b). Evaluate the threat posed by power lines and retrofit them where necessary in potential release areas (The Peregrine Fund 2014). Continue research into methods to reduce Philornis pici infestations. Recent sightings of Ridgway’s Hawk in Haiti reopen the possibility that conservation efforts in these locations may be warranted.

Identification

36-41 cm. Medium-sized, compact hawk. Adult has brown-grey upperparts, greyish barred underparts with reddish-brown wash, rufous thighs and black-and-white barred tail. White crescent-shaped wing panels or "windows" visible during flight are diagnostic. Male slightly smaller (330-350g) than female (360-420g). Male is greyer than female and has rufous carpal area (paler rufous in female). Female also paler below and more barred. Immature has buffy white underparts with grey and brown streaks, and less well marked tail. Similar spp. Red-tailed Hawk B. jamaicensis is larger and adults have reddish tail. Voice Shrill calls and squeals.

Acknowledgements

Text account compilers
Wheatley, H., Everest, J.

Contributors
Brocca, J.L., Hayes, T., Keith, A., Latta, S., Thorstrom, R., Woolaver, L., Westrip, J.R.S., Taylor, J., Sharpe, C.J., Calvert, R., Bird, J., Ashpole, J, Benstead, P., Butchart, S., Isherwood, I., Symes, A. & Wege, D.


Recommended citation
BirdLife International (2022) Species factsheet: Buteo ridgwayi. Downloaded from http://www.birdlife.org on 03/07/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 03/07/2022.