Birds

Abstract:

Of 123 adult and semi-adult Little Herons Butorides striatus examined from the South Caribbean Islands of Aruba, Curaçao, and Bonaire, either as study-skins, observed in the field or shown on colourslides, 115 (93%) were of the red-necked North American and Caribbean virescens subspecies type, whereas 7 (6%) showed characters intermediate between virescens and the continental South American striatus subspecies type. Once (1%) an apparently phenotypically "pure" B. s. striatus was observed (3 Oct. 1979, Bonaire). The South Caribbean Island's breeding birds should be namend Butorides striatus maculatus rather than Ardeola striata striata as listed by PAYNE (1979). Three specimens (19%) of 16 measured proved to be long-winged migrants from North America, B. s. virescens (17 Nov. 1951, 27 Nov. 1951, 21 Oct. 1954). 

About 210 resident and migratory bird species are found on the island of Bonaire. More than half of these species are landbirds. Some of the landbirds are endemic subspecies. Despite its small area, Birdlife International designated five Important Bird Areas (IBAs) on Bonaire. This manual is a working tool for STINAPA employees and volunteers doing landbird surveys on Bonaire.

1) The monitoring program covers the areas considered potential habitat for feeding, nesting, and roosting of the selected species of landbirds on Bonaire. 2) Surveys are conducted at least twice per year (February-March and September-October). About 10 days are needed per sampling period. 3) Morning counts start after sunrise and stop at 10:00 hours. Afternoon counts start at 16:00 hours and stop before sunset. 4) At least two observers are needed for the collection of count and supplementary data related to habitat, food, disturbance, and other factors that may affect species detection and abundance at sampling units (fixed on-road and off-road points). 5) Additional information are collected about uncommon observations, such as large flocks in roosting areas, nesting activity, the presence of predators, and any other observation that may be of interest for research, monitoring, and management purposes. The location of these observations is recorded using GPS units. Date, time, and additional comments are also recorded. When possible photos are taken to provide complete documentation for future reference and consultation as needed. 6) Weather conditions are recorded as part of standard data collection. 7) Just like any other activity conducted by STINAPA Bonaire, human safety is always considered a priority over the completion of survey activities.

There are 330 parrot species worldwide, of which a third is threatened with extinction. The Yellow-shouldered Amazon (Amazona Barbadensis) is a parrot species found in northern Venezuela and on the Caribbean islands Margarita, La Blanquilla and Bonaire. The total population size is estimated at 3.000-10.000 parrots, which has led the IUCN to classify its global condition as vulnerable. The population size on Bonaire is estimated at 800 parrots.
The goal of this study was to examine both the threats A. Barbadensis is facing on Bonaire and the opportunities to resolve them. Three methods were used during this process. First a literature study was conducted regarding the population dynamics of A. Barbadensis on Bonaire, resulting in a quantification of the different population parameters and environmental factors, affecting the parrot population. Secondly, a population dynamics simulation model was used to determine the sensitivity to changes in these environmental factors and population parameters. The model was finally used to analyze the impact of several scenarios on the population size over a period of 200 years.
The most important factor constraining the growth of the parrot population on Bonaire, is the limited number of nest sites in both trees and cliffs. Nest site limitation is inferred from the fact that only 21.5% of the population breeds annually. The low supply of tree cavities is caused by the exotic and invasive goats and donkeys who are responsible for the degraded state of the vegetation since their introduction in the 16th century. An eradication program would allow the ecosystem to restore to its natural balance. A. Barbadensis would benefit by increased survival in all life stages due to a substantial increase in food resources, which will prevent the parrots from having to visit the hazardous urban areas, and by an increase in the number of nest sites. The scenario exploring the effects of this drastic measure reveals a population growth to several thousands of parrots.
It must be noted however that this scenario does not include any density dependant factors that would eventually limit the growth rate.
The population is most sensitive to changes in juvenile and adult survival, which corresponds with the r/K selection theory and another theoretical viability study regarding A. Barbadensis. Conservation initiatives should therefore focus on increasing their survival as it will be more beneficial to the persistence of the species than improving upon chick survival and female reproductivity.
The exact effects of climatic stochasticity on parrots are not well known. This study assumed the climate affected both survival in all life stages as well as reproduction. Changes in the impact of the climatic stochasticity showed a high sensitivity, which emphasizes the need for a better understanding of the impact the climate has on the survival and reproductive parameters of A. Barbadensis. The parrot population on Bonaire can be considered as viable as the current conditions will not lead to extinction, nor will any of the other scenarios examined in this study. However, the reality might consist of a combination of these scenarios, affecting the parrot population more severely. It is therefore recommended, as a bare minimum conservational approach, to maintain the annual count of the population size in order to readily notice a decline in population size, enabling counter measures to be taken accordingly.

Management Recommendations:

• The boundaries of the WSNP should be expended to include all the salinas included in this survey. This expansion will not only benefit the waterbirds but every other native species of flora and fauna as well.
• Pursue the designation of Salina Frans as a Ramsar site for Bonaire, given its importance as a habitat for both terrestrial and waterbirds.
• Keep collecting data for long term monitoring programs. It is fundamental for the proper management of our natural resources.
• Provide more training for the staff involved in the counts.
• Install permanent depth gauges in all the salt flats being monitored.
• Conduct more scientific research for a better understanding of the ecological functions of the salinas as a habitat for water birds
• As resources or time become available, start a monitoring program for the nesting seasons of our resident waterbirds. 

Abstract:

A preliminary inventory is given of key terrestrial nature values of Bonaire in order to determine their occurrence in relation to areas designated as “nature” and “open landscape”, according to the Spatial development plan of Bonaire. This was based on a literature study and supplemented by expert advice.

In 2010 a spatial development plan was written in order to determine the spatial policy and regulation for the future development of Bonaire. The island was partitioned into areas for different uses such as agriculture and recreation. Two specific designations are “nature” and “open landscape”. The occurrence of nature values within these areas remained unclear. This makes implementation of protective measures based on international treaties and island legislation problematic. An inventory of the occurrence of these values should help facilitate more effective implementation of these protective measures. In the present study key nature values are determined, both in terms of protected species and essential habitat (e.g. caves). 

From the literature study it became apparent that data on the occurrence of most of the priority species of flora and fauna, is limited and scattered, especially with respect to “open landscape” and “nature” outside parks. Therefore, only a preliminary inventory is provided showing the general distribution of nature values across the entire island, as linked to various habitat types. An exact distribution of the different nature values was not possible at this time, but extrapolation from areas of known occurrence into other areas of similar habitat type was used to show the occurrence of overlapping distributions of nature values within the designated areas of “nature” and “open landscape”. The number of overlapping distributions of nature values may contribute to setting conservation priorities.

From the results it can be concluded that the areas of “open landscape” and “nature” (outside the national parks) seem to harbour unique and critical nature values. These areas are not actively managed or protected as national parks. The “open landscape” of Bolivia possibly harbours a few rare plant species (unique), an important population of critical key columnar cacti and at least two columnar cactus-pollinating bat species. The “open landscape” of Washikemba/Bakuna harbours key mangrove species that only have another main location at Lac Bay (national park). The “nature” area of Terrace Landscape Middle Bonaire seems to harbour a concentration of unique (e.g. Tillandsia balbisiana) and rare plant species (e.g. Krugiodendron ferreum etc.) and four bat species. The same is the case for Lima (e.g. Sabal palm, Maytenus versluysii and three bat species) while in Southern Bonaire key mangrove species also still occur. Table 1 shows which nature values are found or expected to occur within each “open landscape” and “nature” (outside national parks) area.

It can be concluded that outside the current parks, the main regions that harbour a concentration of key nature values are Terrace Landscape Middle Bonaire/Sta. Barbara, Bolivia, Washikemba/Bakuna and Lima. Terrace Landscape Middle Bonaire is designated as “nature” area, while Washikemba/Bakuna and Bolivia are in part designated as “open landscape”. Lima has both “nature” and “open landscape” designations. Sta. Barbara is designated for other uses, but the present review shows that the occurrence of several significant nature values is likely within this area.

Additionally, based on the preliminary inventory, the combination of apparent concentrations of rare plants, occurrence of critical bat species and the high probability of corridor values show that the areas of Terrace Landscape Middle Bonaire/Sta. Barbara and Lima are important areas concerning conservation and further research. The areas of Bolivia and Washikemba/Bakuna follow closely.

To be able to implement the necessary protective measures within these areas, it is recommended that more extensive research through fieldwork is done, in order to obtain a complete inventory of the different nature values found on Bonaire, not only in the areas of “nature” and “open landscape” but also in areas with other designations. Additionally, it is recommended to assess the list of vulnerable and endangered species (‘Informatieblad beschermde dier- en plantensoorten Bonaire’) as certain species that may be of importance to Bonaire are not included.

When executing a complete and extensive inventory of Bonaire it would be of value to also determine the ecological conditions needed for the different species to survive. Based on the ecological conditions necessary for their life functions, it may be possible to pinpoint those areas of main ecological importance per species. A complete inventory of the nature values on the island can contribute to better management of nature values (e.g. determining the distribution of caves and the distribution, health status and diversity of keystone cacti species for better management of bat populations). It is also recommended to determine areas with high potential for the occurrence of rare or relict species and which areas harbour high corridor values.

Management Recommendations:

For future research it is recommended to execute a complete and extensive inventory of Bonaire, through fieldwork, in order to implement the necessary protective measures to ensure the conservation of these nature values. The present study shows that the areas of WNSP/Brasil, Terrace Landscape Middle Bonaire, Lima and Bolivia may be of priority as these areas seem to harbour a concentration of unique and critical plants.

Present studies shows that key nature values may occur in areas with a different designation than “nature” or “open landscape”. For future research it is recommended not to limit inventory research to the areas of “nature” and “open landscape”, but to include other areas with different designations.

In the present study the nature values chosen were based on the list of vulnerable and endangered species (Informatieblad beschermde dier- en plantensoorten Bonaire). During the study several species were added based on expert knowledge. The list used therefore seems to be limited. For future research it is recommended to assess if there are other nature values that are important to Bonaire that should be included on the list (e.g. Clusia sp, Ammodramus savannarum).

A complete inventory of the nature values on the island can contribute to the better management of nature values. A good example is the management of Bonaire’s bat population. In order to define the priority areas to maintain for the management of the different bats on Bonaire it is essential to obtain a detailed inventory of the different caves that these species use as habitat.

Additionally for the nectar-feeding bats it is crucial to map the occurrence of the different candle cacti on which they feed. The nectar-feeding bats are the critical pollinators of the three candle cacti (Petit, 2001). As already mentioned these cacti are key species on the island as they provide food for several species of animals during the dry season, when many other plant species are non-productive (Petit, 2001). Research on the distribution, health status and diversity of candle cacti on Bonaire is recommended in order to pinpoint priority areas for nectar- feeding bats. The cactus populations are threatened severely by feral livestock (goats, donkeys) which remove the bark of the mature trees, thereby threatening the food supply for frugivores and nectarivores. From our analysis open land areas of Bolivia would seem to possess large cactus populations of vital interest to conservation of endangered bird species on an island-wide scale.

When executing a complete and extensive inventory of Bonaire it would be of value to determine the ecological conditions and various habitats needed for the different species to survive. Based on the ecological conditions necessary for their life functions it may be possible to pinpoint those areas of principal ecological importance per species.

It is necessary to identify those areas with a high potential for the concentration of nature values rare species or relict vegetation species in order to secure the survival of these species and to be able to implement the necessary protective measurements. Such areas for instance are the open land and nature sections of Lima, Terrace Landscape Middle Bonaire (nature) and Bolivia (open). For future research it is recommended to determine those areas with high corridor values for the implementation of ecological corridors and buffer zones on Bonaire. 

Abstract:

In October 2011 an expedition took place to the Saba Bank, on board of the ship the Caribbean Explorer II. Main aim of the expedition was collecting data on underwater fauna and coral reefs. Apart from that data were collected on nutrients, water flow, sponges and seabirds and marine mammals. Data on the last group were collected by deploying acoustic data loggers, and by means of visual surveys. These visual surveys were conducted whenever the other activities permitted it. This cruise report presents an brief overview of the results obtained during the October 2011 survey. It contains a short day to day report, a full list of all birds, mammals and particular pieces of floating matter seen, and a brief presentation of the results. Furthermore the report contains a brief account of observed birds on Sint Maarten, since published accounts on the birdlife of the island are scarce.

Findings

Seabirds

• The seabirds most often spotted were the Brown Booby and the Magnificent Frigatebird.
• No marine mammals were observed.
• Red-Billed Tropicbirds were primarily spotted near the shore of Saba.

Birds on Sint Maarten

The first ever records of the following birds were made during this expedition:

• Cinnamon Teal (possibility of a hybrid cannot be excluded).
• Marbled Godwit (flying over the Great Salt Pond).
• A Merlin was seen hunting amongst Cliff Swallows and Barn Swallows.
• Three Ospreys were recorded.
• Breeding Caribbean Coots or adults with chicks were seen at several small ponds and in the salines.

Most Common (sighted>10)

• Cattle Egret (Bubulcus ibis)
• Snowy Egret (Egretta thula)
• Magnificent Frigatebird (Fregata magnificens)
• Brown Pelican (Pelecanus occidentalis)
• Black-necked Stilt (Himantopus mexicanus)
• Spotted Sandpiper (Actitis macularius)
• Carib Grackle (Quiscalus lugubris)
• Bananaquit (Coereba flaveola)

Least Common (sighted<2)

• Merlin (Falco columbarius)
• American Oystercatcher (Haematopus palliatus)
• Wilson's Plover (Charadrius wilsonia)
• Short-billed (Dowitcher Limnodromus griseus)
• Wilson's Snipe (Gallinago delicata)
• Marbled Godwit (Limosa fedoa)
• Whimbrel (Numenius phaeopus)
• Solitary Sandpiper (Tringa solitaria)
• Lesser Black-backed Gull (Larus fuscus)
• Cabot's Tern (Thalasseus acuflavidus)
• Eurasian Collared Dove (Streptopelia decaocto)
• Rose-ringed Parakeet (Psittacula krameri)
• Yellow-billed Cuckoo (Coccyzus americanus)
• Green-throated Carib (Eulampis holosericeus)
• Antillean Crested Hummingbird (Orthorhyncus cristatus)
• Northern Parula (Parula americana)
• Caribbean Elaenia (Elaenia martinica)
• Pearly-eyed Thrasher (Margarops fuscatus)
• House Sparrow (Passer domesticus)
• Northern Parula (Parula americana)
• Blackpoll Warbler (Dendroica striata)
• Prothonotary Warbler (Protonotaria citrea)

Notes:

The vessel that was used during this survey was not well suited for dedicated seabird and cetacean surveys. However, the gathered data fits in well with the seasonal pattern in observed seabird species and densities described for Guadeloupe for the same time period (distinct dip from August to October). According to Debrot et al, there are few records of cetaceans in October.

Abstract:

The Important Bird Area (IBA) programme is an initiative of BirdLife International aimed at identifying, monitoring and protecting a network of key sites for the conservation of the world's birds. On the islands, Bonaire, Sint Eustatius (Statia) and Saba, nine IBAs have been designated in recent years. Prior to this study the boundaries of these areas were imprecisely defined and the specific ecological values of these areas were poorly documented and did not provide sufficient footing for further legal protection. In this report we compile available information, add recently collected field data and precisely define boundaries based on ecological and planning criteria so as to furnish the level of documentation sufficient to allow further legal designation and protection by island governments.

In this report we specifically:

• document the most important ecological values represented in each IBA
• define exact boundaries based on ecological and planning criteria and pinpoint core areas that can be distinguished for each IBA 
• discuss the IBA’s spatial context within development and/or land-use plans
• identify potential factors and developments that threaten the long-term spatial and ecological integrity of each IBA
• determine which measures are needed to maintain the spatial and ecological integrity of each IBA.

On Saba one IBA is identified: Saba coastline IBA (AN 006). The 2,145 ha IBA of Saba lacks any form of legal designation as a protected area. Its value is especially based on breeding seabirds, most importantly the Red-billed Tropicbird and the Audubon’s Shearwater. In addition to legal designation, measures needed to protect the values of this IBA include eradication or control of predators such as cats and rats, and management of the garbage dump to limit the number of these predators. On Saba no gaps in IBA coverage are identified.

On Sint Eustatius two IBAs are identified: Boven (AN 007) and The Quill (AN 008). In contrast to Saba, the two IBAs of St. Eustatius enjoy almost full legal designation as protected park areas. Based on our findings we propose an extension of the 1,106 ha Boven IBA to include Signal Hill for its concentration of nesting Red-billed Tropicbirds. The problems caused by cats and rats are much less acute on Statia than on Saba. The value of the 472 ha Quill IBA is largely based on the resident breeding landbirds it supports. Key threats include goats and possibly feral chickens.

On Bonaire six IBAs are identified: Washington-Slagbaai National Park (AN 009), Dos Pos (AN 010), Washikemba-Fontein-Onima (AN 011), Klein Bonaire (AN 012), Lac Bay (AN 013), and Pekelmeer Saltworks (AN 014). The IBAs are designated as “nature” or “open landscape” in the Nature Policy Plan Bonaire spatial plan, thus enjoying protection. 

Washington-Slagbaai National Park (AN 009). (Size: 7,529 ha.) 
The Slagbaai IBA covers a diversity of habitats ranging from coastal lagoons to vegetated hillsides. Key values include its habitat value for Yellow-shouldered Amazon, nesting terns and foraging (West-Indian) Flamingos. Most of the area is legally protected either as an island park or with Ramsar status and actively managed. Key threats include overgrazing by feral goats and pigs. Poaching of the Yellow-shouldered Amazon is also a significant problem. Disturbance of tern colonies also occurs due to inappropriate routing of vehicles close to the important nesting island in the Slagbaai lagoon.

Dos Pos (AN 010) (Size: 293 ha.)
Dos Pos IBA is relatively small and largely has no legal protected status. It is an important freshwater site and is both of importance to resident species of which Yellow-shouldered Amazon is the most threatened worldwide. 

Washikemba-Fontein-Onima (AN 011) (Size: 6,286 ha.)
The Washikemba-Fontein-Onima IBA includes critical habitat for the Yellow-shouldered Amazon, nesting terns and the Caribbean Coot. About half the area is legally designated as either as “Island Park” or “Protected Landscape” in the Nature Policy Plan Bonaire. 

Klein Bonaire (AN 012) (Size: 2,052 ha.)
The Klein Bonaire IBA enjoys full legal protection being designated as a local conservation area and as an internationally recognized Ramsar wetland. The island and surrounding reef are protected within the Bonaire National Marine Park. It is principally of value as a tern nesting island. The woodlands are recovering since complete removal of goats from the island.

Lac Bay (AN 013) (Size: 2,117 ha.)
The Lac Bay IBA enjoys legal designation both as an island conservation area and as international Ramsar wetland site. The mangroves and salt flats are of local significance to nesting terns and hold a breeding population of the Reddish Egret (IUCN-status Near-Threatened).

Pekelmeer Saltworks (AN 014) (Size 6,197 ha.)
The Pekelmeer Saltworks IBA covers about one fifth of the island of Bonaire. Only the 55 ha “Flamingo Sanctuary” and the Pekelmeer enjoy island legal protected status and Ramsar wetland status, while most of the area is used as saliña by the Cargill company. Key IBA values in this area include the nesting colony of the Caribbean Flamingo, and nesting colonies of various tern species. The construction of isolated islands that will not be subject to industrial traffic along the dikes of the managed ponds should provide suitable nesting habitat for recovery of tern nesting in this area of the island. The Laughing Gull population of Bonaire is expanding largely due to the open landfill. This species predates on tern nests and should be controlled if it continues to expand in numbers.

All in all 18 trigger species occur in the nine IBAs in the Caribbean Netherlands. The IBAs on the Leeward islands of Saba and Sint Eustatius host ten and eleven species respectively. Saba is important for the breeding seabirds Audubon’s Shearwater and Red-billed Tropicbird, species with a high conservation priority. The Saba Coastline IBA is the only IBA in the Caribbean Netherlands that qualifies for Audubon’s Shearwater. Saba’s IBA qualifies for another seven species which are all year-round residents with a restricted world’s breeding distribution. St. Eustatius is important for the breeding seabird Red-billed Tropicbird, as well as another eight species: Bridled Quail-dove, hummingbirds and songbirds with a restricted range. The IBAs on the Leeward island of Bonaire host ten trigger species. Some of Bonaire’s IBAs are important for breeding seabird species with a high conservation priority like Royal, Sandwich, Common and Least Tern. Furthermore Bonaire’s IBAs are important for a number of species with a restricted range, of which Caribbean Coot and Yellow-shouldered Amazon have a high conservation priority.

Management Recommendations

On Bonaire several areas are identified that host IBA key species or other ecological valuable bird species and currently are not designated as IBA: 1) Ponds north of Dos Pos; 2) Ponds east of Kralendijk; 3) Urban parrot roosts; 4) Seru Largu. 

This report is part of the Wageningen University BO research program (BO-11-011.05-016) and was financed by the Ministry of Economic Affairs (EZ) under project number 4308701005.

Management Recommendations:

• Include all the area of Salina Goto and salina Frans inside the borders of WSNP. This expansion will not only benefit the waterbirds but every other native species of flora and fauna as well.
• Pursue the designation of Salina Frans as a Ramsar site for Bonaire.
• Keep collecting data for the long term monitoring programs. It is fundamental for the proper management of our natural resources.
• Provide more training for the staff and volunteers involved in the counts.
• Install permanent depth gauges in all the salinas being monitored.
• Conduct more scientific research for a better understanding of the ecological functions of the salinas as a habitat for water birds
• As resources or time become available, start a monitoring program for the nesting seasons of our resident waterbirds.
• Spread out monitoring areas to include the Salinas in Central and South of Bonaire.