Winter Surveys of Birds in Cuba

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Winter Surveys of Birds in Cuba

The winter of 1996/97 marked the 9th year of our involvement in ornithological research in Cuba. 1997/98 will be our 10th!

Cuba comprises approximately half of all the land in the Caribbean. It is a tropical island with a rich avifauna and diverse flora. Although it has a growing network of reserves and national parks, ranching, logging, and agriculture have contributed greatly to deforestation and forest fragmentation over the past 100 years. In spite of this, Cuba has one of the lowest rates of deforestation in the Caribbean and current forest area is approximately 16.0%. However, the country's economic situation has worsened dramatically in recent years. As a result, forested areas in Cuba face renewed threats from agricultural expansion, mining, tourism, and wood cutting as the government attempts to rescue the economy. Regrettably, much of this activity proceeds without proper environmental review.

Cuba's ornithological tradition dates back to the 1870s with the pioneering work of Juan Gundlach who wrote the first major work on the island's birds, Ornitología Cubana, and whose name is immortalized in the scientific and common names of several species, including Gundlach's Hawk and Cuban Vireo. In the 20th century, Thomas Barbour, James Bond, Orlando Garrido, Florentino García Montaña, and others have added to the knowledge of the distribution, taxonomy and biology of Cuban birds. In total, 355 species have been recorded, including 23 endemics (those that occur nowhere else in the world), and 165 species that breed in North America and winter or pass through Cuba during migration ("neotropical migrants"). Despite this history of exploration and study, Cuba is still "ornithologically young" in comparison to North America. Details of the breeding biology of many resident species remain unknown and quantitative data on the distribution and abundance of migrant species are scarce.

We might not have initiated bird studies in Cuba without Graeme Gibson, noted Canadian author and avid bird watcher, whose travels in Cuba put him in touch with a number of Cuban ornithologists. Graeme was struck not only by the competence and enthusiasm of the Cuban scientists, but also by their isolation from their North American counterparts and their lack of equipment and other resources that we take for granted. He decided to play an active role in bringing North American and Cuban ornithologists together. Due to the US trade embargo with Cuba and other restrictions that make dealing with Cuba difficult for American institutions, Canadian organizations were in an ideal situation to participate in cooperative programs with the Cubans.

The result of Graeme's match-making efforts was a cooperative project during the winters of 1988 and 1989 to provide training in field ornithology techniques and equipment to Cuban ornithologists and to investigate the possibility of conducting more in-depth research on the status on neotropical migrants wintering in Cuba. The cooperating organizations were the Long Point Bird Observatory (later Bird Studies Canada), the Canadian Wildlife Service, and the Cuban Institute of Ecology and Systematics. Work was conducted at sites in the vicinity of the Zapata Swamp, the most important wetland in the Caribbean. Incredibly, it was the first work of its kind conducted in Cuba in over 30 years.

The pilot project was highly successful at bringing Canadian and Cuban scientists together. Many professional relationships were forged and the results suggested that at least the Zapata area was very rich in over-wintering forest birds. The project was also timely in that it coincided with a marked upsurge in concern for neotropical migrants, particularly forest-dwelling landbirds breeding in eastern North America. Results of population monitoring programs such as BSC's Migration Monitoring Programs and the Breeding Bird Survey had demonstrated that a number of neotropical migrants were in decline, some seriously. Migrants pose complex conservation problems since their populations can be impacted on their breeding grounds, wintering grounds, and during migration. Many researchers realized that there was much to learn about the status of neotropical migrants on the wintering grounds and the factors affecting their populations there. Our cooperative program was the only one that showed promise for gathering data in Cuba, the spot likely to be the most important wintering area in the Caribbean.

In 1991, we initiated a multi-year project to describe the abundance and habitat use of neotropical migrant and resident landbirds at sites throughout Cuba. Our goals were to provide quantitative information that could be compared with data on the status of migrants elsewhere in the Caribbean and Latin America and to enhance conservation efforts in Cuba by documenting the avifauna of sites that were either designated, or under consideration, as protected areas.

The Field Study

Our work has been conducted during the winter at 18 sites, six in each of three areas: the Zapata Swamp, Mil Cumbres in the western mountains, and Cayo Coco. The habitats surveyed included dry and moist semideciduous forest in Zapata and on Cayo Coco, dry coastal scrub on Cayo Coco, sub-coastal mangrove forest on Cayo Coco, and montane semideciduous and montane pine forest in Mil Cumbres.

Most sites were very rich in neotropical migrants. Importantly though, we noted that there were strong regional differences. Overall, we detected 82 bird species of which 32 (39%) were neotropical migrants. Based on banding data, the proportion of migrant individuals ranged from 17.1 to 53.0%. On average, Cayo Coco and Zapata had higher proportions of migrant individuals than Mil Cumbres. The proportion of migrant species was also higher on Cayo Coco and in Zapata than in Mil Cumbres. Capture rates and numbers of species of both residents and migrants were higher on Cayo Coco than in the other two regions. Point counts produced similar results, except that they indicated higher detection rates of residents and higher numbers of resident species at Mil Cumbres than elsewhere. Migrants were poorly represented in point counts.

Lowland, moist semideciduous forest was the most important of the habitats surveyed for neotropical migrants. Although we surveyed only one mangrove site (on Cayo Coco), it too was particularly rich in migrants. In Mil Cumbres, pine forest supported greater numbers of migrants and residents than semideciduous forest. Within regions, dry forest types supported fewer migrants than moist forest types. In general, banding data suggested that the numbers of migrants and residents were correlated with each other. Sites that supported good numbers of residents also supported many migrants.

The five most frequently encountered migrant species were Gray Catbird, Black-throated Blue Warbler, Black-and-white Warbler, American Redstart, and Ovenbird, all being found in at least 75% of the areas surveyed. All but the Ovenbird were most common on Cayo Coco and least abundant in Mil Cumbres. Ovenbirds were slightly more common in Mil Cumbres than in Zapata. These species, like many others, were more common in particular regions or exhibited preferences for particular habitats within regions. For example, on Cayo Coco, Gray Catbirds were more common in moist, semideciduous forest than in scrub or mangrove. In Mil Cumbres, Black-throated Blue Warblers were more common in pine than in semideciduous forest, while on Cayo Coco, they were more common in coastal scrub.

We also demonstrated that certain species, such as American Redstart and Black-throated Blue Warbler, exhibited differing ratios of male to female individuals in not only different forest types, but also in different regions in the same forest type. In addition, a statistical analysis correlating vegetation structure with mist net captures suggested that resident species occupy a broader spectrum of vegetation structure types than migrants, which as a group favoured sites with structure typical of secondary forest.

This study is the most extensive survey of neotropical migrant and resident birds yet undertaken in Cuba. We found that Cuba is an important wintering area supporting large numbers of migrant individuals and species. The surveys provided many new records for species on a regional and national scale, and increased our understanding of the winter status of several neotropical migrants, notably Swainson's Warbler. Cuba apparently supports more migrant individuals and species than other islands in the Caribbean. Compared to the Yucatán Peninsula of Mexico and Belize, Cuba supports fewer migrant species, but they account for a greater proportion of all species present and a lower proportion of individuals.

Our surveys sampled forest habitats that account for a large proportion of the forest cover in the regions surveyed and remaining in Cuba. Lowland moist semideciduous forest was historically the most widespread type in Cuba, and in the West Indies in general. Today, it constitutes an important habitat for wintering migrants and residents. The fact that we observed strong regional differences in abundance of residents and migrants is important for conservation planning since it suggests that extrapolation of data from one area to another is risky, especially on large islands. For many islands in the Caribbean, abundance data exists from only a limited number of sites, but these data may not provide enough information to accurately determine how common particular migrant or resident species are likely to be at other sites on the same island. Sexual habitat segregation has been described from other localities in Latin America and the Caribbean. Certainly, it suggests that conservation of one habitat may not be sufficient to protect a species if the sexes tend to inhabit different types. Our work suggests that the problem is even more complex, since habitat segregation within a given forest type also varied among regions.

It was an important finding of the study that banding and point count results sometimes differed. Resident species are often larger and more vocal than migrants and better detected by counts, whereas migrants are better detected by capture in mist nets. Our results suggest that the best results are obtained by using a combination of both techniques intensively and in concert with each other.

Thanks are due to the many people who participated in the hours of planning, fieldwork, and data analysis that went into the project. Special thanks to our primary funders: the Canadian Wildlife Service Latin American Program and the Canadian Nature Federation.

Readers interested in learning more about our work in Cuba should consult:

Kirkconnell, A., G.E. Wallace, and O.H. Garrido. 1996. Notes on the status and distribution of the Swainson's Warbler in Cuba. Wilson Bull. 108:175-178.

Wallace, G.E., H. González Alonso, M.K. McNicholl, D. Rodríguez Batista, R. Oviedo Prieto, A. Llanes Sosa, B. Sánchez Oria, and E.A.H. Wallace. 1996. Winter surveys of forest-dwelling neotropical migrant and resident birds in three regions of Cuba. Condor 98:745-768.

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