Neotropical Islands Research Articles

Collembola Diversity across Vegetation Types of a Neotropical Island in a River Delta

Springtails, vital for ecosystem assessment, are often overshadowed by taxonomy-focused research, which mostly neglects their ecology and distribution, particularly in the Neotropical Region. The objective of this study was to identify how environmental factors, especially vegetation types, affect the availability of food resources for epiedaphic Collembola and influence their diversity patterns in three vegetation types (riparian forest, mangrove, and restinga) in the Canárias Island, in Delta do Parnaíba Environmental Protection Area, Brazil (APADP). We collected samples along 200 m transects in each vegetation type during the dry and rainy seasons. After, specimens were sorted, counted and identified. Alpha (species richness, Shannon, Simpson, and Pielou indices) and beta diversity (Whittaker index) were analyzed, along with environmental factors’ influence through Redundancy Analysis (RDA). We sampled a total of 5346 specimens, belonging to three orders, eight families, 23 genera, 31 morphospecies, and one nominal species. Species abundance was positively influenced by soil moisture, plant richness, and leaf litter. The riparian forest sheltered a higher species richness and diversity, and its biotic and abiotic factors likely enhanced the food resource availability, including vegetal organic matter, fungi, and bacteria. These results provide the first taxonomic and ecological data on the Collembola fauna in the APADP.

Growth Rings in Nine Tree Species on a Neotropical Island with High Precipitation: Coco Island, Costa Rica

Coco Island, located 530 km off the Pacific coast of Costa Rica, experiences rainfall of over 7000 mm/year. This study aims to explore the distinctiveness of the growth ring boundaries and the dendrochronological potential (DP) of nine tree species found on Coco Island. The distinctiveness was classified into type 1: density variation; type 2: marginal parenchyma; type 3: fiber/parenchyma pattern; type 4: vessel distribution, and type 5: fiber band. Cecropia pittieri and Henriettella fascicularis lacked growth ring boundaries and, therefore, did not present any DP. Growth ring type 1 occurred in Ardisia compressa, Henriettea succosa, Henriettella odorata, and Psychotria cocosensis. Ocotea insularis and Sacoglottis holdridgei exhibited type 5 growth rings, with sufficient distinctiveness. Finally, Eugenia pacifica possessed growth rings of type 3 and type 4, but with limited distinctiveness in the growth ring boundary. In relation to DP, A. compressa, E. pacifica, and P. cocosensis presented low DP; meanwhile, H. succosa, H. odorata, O. insularis, and S. holdridgei demonstrated medium DP. If these species are found in abundance with a diameter exceeding 60 cm, a cross-dating technique like bomb-spike dating is established to confirm the annual growth of the ‘bands’. As these species exhibit some DP, they can be used to establish a chronology spanning 50–130 years, which could be utilized to create climate proxies or derive ecologically and climatically meaningful information. Additionally, the information presented could pave the way for future studies of sites that also have very high rainfall, where trees are presumed to lack annual growth rings.

Where one species leads, another follows: interspecies processions in tropical caterpillars.

One sunny July morning on the Neotropical island of Trinidad, a group of caterpillars, hundreds strong, marched in head-to-tail procession up their host tree. Among them were two morphs: the majority, long-haired and black, and in smaller numbers, a more cryptic short-haired brown morph. Both proceeded up the tree trunk, thoroughly integrated, and indistinguishable from each other in their behavior. At the bifurcations of branches they split into smaller processions, and continued to the very tips of the branches.

Wildlife rehabilitation: A case study of the neo-tropical, opossum Didelphis marsupialis insularis, Allen 1902.

Wildlife rehabilitation facilities in the Caribbean region are limited, yet they can provide relevant information on wild populations. Didelphis marsupialis insularis is a popularly hunted, under-studied, neo-tropical marsupial species that is increasingly being admitted for rehabilitation. The aim of this study was 1. To record the experiences of rehabilitating D. marsupialis insularis in the neo-tropical island of Trinidad and Tobago and 2. To extract and highlight information on the biology of this opossum sub-species. Using admission records, obtained over a roughly four year period, two breeding periods (February to March and August to October) were illustrated. Litter sizes averaged five individuals, with a range of 1 to 8 young. This species was found to be common in urban areas of the country, with dog attacks reported as the major cause for admission. Thus the information recorded by this wildlife rehabilitation facility has provided great insight on the sparsely studied opossum, D. marsupialis insularis.

Multi-scale response of wetland bird assemblages to landscape patterns on a Neotropical island: when wetland type matters more than size

Understanding wetland bird responses to landscape patterns is central for wetland management and bird conservation. This is particularly relevant on islands, where most of the global extinctions have occurred. In this study, we identified landscape patterns in wetlands on Cozumel Island that best explained abundance of birds grouped in 13 trophic guilds at 3 spatial scales (145, 300, and 850 m radius from count points). By using ordination techniques and generalized linear models we found a scale dependent dissimilarity between the use of extensive estuarine and small inland brackish wetlands. At finer spatial scales, abundance of birds in trophic guilds that mainly use estuarine or inland brackish wetlands was associated with the proportion of land cover types of the corresponding wetland type, whereas at the broadest spatial scale, connectivity of such land cover types was more important. Abundance of birds in trophic guilds that do not prefer any particular type of wetland did not show any relationship with landscape diversity nor connectivity of land cover types, but their abundance showed relationships with specific land cover types from both estuarine and inland brackish wetlands as well as with bordering wetland vegetation. We concluded that the presence of continuous extents of land cover types of both extensive estuarine and small inland brackish wetlands are important for the conservation of distinct wetland bird assemblages on Cozumel Island.

Native parasitic nest fly impacts reproductive success of an island‐endemic host

AbstractParasitic nest flies Philornis spp. are a driving force threatening the extinction of bird species endemic to Neotropical islands such as the Galápagos, where introduced Philornis downsi negatively impacts reproductive success of naïve avian hosts. Elsewhere in the Neotropics, such as in the Caribbean region where Philornis nest flies are native, effects of Philornis on host productivity are poorly known. We manipulated parasitism by the native Hispaniolan nest fly Philornis pici on a critically endangered endemic host, Ridgway's hawk Buteo ridgwayi, to study the impact of nest fly myiasis on hawk breeding success with the goal of providing a management option for endangered species until broad‐scale solutions can be found. Our treatment protocol was enough to reduce P. pici abundance by 89% and increase probability of fledging by 179% for treated nestlings. Our results indicate that parasitism by nest flies decreases survival and fledging success of nestling Ridgway's hawks and is a possible factor in the decline of the species. To the best of our knowledge, this work represents the first quantitative evidence of nest fly impact on survival or productivity in a non‐passerine host.

Predation of Birds by Domestic Cats on a Neotropical Island

Predation of Birds by Domestic Cats on a Neotropical Island

Wild birds as pets in the central region of Cuba: Elements for a mitigation strategy

The island of Cuba has the greatest diversity of birds in the Caribbean, and at the same time, a large number of endangered species. Illegal trade is one of major threats in Neotropical islands, because birds are captured for domestic and international illegal market. This study was undertaken with the aim to characterize the domestic market, in which captive wild birds are used as pets in the central region of Cuba. For this, a census and random survey to identify, and describe wild bird richness and abundance in 10 localities of urban and rural environments, was undertaken from August to November 2014, and from June to October 2015. Our results detected that at least 24 species and 973 individuals from six orders and 11 families were captive. The best represented order was Passeriformes (13 species), followed by Accipitriformes (four species). The best-represented families were Thraupidae (3.3 ± 0.33) and Cardinalidae (2.6 ± 0.45). Besides, the localities of Patria (17), Moron (13) and Bolivia (13) in the urban area had the highest richness. The richness of residents (5.80 ± 0.68) was higher than the endemics (1.70 ± 0.30) and migrants (2.70 ± 0.52), while the richness of endemics (2.5 ± 0.29) and residents (7.75 ± 0.63) was higher in urban areas. There were more captive species with Least Concern category (6.20 ± 1.02), but the Endangered category predominated in rural areas (12.5 %). The most common species were Passerina cyanea , Melopyrrha nigra , Tiaris olivaceus and Passerina ciris. A total of 46% of the species were classified with a tendency to decrease, 33.3 % to increase and 20.8 % to stability. The abundance of species with a tendency to decrease (63.4 ± 22.13) was higher than those that tend to stability (14.8 ± 9.9). The actual traffic will lead to species extinction, mainly parrots and raptors, threatening several ecological services. Illegal trade should be addressed as an environmental, economic and social problem. Strategy for controlling this unsustainable trade was proposed.

Aves silvestres como mascotas en la región central de Cuba: Elementos para una estrategia de mitigación

The island of Cuba has the greatest diversity of birds in the Caribbean, and at the same time, a large number of endangered species. Illegal trade is one of major threats in Neotropical islands, because birds are captured for domestic and international illegal market. This study was undertaken with the aim to characterize the domestic market, in which captive wild birds are used as pets in the central region of Cuba. For this, a census and random survey to identify, and describe wild bird richness and abundance in 10 localities of urban and rural environments, was undertaken from August to November 2014, and from June to October 2015. Our results detected that at least 24 species and 973 individuals from six orders and 11 families were captive. The best represented order was Passeriformes (13 species), followed by Accipitriformes (four species). The best-represented families were Thraupidae (3.3 ± 0.33) and Cardinalidae (2.6 ± 0.45). Besides, the localities of Patria (17), Morón (13) and Bolivia (13) in the urban area had the highest richness. The richness of residents (5.80 ± 0.68) was higher than the endemics (1.70 ± 0.30) and migrants (2.70 ± 0.52), while the richness of endemics (2.5 ± 0.29) and residents (7.75 ± 0.63) was higher in urban areas. There were more captive species with Least Concern category (6.20 ± 1.02), but the Endangered category predominated in rural areas (12.5 %). The most common species were Passerina cyanea, Melopyrrha nigra, Tiaris olivaceus and Passerina ciris. A total of 46 % of the species were classified with a tendency to decrease, 33.3 % to increase and 20.8 % to stability. The abundance of species with a tendency to decrease (63.4 ± 22.13) was higher than those that tend to stability (14.8 ± 9.9). The actual traffic will lead to species extinction, mainly parrots and raptors, threatening several ecological services. Illegal trade should be addressed as an environmental, economic and social problem. Strategy for controlling this unsustainable trade was proposed.

Hearing diversity in moths confronting a neotropical bat assemblage.

The tympanal ear is an evolutionary acquisition which helps moths survive predation from bats. The greater diversity of bats and echolocation strategies in the Neotropics compared with temperate zones would be expected to impose different sensory requirements on the neotropical moths. However, even given some variability among moth assemblages, the frequencies of best hearing of moths from different climate zones studied to date have been roughly the same: between 20 and 60kHz. We have analyzed the auditory characteristics of tympanate moths from Cuba, a neotropical island with high levels of bat diversity and a high incidence of echolocation frequencies above those commonly at the upper limit of moths' hearing sensitivity. Moths of the superfamilies Noctuoidea, Geometroidea and Pyraloidea were examined. Audiograms were determined by non-invasively measuring distortion-product otoacoustic emissions. We also quantified the frequency spectrum of the echolocation sounds to which this moth community is exposed. The hearing ranges of moths in our study showed best frequencies between 36 and 94kHz. High sensitivity to frequencies above 50kHz suggests that the auditory sensitivity of moths is suited to the sounds used by sympatric echolocating bat fauna. Biodiversity characterizes predators and prey in the Neotropics, but the bat-moth acoustic interaction keeps spectrally matched.

Man-made environments relationships with island raptors: endemics do not cope with habitat changes, the case of the island of Cuba

Several studies conducted in neotropical islands have found that the intensity of human activity has altered the original structure and richness of bird communities, strongly affecting endemic species. Despite these effects, studies are limited, and lacking for raptors, in contrast to temperate and continental regions. During breeding and non-breeding seasons of 2012, roadside surveys and point counts were conducted in natural and human-transformed areas of the island of Cuba to determine whether or not raptors from an island show a pattern of ecological response to human activity similar to those observed in continental studies. Raptors showed strong variation in relation to habitat transformations, with lower richness, abundance, and density in the more extensively transformed areas. A total of 11 species was recorded, mostly in natural areas. Similar numbers of species were observed in coastal vegetation and cattle pasture habitat types within each zone. Nine species were detected in agriculture, while ten were found in forest habitat. A gradient of species-habitat was identified: Specialists/endemics tend to occur in natural areas, “intermediate species” in moderately modified areas and generalists in heavily modified areas. Generalists had higher abundances in anthropogenic areas, whereas specialists were found only in natural areas. Under insular conditions, land use changes can pose major threats for endemic and specialist raptors, seriously compromising their conservation. Endemic raptors do not cope well with habitat changes on the island, thus a rapid process of species impoverishment might be expected. Establishing a conservation program in Cuba is urgently needed.

Especies de hormigas del suelo en el Parque Nacional Natural Gorgona, Pacífico Colombiano

Gorgona is one of the two insular areas of the Colombian tropical rain forest at the Pacific and is amongst the most diverse biogeographic regions of the world, the Choco. This study compiles information on ant species from published (1991) and unpublished (2006) studies and provides new records for ant species collected in 2010. Ants were sampled and information was obtained from 15 sites in Gorgona island (13.82km2), including the Gorgonilla atoll (0.49km2). Collecting methods included pitfall traps, tuna baits, mini-Winkler extraction of leaf litter, Malaise traps, entomological net and direct search. The soil and understory ant inventory resulted in 107 ant species and morphospecies, 46 genera in 12 subfamilies. Myrmicinae held the highest species richness (37 species), followed by Ponerinae (27) and Formicinae (12). The richest genera were Pachycondyla (15 species), Camponotus (nine) and Pheidole (eight), while 30 genera were represented by a single species. Twelve species were very common (both in distribution and time): Azteca sp., Atta cephalotes, Camponotus sericeiventris, Eciton vagans, Ectatomma goninion, Gnamptogenys annulata, Odontomachus bauri, Pachycondyla bugabensis, P. harpax, P. verenae, Paraponera clavata and Wasmannia auropunctata. Direct search was the most efficient method to collect diferent species and was responsible for 52% of the total species found. Compared to other Neotropical islands, Gorgona holds a suprisingly high number of ant species, none of them invasive. The invasive Monomorium floricola, which was collected 20 years ago, was not found in 2010. These evidences suggest that ecological mechanisms and natural recovery processes in the ecosystem have generated microhabitats allowing their coexistence. Rev. Biol. Trop. 62 (Suppl. 1): 265-276. Epub 2014 February 01.

Feasibility of Invasive Grass Detection in a Desertscrub Community Using Hyperspectral Field Measurements and Landsat TM Imagery

Invasive species’ phenologies often contrast with those of native species, representing opportunities for detection of invasive species with multi-temporal remote sensing. Detection is especially critical for ecosystem-transforming species that facilitate changes in disturbance regimes. The African C4 grass, Pennisetum ciliare, is transforming ecosystems on three continents and a number of neotropical islands by introducing a grass-fire cycle. However, previous attempts at discriminating P. ciliare in North America using multi-spectral imagery have been unsuccessful. In this paper, we integrate field measurements of hyperspectral plant species signatures and canopy cover with multi-temporal spectral analysis to identify opportunities for detection using moderate-resolution multi-spectral imagery. By applying these results to Landsat TM imagery, we show that multi-spectral discrimination of P. ciliare in heterogeneous mixed desert scrub is feasible, but only at high abundance levels that may have limited value to land managers seeking to control invasion. Much higher discriminability is possible with hyperspectral shortwave infrared imagery because of differences in non-photosynthetic vegetation in uninvaded and invaded landscapes during dormant seasons but these spectra are unavailable in multispectral sensors. Therefore, we recommend hyperspectral imagery for distinguishing invasive grass-dominated landscapes from uninvaded desert scrub.

Risk factors for West Nile virus seropositivity of equids in Guadeloupe

In Guadeloupe, West Nile virus (WNV) activity was first observed in equids in 2002, and a high seroprevalence was found in 2003. The objective of our study was to determine individual and environmental factors associated with the risk of WNV seropositivity during 2002–2003. Fieldwork was conducted to retrospectively determine the location of equids at the time of virus circulation and to collect information regarding environmental and individual variables. Sera were collected from 369 equids out of an estimated total population of less than 500. Thirty-four environmental and individual variables were investigated. Equids had a higher risk ( p < 0.001) for WNV seropositivity if they lived within the proximity “distance less than 1.5 km” of marshes or swamp forests “a large freshwater formation behind mangroves” or if they remained outside after dusk. Equids living within the proximity of ouassous shrimp ( Macrobrachium rosenbergii) basins or sugar cane fields had a lower risk ( p < 0.001) for WNV seropositivity. These results confirm that WNV circulation is more likely in the humid coastal areas of Guadeloupe. The identification of risk factors is useful for predicting future emergence sites of WNV in the archipelago and other Neotropical islands, and to better target sentinel surveillance in the region.

Flora of Puná Island. Plant Resources on a Neotropical Island

Flora of Puná Island. Plant Resources on a Neotropical Island

Rainfall and Seasonal Changes in Arthropod Abundance on a Tropical Oceanic Island

Weekly sweeps for arthropods were taken and compared for an entire year (1977) on Grenada, West Indies, where there is a marked wet and dry season. The average wet-season abundance of arthropods was 2.3 times greater, and the wet-season biomass (grams) was 3.1 times greater, than that for the dry season. A significant correlation between biomass and abundance existed for the entire year. There was no change in arthropod size between wet and dry season. Intra-seasonal variations in arthropod abundance occurred, and were significantly correlated with seven-day accumulated rainfall following a three-week interval. Abundance of seven of 10 taxa showed the same three-week response to rainfall. Coleoptera were identified to species, so that species diversity, species overlap, and feeding guilds for the entire year could be compared to Central American Coleoptera. The results indicate the Coleoptera fauna on Grenada are more generalized compared to the tropical mainland, and composed of the same species whose abundance fluctuates seasonally throughout the year. MOST STUDIES OF SEASON ALITY in insect assemblages have been conducted on the tropical mainland (Bigger 1976; Buskirk and Buskirk 1976; Janzen 1973a, b 1976; Janzen and Pond 1975; Janzen et al. 1976; Janzen and Schoener 1968; Ricklefs 1975; Robinson and Robinson 1970; Smythe 1974; Wolda 1977, 1978). In contrast, there are only a few such studies of seasonality on tropical islands (Allan et al. 1973; Frith 1975; Janzen 1973a, b; Pipkin 1953). Data collected on a reguar basis throughout the wet and dry seasons have not been gathered for any oL the neotropical island insects. Such a study would be useful in detailing the basic difference between island and mainland ecology, as well as in adding new information to the subject of tropical seasonality. The purpose of this paper is to, investigate the seasonal changes that occur in tropical arthropods on an oceanic Caribbean island with a marked wet and dry season. Species diversity, overlap, and feeding guilds of the Coleoptera are compared to similar data from Central American studies.