L. R. Monteiro’s research while affiliated with University of the Azores and other places

Aims To investigate chick growth, temporal patterns of chick food provisioning and the importance of indices of parental condition or quality, egg size and hatching date, to predict nestling body mass and wing‐length at fledging, and compare breeding and chick feeding characteristics between colonies in the northeast Atlantic.Methods A survey of Cory's Shearwater nests was carried out at Vila islet. A sample of 52 chicks, ringed and weighed at hatching, was selected to study chick growth and food provisioning.Results Hatching success (51%) was much lower than fledging success (87%). Both hatching date and egg size contributed to explain wing‐length at fledging, but hatching date, which was negatively correlated with wing‐length at fledging, had the most important contribution (22%). There was some indication that egg size may explain variation in fledging weight and the amount of food received by chicks. Food delivery and feeding frequency of chicks varied throughout the chick development stage and three phases were distinguished: (1) 0–29 days, the highest feeding frequency values and a linear increase in food delivery; (2) 30–69 days, an oscillation in food delivery and medium feeding frequencies; (3) 70–90+ days, a sharp decrease in both food delivery and feeding frequency.Conclusion Variation in food availability did not seem sufficient to override the overall importance of indices of parental quality in determining reproductive measures and chick provisioning. Breeding and feeding characteristics were similar between colonies in the northeast Atlantic, with variability in chick provisioning higher further south.

As on many other islands, most of the seabird species breeding in Portugal's Azores archipelago are now restricted to tiny remnants of their former nesting range, owing in large part to the introduction of mammals by humans. Praia Islet, 0.12 km2 in size, is home to five seabird species, four of which fall under the European listing of "conservation concern." Introduced rabbits (Oryctolagus cuniculus) on Praia had accelerated soil erosion through overgrazing, destroyed seabird nests, and competed for burrows with petrels. Restoration of seabird habitat on the islet began in 1995 and involved rabbit eradication, control of soil erosion, native plant reintroduction, and installation of artificial nests for common terns (Sterna hirundo), roseate terns (Sterna dougallii), and Madeiran storm-petrels (Oceanodroma castro). Rabbits were eradicated in 1997 using broadcast pellets containing poison. Since then, soil erosion has decreased, many of the reintroduced native plants have started to spread, and tern and Madeiran storm-petrel breeding numbers on the islet have increased by 1,548% and 43%, respectively. However, Praia Islet seabirds remain vulnerable owing to human recreational activities. This case study highlights the need to consider local conditions carefully when assessing restoration options to effect rapid mammal eradication. It also confirms the value of combining measures aimed at restoring native vegetation and improving seabird habitat quality with alien herbivore eradication.

We studied the diet of the Common Tern (Sterna hirundo) in several islands of the Azores during 1994, based on the analysis of 777 food pellets. The diet of Common Terns was based on a few species of small pelagic fish. Trumpet Fish (Macroramphosus spp.) dominated the diet in terms of both frequency of occurrence (84%) and numerical frequency (69%). This species, together with Boarfish (Capros aper), Blue Jack Mackerel (Trachurus picturatus) and lantern fish (Families Myctophidae, Sternoptychidae, Diretmidae), accounted for more than 96% of the prey taken by Common Terns on all the islands. Insects occurred in 10% of all pellets analyzed and were present in almost 15% of the pellets from Corvo. Lantern fish represented an important fraction of the diet of Common Terns in the Azores and included several species previously undescribed as prey of seabirds in the region. Comparisons with dietary data obtained in subsequent years showed little inter-annual variability in the frequency of abundance of the main prey species, except for the lantern fish, which exhibited a higher frequency of occurrence in 1995.

The importance of sympatric speciation (the evolution of reproductive isolation between codistributed populations) in generating biodiversity is highly controversial. Whereas potential examples of sympatric speciation exist for plants, insects, and fishes, most theoretical models suggest that it requires conditions that are probably not common in nature, and only two possible cases have been described for tetrapods. One mechanism by which it could occur is through allochronic isolation—separation of populations by breeding time. Oceanodroma castro (the Madeiran or band-rumped storm-petrel) is a small seabird that nests on tropical and subtropical islands throughout the Atlantic and Pacific Oceans. In at least five archipelagos, different individuals breed on the same islands in different seasons. We compared variation in five microsatellite loci and the mitochondrial control region among 562 O. castro from throughout the species' range. We found that sympatric seasonal populations differ genetically within all five archipelagos and have ceased to exchange genes in two. Population and gene trees all indicate that seasonal populations within four of the archipelagos are more closely related to each other than to populations from the same season from other archipelagos; divergence of the fifth sympatric pair is too ancient for reliable inference. Thus, seasonal populations appear to have arisen sympatrically at least four times. This is the first evidence for sympatric speciation by allochrony in a tetrapod, and adds to growing indications that population differentiation and speciation can occur without geographic barriers to gene flow. • Oceanodroma castro • phylogeography • genetic isolation • seasonal populations • storm-petrel

We relate fish biological and ecological characteristics to total and organic mercury concentrations to determine whether accumulation is influenced by trophic level, Hg concentration in the diet, and vertical distribution. Levels of total mercury and methylmercury were determined in the muscle tissue of eight species of fish: Pagellus acarne, Trachurus picturatus, Phycis phycis, P. blennoides, Polyprion americanus, Conger conger, Lepidopus caudatus and Mora moro, caught in the Azores. All such fishes are commercially valuable and were selected to include species from a wide range of vertical distributions from epipelagic (<200 m) to mesopelagic (>300 m) environments. Methylmercury was the major form accumulated in all species, comprising an average of 88.1% of total mercury. Concentrations of mercury (total and methylmercury) increased with age, length and weight. Based on data from other studies, mercury concentrations in fish diet were estimated. Mercury levels in food ranged from 0.08 to 0.32 ppm, dry weight. Hg concentrations in the food and in muscle tissue from different species were positively correlated. Total Hg levels in the muscles were approximately nine times those estimated in food. Total mercury concentrations in muscle were positively correlated with both trophic level and median depth. Such enhanced mercury bioaccumulation in relation to depth appears to be determined primarily by concentrations in food and ultimately by water chemistry, which controls mercury speciation and uptake at the base of the food chain.

Factors shaping population differentiation in low latitude seabirds are not well-understood. In this study, we examined global patterns of DNA sequence variation in the mitochondrial control region of the band-rumped storm-petrel (Oceanodroma castro), a highly pelagic seabird distributed across the sub-tropical and tropical Atlantic and Pacific Oceans. Despite previous classification as a single, monotypic species, fixed haplotype differences occurred between Atlantic and Pacific populations, and among all Pacific populations. In addition, Cape Verde and Galapagos birds formed distinct clades, estimated to have diverged from all other populations at least 150,000years ago. Azores hot season populations were also genetically distinct, lending support to previous phenotypic evidence that they be recognized as a separate species. Seasonal populations in Madeira probably represent separate genetic management units. The phylogeography of the band-rumped storm-petrel appears to have been shaped by both nonphysical barriers to gene flow and Pleistocene oceanographic conditions. Ancestral populations likely expanded through contiguous range expansion and infrequent long-distance colonization into their current breeding range. These findings suggest several possible revisions to the taxonomy of the band-rumped storm-petrel.

We examined the effect of prey type, repeated stomach flushing, digestion time, and meal size on the assessment of dietary intake of captive adult Cory’s shearwaters (Calonectris diomedea). For each of Cory’s shearwaters’ main prey type (fish, cephalopod, and crustacea), we used three different meal sizes and four digestion times, stomach-flushing the birds 1, 4, 8, or 16h after feeding. On average, fish and cephalopods showed similar percentages of mass recovery (between 23% and 33%), whereas crustaceans showed a recovery about 10–15% greater. Conversely, fish and crustaceans showed similar percentages of items recovered (between 52% and 77%), whereas cephalopods showed about 10–35% greater recovery rates. We found no significant differences in the percentage of individual prey items recovered and the interval between ingestion and recovery, over intervals ranging from 1 to 16h.

Mercury (Hg) was determined in adult Bonelli's eagles (Hieraaetus fasciatus) and their avian prey, from samples of feathers collected between 1992 and 2001 at the nesting sites of 21 pairs in Southwest Portugal. Eagle Hg levels showed great variation, reflecting primarily differences in diet composition and food chain biomagnification. Concentrations were positively correlated with the dietary proportion of insectivorous and omnivorous birds (e.g. egrets, corvids and thrushes), with very low levels for pairs feeding mainly on herbivores (e.g. rabbits, pigeons and partridges). Differences in prey contamination among breeding territories added to dietary effects in determining variation of Hg levels in eagles, shaping a spatial pattern that was largely consistent with a source of contamination in a coal-burning power-plant lying upwind of the study area. Despite this presumed contamination, Hg levels seemed to be of little concern to this eagle population, though there might be subtle deleterious effects on the reproductive output of a few pairs. This study emphasizes the need to account for dietary effects when biomonitoring Hg contamination using birds of prey.