Altitudinal Migration Research Articles

Feather traits in four southern populations of the Eurasian blackcapSylvia atricapilla: do altitudinal movements explain the differences?

Moult of birds is shaped by environmental and genetic drivers whose relative contribution to the structure of feathers may differ within and between populations. In this study, we compare some traits of tail feathers (growth bars, mass, rachis width and barb length) between four populations of the Eurasian blackcapSylvia atricapillabreeding at different elevations within the southwestern Palaearctic. We tested if these traits were related to the primary productivity of habitats (a surrogate of food availability) or were better explained as an adaptation to altitudinal movements. The distribution of primary productivity was positively related to blackcap abundance suggesting that the species tracked the most productive areas to breed. In this environmental setting, wing morphology (wing length, concavity and pointedness) suggested that lowland blackcaps were sedentary while blackcaps from highland areas were involved in altitudinal movements. The feathers of blackcaps inhabiting the highlands showed wider growth bars and rachis than those of the most productive lowland areas but did not differ in feather mass and barb length. Fast feather growth has been related to time constraints to moult and wider rachis to improve flight efficiency in migratory birds. Our results therefore suggest that differences in feather characteristics between southern populations of the Eurasian blackcap are better interpreted as an adaptive response to altitudinal migration than as a consequence of regional food availability.

Ecology of a Two-barred Crossbill (Loxia leucoptera) irruption to Norway in 2019–20: altitudinal migration and interspecific habitat differences

Cover photo: A male Two-barred Crossbill (Loxia leucoptera). Photo: Frode Falkenberg. 
 
 Two-barred Crossbills (Loxia leucoptera) have cyclic irruptions to Norway, but are generally uncommon and breeding is rare. Here I analyse data on a large irruption occurring in 2019–20 to assess the magnitude of the irruption and the ecological niche of the species. The irruption lasted one year, starting in July 2019 and ending in June 2020. Total numbers reported by birdwatchers to the website of the National Biodiversity Information Centre in Norway were ca. 7,000 individuals. Breeding indications were reported from nearly 100 sites. Analyses of elevation of records indicated that birds were often seen at low elevations before the breeding season in February–June, but moved to higher elevations during the breeding season. In a focal study area in SE Norway, breeding season surveys along elevational gradients indicated that Two-barred Crossbills occurred at higher elevations, and often close to summits of hills, perhaps representing preferences for more open forest habitats. Two-barred Crossbills often co-occurred with other seed-eating bird species, but presence was more closely related to numbers of Common Redpoll (Acanthis flammea), than to Eurasian Siskin (Spinus spinus) or cogeneric Common Crossbill (L. curvirostra). Similarly, the Common Redpoll also increased strongly in abundance with elevation, whereas the other two species did so to a lesser degree. These data suggest that the Two-barred Crossbill favors montane forests during the breeding season, and thereby has a different niche than the Common Crossbill which is distributed more widely across all elevations.

Hummingbird-plant interactions along an altitudinal gradient in northwestern Mexico

Comparing ecological networks along environmental gradients can enable a better understanding of the environmental filtering and coexistence mechanisms that determine community assembly. In the present study, we assessed hummingbird-plant network metrics at three sites along an altitudinal gradient in the Sierra Madre Occidental corresponding to tropical forest (148 and 289 m a.s.l.), ecotone (1131 and 1423 m a.s.l.) and pine-oak forest (1800 and 2218 m a.s.l.). We evaluated variation in the specialization (d’) of the hummingbird species and their visited plant species across altitude. We determined if hummingbird species inside the modules of the general network were separated by biogeographical origin, migratory behavior, or morphology. We assessed whether the role in the modular partition of hummingbird and plant species in the general network was related to traits of species. Finally, determined which traits were associated with the importance of different species within the network. We recorded 1050 interactions between 20 species of hummingbirds and 64 species of plants. We found that network metrics in the ecotone differed from other sites, reflecting the convergence between temperate and tropical forest flora and the midpoint in hummingbirds' altitudinal migration. As in previous studies, we found that hummingbird specialization was related to the bill length and found that the migratory status, particularly the altitudinal migratory species, was associated with the hummingbird specialization. The abundance of hummingbird species and flowers (ornithophilous and non-ornithophilous) along the gradient plays a central role in the importance within the network and in the formation of the modules.

Vegetation Type Preference and Habitat Use of Kashmir Markhor (<i>Capra falconeri cashmiriensis</i>) in Kazinag National Park, Kashmir, India

Habitat preferences of the least studied wild caprid, Kashmir Markhor ( Capra falconeri cashmiriensis ) was assessed in Kazinag National Park Kashmir by field surveys on 10 predetermined trails/transects and 6 vantage points during different seasons from 2017 to 2018. Data was collected directly from the field through direct observations and evidences of faecal pellets and footprints. Markhor was found to prefer elevations between 2200-3400m in different seasons. It prefers lower elevations in cold season and higher elevations in warmer seasons, thus shows altitudinal migration. Cliff habitat is most preferred habitat followed by conifers. Riverine and grassland habitats are least preferred whereas alpine meadows are avoided. During winter Markhor prefers south facing slopes (67.30%), while as all the slopes are used almost equally in other seasons. During fawning, females remain at lower elevations, steeper slopes and close to cliffs. The identification of the crucial and preferred areas of Markhor, by this study, can be utilized as a valuable guiding tool in devising conservation and management strategies for the revival of Markhor in Kashmir.

Patterns of partial migration of the Dead Sea Sparrow (Passer moabiticus) along the Great Rift Valley in Israel

Partial migration occurs when a population of animals contains both migratory and resident individuals. Following anthropogenic changes, the population of Dead Sea Sparrows (Passer moabiticus) in Israel, experienced a rapid expansion of its breeding range, from the Dead Sea northward along the Great Rift Valley. Appropriate climatic conditions, increased water availability and suitable trees to construct their nests enabled the Dead Sea Sparrows to breed in new areas. However, during non-breeding seasons, the climatic conditions and food availability is less suitable in some of these new areas.Dead Sea Sparrows colony, in an oasis in the Judean desert near the Dead Sea, was found to be mainly sedentary. However, recapture data, collected from numerous ringing projects along the Great Rift Valley, showed patterns of partial migration of northern populations. These include a unique altitudinal migration from above to below sea level. Female and juvenile Dead Sea Sparrows from northern populations migrate in autumn further south and in greater numbers than males and adults. This study sheds light on how the expansion of a passerine breeding range, due to anthropogenic activities, leads to the emergence of a variety of partial migration patterns.

Empirical modeling of the impact of climate change on altitudinal shift of major cereal crops in South Tigray, Northern Ethiopia

ABSTRACT Climate change is expected to alter the growing conditions of agricultural crops. With increasing surface temperature, future suitable areas for crop production will see an altitude shift. Such shift is an adaptation response of crops to climate change. However, in the study area there are a limited number of studies that have dealt with geographical shifts of crops caused by climate change. This study was conducted with the aim of assessing impacts of climate change on altitudinal migration of crops and length of growing period (LGP). The climate and crop modeling study were carried out using ArcGIS, Diva GIS and MaxEnt using 30 years of climate data for the period 1980 to 2009. Results showed that wheat (Triticum aestivum) and barley (Hordeum vulgare L.) would migrate upward along the altitudinal gradients in the coming 80 years. However, areas under these crops are expected to drop by 16–100%. Highly impacted areas are expected to increase, whereas low impacted and new suitable areas are expected to decline significantly. Suitable areas for sorghum (Sorghum bicolor) and teff (Eragrostis tef Zucc.) production are expected to increase. While wheat and barley are projected to be highly affected by future climate change, sorghum and teff should be relatively stable. No significant difference was observed in LGP between the considered RCP 2.6 and RCP 8.5 climate scenarios. Therefore, this study concluded that upward movement of crops was one mechanism to adapt to climate change, and new varieties resilient to future climate change needs to be developed.

Short term, but high risk of predation for endangered mountain caribou during seasonal migration

Migration occurs over a relatively short time period, but can result in an increased likelihood of mortality. Many populations of Southern Mountain Caribou, an Endangered subspecies in Canada, demonstrate altitudinal migration when moving between alpine and subalpine ranges. These caribou can encounter a high density of predators when transiting low- or mid-elevation valleys. We used camera traps to document the movements of caribou as well as moose, a sympatric ungulate that enhances the distribution and abundance of shared predators, through a mid-elevation valley that was characterized by resource roads and forestry clearcuts. The seasonal occurrence of moose coincided with the migratory movements of caribou (June–September). Similarly, the relative abundance of wolves and bears was greatest when caribou occupied the corridor. We used logistic regression to relate camera images to a range of ecological variables that we hypothesized influenced the seasonal distribution and risk of predation for moose and caribou. The most predictive model suggested that the probability of occurrence of caribou increased with temperature, precipitation, and week of the year. A factor for year revealed that the occurrence of caribou declined over the monitoring period. The most parsimonious model for moose included the same covariates as the most predictive model for caribou. A comparison of the frequency of caribou images with those crossings inferred from GPS-collar data revealed that the camera traps were relatively ineffective at monitoring the migratory movements of caribou. This study provided unique insights into the migration of a declining population of caribou, their interactions with predators, and the limitations of using camera traps to document the infrequent movements of low-density species.

Altitudinal migration of insects

AbstractA number of insects have been suggested to perform seasonal migration between low‐ and high‐altitude areas. In these insects, support for the occurrence of migration mainly came from observations that focal insects disappeared from a certain range of altitudes but appeared at different altitudes with short time lags. In some insects, further support was obtained by mark–recapture studies, analyses of the seasonal change of age structure or reproductive conditions in individuals from different altitudes and studies on dormancy or temperature tolerance. Other means that can be used to assess the occurrence of altitudinal migration are briefly mentioned. Two types of migration, the dormancy‐associated and dormancy‐independent types, are discriminated. In the former type, insects usually breed in spring, migrate to high‐altitude areas in late spring or early summer, usually for aestivation, and return to low‐altitude areas in autumn. In this type, the same individuals perform upward and downward migration. In the latter type, insects also perform upward migration in late spring or early summer and downward migration in autumn, but they breed both in low‐ and high‐altitude areas. The adaptive and evolutionary aspects of altitudinal migration are briefly mentioned.

A Review of Potential Impacts of Climate Change on Coffee Cultivation and Mycotoxigenic Fungi.

Coffee is one of the most traded commodities in the world. It plays a significant role in the global economy, employing over 125 million people. However, it is possible that this vital crop is threatened by changing climate conditions and fungal infections. This paper reviews how suitable areas for coffee cultivation and the toxigenic fungi species of Aspergillus, Penicillium, and Fusarium will be affected due to climate change. By combining climate models with species distribution models, a number of studies have investigated the future distribution of coffee cultivation. Studies predict that suitable coffee cultivation area could drop by ~50% under representation concentration pathway (RCP) 6.0 by 2050 for both Arabica and Robusta. These findings agree with other studies which also see an altitudinal migration of suitable cultivation areas to cooler regions, but limited scope for latitudinal migration owing to coffee’s inability to tolerate seasonal temperature changes. Increased temperatures will see an overall increase in mycotoxin production such as aflatoxins, particularly in mycotoxigenic fungi (e.g., Aspergillus flavus) more suited to higher temperatures. Arabica and Robusta’s limited ability to relocate means both species will be grown in less suitable climates, increasing plant stress and making coffee more susceptible to fungal infection and mycotoxins. Information regarding climate change parameters with respect to mycotoxin concentrations in real coffee samples is provided and how the changed climate affects mycotoxins in non-coffee systems is discussed. In a few areas where relocating farms is possible, mycotoxin contamination may decrease due to the “parasites lost” phenomenon. More research is needed to include the effect of mycotoxins on coffee under various climate change scenarios, as currently there is a significant knowledge gap, and only generalisations can be made. Future modelling of coffee cultivation, which includes the influence of atmospheric carbon dioxide fertilisation and forest management, is also required; however, all indications show that climate change will have an extremely negative effect on future coffee production worldwide in terms of both a loss of suitable cultivation areas and an increase in mycotoxin contamination.

New insights into the patterns and drivers of avian altitudinal migration from a growing crowdsourcing data source

Altitudinal migration is a common and important but understudied behavior in birds. Difficulty in characterizing avian altitudinal migration has prevented a comprehensive understanding of this behavior. To address this, we investigated the altitudinal migration patterns and explored potential drivers for a major proportion (~70%) of the entire resident bird community along an almost 4000 m elevational gradient on the main island of Taiwan. Based on the occurrence records collected by citizen scientists, we examined the seasonal shifts in the center and the upper and lower boundaries of elevational distributions for 104 individual species. We then built phylogeny‐controlled regression models to investigate the associations between the birds’ seasonal distribution shifts and seven of their traits, and examined whether the observed shifts can be explained by three main hypotheses on potential drivers. Results showed that at least 60 species (58%) seasonally changed their distributions along elevations. While most of them (42 species) tended to move downhill in winter, a considerable number of species (14) tended to move uphill. While the species breeding at high or low elevations tended to move downhill in winter, those breeding at medium‐low elevations tended to move or extend their distributions to higher elevations. Our regression models suggested that seasonal variations in climates and food availability could be major drivers of the behavior. However, the three hypotheses can only partially explain the observed downhill migration patterns and none of them can well explain the uphill patterns, indicating an important knowledge gap. This study investigated avian altitudinal migration from a new perspective with a novel and generalizable approach, and revealed interesting patterns that could be difficult to identify with conventional approaches. It demonstrated the power of citizen science data to provide new insights into this behavior by characterizing the general patterns and mechanisms across a large number of species.

Processes of Forest Cover Change since 1958 in the Coffee-Producing Areas of Southwest Ethiopia

We investigated the spatial relations of ecological and social processes to point at how state policies, population density, migration dynamics, topography, and socio-economic values of ‘forest coffee’ together shaped forest cover changes since 1958 in southwest Ethiopia. We used data from aerial photos, Landsat images, digital elevation models, participatory field mapping, interviews, and population censuses. We analyzed population, land cover, and topographic roughness (slope) data at the ‘sub-district’ level, based on a classification of the 30 lowest administrative units of one district into the coffee forest area (n = 17), and highland forest area (n = 13). For state forest sites (n = 6) of the district, we evaluated land cover and slope data. Forest cover declined by 25% between 1973 and 2010, but the changes varied spatially and temporally. Losses of forest cover were significantly higher in highland areas (74%) as compared to coffee areas (14%) and state forest sites (2%), and lower in areas with steeper slopes both in coffee and highland areas. Both in coffee and highland areas, forest cover also declined during 1958–1973. People moved to and converted forests in relatively low population density areas. Altitudinal migration from coffee areas to highland areas contributed to deforestation displacement due to forest maintenance for shade coffee production in coffee areas and forest conversions for annual crop production in highland areas. The most rapid loss of forest cover occurred during 1973–1985, followed by 2001–2010, which overlapped with the implementations of major land and forest policies that created conditions for more deforestation. Our findings highlight how crop ecology and migration have shaped spatial variations of forest cover change across different altitudinal zones whilst development, land, and forest policies and programs have driven the temporal variations of deforestation. Understanding the mechanisms of deforestation and forest maintenance simultaneously and their linkages is necessary for better biodiversity conservation and forest landscape management.

Producción, dispersión y banco de semillas en Lupinus montanus Kunth en el límite superior de su distribución altitudinal en el Nevado de Toluca

Introduction: In response to climate change, plants can adapt, migrate or die; however, migration by natural dispersion of seed can be very slow. Objective: To determine productive potential, dispersal distance and seed bank of Lupinus montanusKunth (lupine) at the upper limit (4 200 m) of its natural distribution at the “Nevado de Toluca” mountain. Materials and methods: The seed bank was estimated in an area of 1.88 m2. Three sampling sites were established with plants in reproductive stage (15 plants) isolated from other adult plants. Seed production was determined in traps placed at the four orientations of each plant and spatial pattern of dispersal was also determined. Results and discussion: Seedbank density was 4.26 seeds∙m-2 of soil. Lupinus montanus produced over 5 500 seeds per plant in one reproductive cycle; its seed potential was associated with plant height and number of stems. The number of seeds collected varied significantly (P < 0.0001) with respect to distance from the mother plant. The dispersion curve was adjusted (P < 0.01) to a negative exponential model (R2 = 0.849). Dispersal in the four orientations was symmetrical; 97 % of the seeds fell at a distance ≤2 m from the mother plant. Conclusions: Only 3.2 % of the seeds of L. montanus reached a distance greater than 2 m from the mother plant; however, dispersal is uniform in all orientations, therefore soil slope does not represent a limiting factor for the altitudinal migration of species.

Evolution of altitudinal migration in passerines is linked to diet.

Bird migration is typically associated with a latitudinal movement from north to south and vice versa. However, many bird species migrate seasonally with an upslope or downslope movement in a process termed altitudinal migration. Globally, 830 of the 6,579 Passeriformes species are considered altitudinal migrants and this pattern has emerged multiple times across 77 families of this order. Recent work has indicated an association between altitudinal migration and diet, but none have looked at diet as a potential evolutionary driver. Here, we investigated potential evolutionary drivers of altitudinal migration in passerines around the world by using phylogenetic comparative methods. We tested for evolutionary associations between altitudinal migration and foraging guild and primary habitat preference in passerines species worldwide. Our results indicate that foraging guild is evolutionarily associated with altitudinal migration, but this relationship varies across zoogeographical regions. In the Nearctic, herbivorous and omnivorous species are associated with altitudinal migration, while only omnivorous species are associated with altitudinal migration in the Palearctic. Habitat was not strongly linked to the evolution of altitudinal migration. While our results point to diet as a potentially important driver of altitudinal migration, the evolution of this behavior is complex and certainly driven by multiple factors. Altitudinal migration varies in its use (for breeding or molting), within a species, population, and even at the individual level. As such, the evolution of altitudinal migration is likely driven by an ensemble of factors, but this study provides a beginning framework for understanding the evolution of this complex behavior.

Testing four hypotheses to explain partial migration: balancing reproductive benefits with limits to fasting endurance

Seasonal migration is ubiquitous in animals, and yet its underlying cause(s) remain poorly known. Species exhibiting short-distance altitudinal migration and intraspecific variation in migratory behavior (partial or differential migration) are ideal study systems for examining the selective pressures that affect individual migratory decisions. We used an individually marked population of yellow-eyed juncos, breeding along a 1000-m elevational gradient and migrating up and down that gradient, to examine the morphological, behavioral, and reproductive traits associated with migratory behavior. We tested the four most well-known hypotheses proposed to explain partial migration: the thermal tolerance, fasting endurance, dominance, and arrival time hypotheses. Our results indicate that: (1) limits to juncos’ fasting endurance constrain their ability to overwinter at high elevations, in support of the fasting endurance hypothesis, (2) differences in body size mediate fasting ability and are associated with variation in migratory behavior and overwinter apparent survival, (3) migratory behavior interacts with reproductive success, in partial support of the arrival time hypothesis, and (4) additional mechanisms that are not captured by the four well-known hypotheses might better explain individual variation in migratory behavior. Less migratory females achieved greater nesting success the following breeding season. Among males, nesting success influenced migratory tendency the following winter. Successful males may either migrate to a more benign winter climate without paying reproductive costs, or high levels of parental effort might physiologically constrain their ability to overwinter in harsh climates. Migration is a costly behavior, so migration must yield fitness benefits, at least for some individuals. Species in which migratory behavior varies among individuals in the same population provide an under-utilized opportunity to understand the costs and benefits that mediate individual migratory decisions. By marking and tracking a population of yellow-eyed juncos, we found that larger individuals were less likely to migrate, and this held true even within a sex class (males). Smaller individuals were not only more likely to migrate but also had lower apparent survival, and these differences were driven by size-related differences in fasting ability. Less migratory females accrued reproductive benefits, but males with the highest reproductive success were not less likely to migrate as predicted by the arrival time hypothesis. Our study demonstrates that migratory decisions balance the potential reproductive benefits and survival risks of overwintering on high-elevation breeding grounds.

Variation in selective regimes drives intraspecific variation in life‐history traits and migratory behaviour along an elevational gradient

Comparative studies, across and within taxa, have made important contributions to our understanding of the evolutionary processes that promote phenotypic diversity. Trait variation along geographic gradients provides a convenient heuristic for understanding what drives and maintains diversity. Intraspecific trait variation along latitudinal gradients is well-known, but elevational variation in the same traits is rarely documented. Trait variation along continuous elevational gradients, however, provides compelling evidence that individuals within a breeding population may experience different selective pressures. Our objectives were to quantify variation in a suite of traits along a continuous elevational gradient, evaluate whether individuals in the population experience different selective pressures along that gradient and quantify variation in migratory tendency along that gradient. We examined variation in a suite of 14 life-history, morphological and behavioural traits, including migratory tendency, of yellow-eyed juncos along a continuous 1000-m elevational gradient in the Santa Catalina Mountains of Arizona. Many traits we examined varied along the elevational gradient. Nest survival and nestling growth rates increased, while breeding season length, renesting propensity and adult survival declined, with increasing elevation. We documented the migratory phenotype of juncos (partial altitudinal migrants) and show that individual migratory tendency is higher among females than males and increases with breeding elevation. Our data support the paradigm that variation in breeding season length is a major selective pressure driving life-history variation along elevational gradients and that individuals breeding at high elevation pursue strategies that favour offspring quality over offspring quantity. Furthermore, a negative association between adult survival and breeding elevation and a positive association between nest survival and breeding elevation help explain both the downslope and reciprocal upslope seasonal migratory movements that characterize altitudinal migration in many birds. Our results demonstrate how detailed studies of intraspecific variation in suites of traits along environmental gradients can lend new insights into the evolutionary processes that promote diversification and speciation, the causes of migratory behaviour, and how animal populations will likely respond to climate change.

Use of Citizen Science Data for Characterizing Patterns and Drivers of Avian Altitudinal Migration

Altitudinal migration, the seasonal and repeateing movement of animal individuals between breeding and non-breeding areas at different elevations, is a common and important but understudied behavior in birds. Difficulty in characterizing avian altitudinal migration has prevented a comprehensive understanding of both patterns and drivers of this behavior. To fill this knowledge gap, we investigated altitudinal migration patterns and underlying mechanisms for a major proportion (~70%) of an entire resident bird community on a subtropical island with an almost 4000-m elevational gradient. We quantified migration tendency of individual bird species based on the seasonal shift in the elevational distribution of their occurrence records in the eBird database. We then built phylogeny-controlled regression models to examine the associations between the birds’ migration tendencies and their functional traits to test major hypotheses on the mechanisms of altitudinal migration. The results showed a common but variable altitudinal migration behavior among the 118 species examined, with 40 and 11 species conducting post-breeding downhill and uphill migration, respectively. The species that have a narrower thermal tolerance range, can tolerate lower temperatures, have a smaller body size, have a more diverse or invertebrate-rich diet, or use an open nest had a higher downhill migration tendency. In contrast, no traits examined showed consistent associations with the uphill migration tendency. This suggests that post-breeding downhill and uphill migrations are driven by different processes and current hypotheses can only explain the former, but not the latter. This relatively comprehensive study demonstrated the power of citizen science data to provide new insights into an old research question from a novel perspective. Using the same approach, we are investigating the behavior in mountain regions around the world. With the global analysis, we will be able to understand the general patterns and mechanisms of avian altitudinal migration and also investigate their variation among mountain regions in different climate zones. In the face of rapid environmental changes in mountain ecosystems, the approach used in this study may also provide essential information for the conservation of mountainous biodiversity.

Early performance of two tropical dry forest species after assisted migration to pine–oak forests at different altitudes: strategic response to climate change

Assisted migration has been proposed as a strategy for adaptive management of forest species in response to expected effects of climate change, but it is controversial for several reasons. Tropical dry forests are among the most threatened ecosystems in the world. In Mexico, historically, land-use change and deforestation have been decreasing forest cover, and climate change is shifting the potential distribution of different forest types, exacerbating the risk of local extinctions. Assisted altitudinal migration could be a feasible strategy for reducing local extinctions in response to climate change and lack of landscape connectivity. Our objective was to evaluate survival and growth of Albizia plurijuga and Ceiba aesculifolia, two tropical deciduous forests species in Mexico. We transplanted 4-month-old seedlings to experimental raised beds at three altitudes (2100, 2400 and 2700 m a.s.l.), exceeding their upper regional limit of distribution (2000 m a.s.l.). We also tested seed germination at each altitude. We monitored the experiment for 10 months. For both species, as altitude increased and cold weather was more prevalent, plant performance declined. Within species, differences in individual growth were significant among altitudes. Overall survival was 18.5% for A. plurijuga and 24.5% for C. aesculifolia. Both species had higher survival and better growth at lower altitude, and no seedling emergence at any altitude. We conclude that assisted migration can be implemented for each species by an upward attitudinal shift within, and not exceeding, 400 m beyond their present upper altitudinal limit of distribution. Our results indicate that for many species that show altitudinal gradients at regional scales, unless current climate conditions change, the potential to establish outside their range is minimal.

Montane forest birds in winter: do they regularly move to lower altitudes? Observations from the Eastern Cape, South Africa

Seasonal altitudinal migration to lower altitudes including the coast has been ascribed to a number of forest birds, of which 14 species occur at Fort Fordyce Reserve in the Eastern Cape, South Africa. Based on our observations and ringing at this site (2007–2017), as well as concurrent data from the South African Bird Atlas Project (SABAP2), we suggest that in this region only three species, the African Dusky Flycatcher Muscicapa adusta, White-starred Robin Pogonocichla stellata and Barratt's Warbler Bradypterus barratti, are regular altitudinal migrants. For two other species, the Grey Cuckooshrike Coracina caesia and Yellow-throated Woodland Warbler Phylloscopus ruficapilla, local movements apparently occur, but these may take place within the coastal zone rather than between the coast and inland forests.

Hummingbird migration and flowering synchrony in the temperate forests of northwestern Mexico.

BackgroundMany species of birds are morphologically and physiologically adapted for migration. Migratory movements of birds can range from thousands of kilometers, such as when birds migrate from wintering to breeding sites in summer, to several kilometers, such as when birds migrate among habitats in a single mountain system. The main factor that influences bird migration is the seasonal fluctuation of food resources; climate, predation, competition for resources and endogenous programming are also important factors. Hummingbirds are highly dependent on nectar, so their migration is likely correlated with the blooming of plant species. The ecological implications of altitudinal migration in the mountains of North America as well as the latitudinal migration of Selasphorus rufus through Mexico are still poorly understood. To explore these issues, over three non-consecutive years, we evaluated interannual variation in the phenologies of a latitudinal migrant (S. rufus) and an altitudinal migrant (Amazilia beryllina) and their visited plants.MethodsWe assessed the relationship between two migratory hummingbirds and flower abundance in 20 fixed-radius plots (25 m radius). All available flowers were counted along transects (40 × 5 m) inside each fixed-radius plot. Sampling was performed every 10 days from November 12 through February 20 of 2010–2011, 2013–2014 and 2015–2016, resulting in a total of 11 samples of each plot per period. Phenological variation and the relationships among hummingbird abundance, flower abundance and vegetation type were evaluated using a generalized additive mixed model.ResultsS. rufus abundance was related to sampling time in the first and third periods; this relationship was not significant in the second period. A. beryllina abundance was related with the sampling time over all three periods. The abundance of S. rufus hummingbirds was significantly related to the number of Salvia iodantha flowers. The abundance of A. beryllina hummingbirds was related to the number of S. iodantha and Cestrum thyrsoideum flowers and the total number of flowers. We found a non-significant correlation between S. rufus and A. beryllina abundance and vegetation types.ConclusionContrary to expectations, the long-distance migration of S. rufus was not consistent over the sampling periods. The migration of S. rufus through the study region may be altered by changes in climate, as has occurred with other species of migratory birds. In the present study, the migration of S. rufus was correlated with the blooming of S. iodantha. In comparison, the altitudinal migrant A. beryllina responded to the availability of floral resources but was not associated with a particular plant. The migration of this latter species in the area probably depends on multiple factors, including climatic and demographic factors, but is particularly dependent on the supply of floral resources and competition for these resources.

Aves del departamento de Cundinamarca, Colombia: conocimiento, nuevos registros y vacíos de información

The department of Cundinamarca in Colombia is an area with diverse geographic and ecosystemic characteristics, a condition that makes it one of the regions in the country with highest diversity of birds. This study updates the list of birds in the department, as well as identifies changes in composition and gaps of information, through the recopilation of field data developed by the authors from 1990 to 2015, revision of different papers and databases, and consultation of experienced birdwatchers in the region. We found 941 records of bird species, of which 24 are endemic, 72 near endemic, 1 extinct, 39 nationally threatened, 101 migratory, and 45 present local and/or altitudinal migration. Of the total number of records, 701 correspond to the authors in 45 localities (48 are new records for the department). We note that there are gaps of information in departmental boundaries, especially in the region of the Magdalena River valley and Llanos Orientales. However, regions that have been more extensively sampled are not fully inventoried since new species for science are still being found.