Status and population trends of Eleonora’s Falcon Falco eleonorae in the Canary Islands

Eleonora’s Falcon Falco eleonorae Gené, 1839 is a colonial, diurnal raptor whose distribution ranges from the Mediterranean region to the eastern coast of Morocco and the Canary Islands, where it has the westernmost and southernmost breeding colonies (Cramp & Simmons 1998, Snow & Perrins 1998). The species is highly migratory, gathering in their breeding areas from mid-April to mid-October (Tucker & Heath 1994), its breeding period adapted to coincide with the postnuptial migration of small passerines (Cramp & Simmons 1998, Del Hoyo et al. 1994). After the application of proper census methods as outlined in the International Action Plan for this species (BirdLife International 1999), its global breeding population was recently estimated at more than 13,500 pairs (Dimalexis et al. 2008), although it could reach c. 30,000 mature individuals (BirdLife International 2008). The Spanish breeding population was estimated at 1,081 pairs distributed over the Balearic Islands (836 breeding pairs; Viada 2006), the Canary Islands (200; De León et al. 2008), and the Columbretes Islands (45; Viada 2006). The species is included in Annex I and II of the European Birds’ Directive 79/409/EEC and constitutes a priority species for conservation. The International Species Action Plan recommended a coordinated international survey as urgent action to conserve the species (BirdLife International 1999), which was accomplished in some countries within the framework of the project “Conservation measures for Falco eleonorae in Greece” LIFE 03NAT/GR/000091. In line with these recommendations, two main aims are pursued in this manuscript: (1) to update census data of the breeding population of Eleonora’s Falcon in the Canary Islands as a contribution to this global census project; (2) to evaluate the population tendency of Eleonora’s Falcon in the Canary Islands by using data from previous studies

Juniperus cedrus

The total area of occupancy (AOO) is calculated to be 29 km2. The AOO is based on presence within 1 km2 grid cells overlaid on 1:40,000 scale maps. Presence and absence records are derived from recent, extensive surveys carried out between 2004 and 2009 (Elliot 2009, Rumeu unpublished data 2010, Sequeira pers.comm 2010). The total population (n = ca 600) consists of five subpopulations/ locations found on five islands (Gran Canaria (n =12), Gomera (n = 100), La Palma (n = 250), Tenerife (n = 200) and Madeira (n = ca 40)). Each subpopulation/location is more than 60 km from the next and no single subpopulation contains more than 50% of the total population. These subpopulations are regarded as severely fragmented. The total population is estimated to be less than 600 mature trees and no subpopulation contains more than 250 mature individuals. Regeneration in some subpopulations is poor or absent, possibly due to reduced seed set (Rumeu et al. 2009), the decline of avian dispersers (Nogales 1999, Rumeu 2009) and the effects of grazing. In some locations fires have led to the loss of mature individuals. Together, these factors contribute to a continuing decline in the quality of habitat and number of mature individuals. On the basis of these data, Juniperus cedrus meets the criteria for Endangered

Los bosques de cedros en el Parque Nacional del Teide

El Parque Nacional del Teide alberga los principales núcleos poblacionales de cedro canario (Juniperus cedrus) en la isla de Tenerife. Los estudios científicos que aquí se recopilan han supuesto un importante avance en el conocimiento de esta especie y sientan la base para futuras investigaciones y actuaciones de gestión orientadas a la conservación y mejora de estas poblaciones. Distintas líneas de evidencia apuntan a una situación actual de fragilidad. Por un lado, la dispersión de semillas a larga distancia se ha visto mermada tras la desaparición de las parejas nidificantes de cuervo (Corvus corax) en el Parque, y actualmente depende en gran medida de la llegada invernal del mirlo capiblanco (Turdus torquatus), un ave que a su vez presenta problemas de conservación. Por otro lado, existe una marcada estructura genética local que evidencia la existencia de grupos de individuos emparentados con un nivel significativo de endogamia. Además, las condiciones ambientales a las que se ven sometidos los individuos relegados a zonas muy escarpadas tienen un efecto negativo en el potencial reproductivo. Pese a la protección que le confiere su presencia dentro de los límites del Parque, hoy en día el cedro sigue siendo una especie amenazada, especialmente por su incapacidad para resistir el fuego. Futuras investigaciones que permitan conocer la distribución original del cedro en la alta montaña y desvelar el potencial del mirlo capiblanco para conectar poblaciones distantes, permitirían llevar a cabo un reforzamiento más eficaz de las poblaciones que garantice su conservación a largo plazo

The key role of a Ring Ouzel Turdus torquatus wintering population in seed dispersal of the endangered endemic Juniperus cedrus in an insular environment

Although the Ring Ouzel has been considered accidental in the Canary Islands, it has been observed for the last five years in the high mountain zone of Tenerife (Canary Islands), showing it to be a regular winter visitor. Its inter- action with female Juniperus cedrus cones and seeds was studied by analysing its wintering diet during January–April 2008. This juniper is endemic to the Canaries and Madeira and is classified as endangered by the IUCN. Previously, its sole long-distance disperser was known to be the Raven Corvus corax, which is unfortunately now extinct in the distribution range of J. cedrus. The results show that the diet of T. torquatus in Tenerife consists mostly of female J. cedrus cones (95% of the biomass consumed). Due to the large amount of seeds dispersed by Ring Ouzels and the effectiveness in seed germination, this winter visitor constitutes an important vector in the dispersal of J. cedrus that appears to have gone undetected in the past. This passerine plays a key role in its seed dispersal system, being able to move seeds over long distances, thus connecting fragmented populations of this plant. The present work is one of the few cases described in which a plant endemic to an oceanic island is so dependent on a winter visitor, and highlights the importance of insular environments in the wintering range of the Ring Ouzel. Owing to the absence of native long-distance seed dispersers, the future fate of this conifer is now probably dependent on the wintering population of this thrush

Geographic variation and systematic of Juniperus phoenicea from Madeira and the Canary Islands: analyses of leaf volatile oils

All of the oils of J. phoenicea from the Canary Islands and Madeira were very similar. The volatile leaf oils were dominated by α-pinene (57.3 - 76%) as was the oil from Morocco (65.4%). This is higher than in J. p. var. phoenicea, Spain (41.2%) or var. turbinata, Spain, (25.8%). The Madeira and Canary Island oils had moderate amounts of β-phellandrene (0.5 - 8.0%), myrcene (2.3 - 3.3%), α-terpinyl acetate (trace - 5.0%), (E)-caryophyllene (0.4 - 1.4%), and trans-totarol (0.1 - 2.1%). There is some differentiation in the oils from Madeira and the Canary Islands from populations in Spain and Morocco, but not enough to justify the recognition of J. p. subsp. canariensis at this time

Reduced reproductive fitness of an endemic insular juniper population: an eco-genetic mediation hypothesis

The mutual reinforcement of multiple drivers of global change erodes ecosystem services and accelerates plant population decline worldwide. This is particularly the case for island ecosystems where anthropogenic activity has imperilled insular floras for centuries. Different hypotheses have put forward the combined effects of environmental shifts and genetic factors in driving fecundity decline in threatened populations. In this study, we combined population genetics tools and structural equation models to test the eco-genetic mediation hypothesis, that the environmental conditions influence genetic variation, which in turn affects plant fitness. Our study species is Juniperus cedrus, an endangered juniper species endemic to the Canary Islands. Juniper woodlands have been depleted since the arrival of human inhabitants confined extant populations to marginal lands. More recently, long-distance dispersers have been extirpated from the study area, potentially eliminating connectivity among fragmented populations. We expected strong intrapopulation subdivision and high levels of inbreeding and kinship that should negatively affect individual fitness. We found evidence of population subdivision into several mating neighbourhoods (K=13), some of them highly inbred. However, contrary to our expectations, neither inbreeding nor mean kinship mediated a population response to environmental factors. Our results suggest three remedial actions to reverse the declining demographic trends: (i) re-establish native vegetation to ameliorate local environmental conditions; (ii) restore dispersal services to increase connectivity; and (iii) monitor fitness decline to identify lagged effects associated with deforestation. Overall, this study shows that structural equation models combined with population genetics techniques are suitable tools to identify high-order effects among multiple drivers of global change that underlie forest decline

Development and characterization of 13 SSR markers for an endangered insular juniper (Juniperus cedrus Webb & Berth.)

We report the development of 13 microsatellite markers (SSR) for the Canarian endemic juniper, Juniperus cedrus. Evaluated in a set of 28 individuals sampled on the island of Tenerife, all markers showed polymorphism and displayed 56 alleles. The number of alleles ranged from 2 to 8, with an average of 4.31 alleles per locus. This set of SSR markers will be very useful in further studies on the population genetics or phylogeography of this endangered species, leading to more appropriate and successful management

Geographic variation and systematics of Juniperus phoenicea L. from Madeira and the Canary Islands: SNPS from nrDNA and petN-psbM

SNPs from nrDNA and petN-psbM (cpDNA) were analyzed of Juniperus phoenicea from Madeira, Canary Islands, Morocco, and El Penon, Spain along with J. p. var. turbinata from the Tarifa sand dunes,Spain. The analysis of the 18 SNPs revealed that the Macaronesian and Moroccan plants are identical or nearly so to J. p. var. turbinata and quite differentiated from J. phoenicea var. phoenicea. In contrast, the leaf terpenoids showed that the oils of the Macaronesian plants are more similar to the Moroccan plants and not as similar to J. phoenicea or J. p. var. turbinata. At present, it seems prudent to treat the Madeira and Canary Island plants as J. p. var. turbinata

Interspecific competition for frugivores: population-level seed dispersal in contrasting fruiting communities

Indirect interactions among plant species mediated by frugivorous animals can be central to population and community dynamics, since the successful seed dispersal of species may depend on facilitative or competitive interactions with heterospecific plants. Yet, empirical evidence on these interactions is very scarce and mostly available at small spatial scales, within populations. Because lipid-rich fruits are known to be preferred by migratory birds, here we test our prediction of competitive inferiority of a carbohydrate-rich fruited species (the hawthorn Crataegus monogyna) compared to lipid-rich co-fruiting species in a Mediterranean region where the bulk of seed dispersal relies on migratory birds. We assessed avian seed dispersal in both relative (fruit removal rate) and absolute terms (seed dispersal magnitude) in seven hawthorn populations distributed across an altitudinal gradient encompassing three contrasting fruiting contexts: hawthorn is scarce in the lowlands, common in the midlands, and the dominant fruit species in the highlands. We found evidence of seed dispersal reduction due to interspecific competition in the lowland populations, where lipid-rich fruits dominate. Besides, DNA-barcoding analysis of bird-dispersed seeds revealed that only a small subset of the local frugivore assemblages consumed hawthorn fruits in the lowland communities. Instead, the consumers of hawthorn fruits resembled the local frugivore assemblages where hawthorn fruits were more dominant and frugivore choices more limited. Our study suggests mechanisms by which the rarity or dominance of plant species might be jointly influenced by environmental constraints (here, precipitation along the altitudinal gradient) and frugivore-mediated indirect interactions among plants hindering or facilitating seed dispersal

Increasing efficiency and reducing bias in the sampling of seed-dispersal interactions based on mist-netted birds

Efficient and unbiased sampling of ecological interactions is essential to our understanding of the functions they mediate. Seed dispersal by frugivorous birds is a key mutualism for plant regeneration and community dynamics. Mist-netting is one of the most widely used methods to sample avian seed dispersal through the identification of seeds in droppings of captured birds kept inside cloth bags. However, birds may drop seeds on the ground before being extracted from the net, leading to a fraction of missing information due to ineffective sampling. Worryingly, this fraction could be unevenly distributed across bird and plant species, leading to sampling biases. Here, we assess the effectiveness of using a 1-m wide mesh below mist nets to sample seeds dropped by entangled birds. We used data from birds mist-netted during one-year-round. We sampled nearly 50% of interaction events and 75% of dispersed seeds on the mesh band below the mist nets (i.e. lost information without this optimization). The proportion of seeds sampled on the mesh bands was not evenly distributed among bird species but strongly related to bird size, ranging from 57–63% in warblers to 84–94% in thrushes. Moreover, the proportion of seeds sampled on the mesh was negatively related to seed size, although this relationship was weaker. We also evaluated accumulation curves of species and pairwise interactions with increasing sampling effort, both with and without using the mesh bands. The number of seed species sampled increased by 21% when using the mesh bands and the number of pairwise interactions by 36%. Our findings provide strong evidence on how inefficient and biased traditional mist-netting can be for sampling community-wide seed–dispersal interactions. We thus urge the use of mesh bands in future studies to increase sampling effectiveness and avoid biases, which will ultimately improve our understanding of the seed dispersal function