Based on limited research, the island loggerhead shrike,
Lanius ludovicianus anthonyi
has been considered a distinct subspecies endemic to the northern California Channel Islands. We used mtDNA ...control region sequences and microsatellite genotyping to compare loggerhead shrikes from the southern California mainland (
L. l. gambeli
), San Clemente Island (
L. l. mearnsi
), and the northern islands (
L. l. anthonyi
). Habitats on the islands are recovering due to the removal of non-native ungulates on the islands, but may be transitioning to habitats less supportive of loggerhead shrikes, so this evaluation comes at a critical time. We utilized 96 museum specimens that were collected over a century to evaluate both spatial and temporal genetic patterns. Analysis of multilocus microsatellite genotypes indicated that historical specimens of loggerhead shrikes (collected between 1897 and 1986) from the two northern islands of Santa Rosa and Santa Cruz are genetically distinct from adjacent mainland and island shrikes. Birds from Santa Catalina Island showed mixed ancestry and did not cluster with the northern island birds. Historical specimens of
L. l. mearnsi
from San Clemente Island also showed mixed ancestry. Our study provides evidence that a genetically distinct form of loggerhead shrikes,
L. l. anthonyi
, occurred on the islands of Santa Rosa and Santa Cruz.
Fascination with animals and their behaviour is one the most prominent patterns persisting in all human cultures. During the last decades, however, technological development and public access to the ...Internet have increased the speed and the extent of information sharing at an unprecedented rate, in some cases even challenging the traditional methods used in science. In order to understand the extent of this influence, we focused on the behaviour of shrikes. Shrikes are an enigmatic group of songbirds with a unique behaviour of impaling prey. We employed an extensive Internet search on YouTube (YT), a very popular and increasingly important source of information worldwide, for videos recording shrikes. Our analyses revealed that the number of shrike videos on YT is strongly positively correlated with classical knowledge on shrikes from books and scientific articles. Our results also suggest that in some cases YT may provide an alternative source of information on shrike ecology and behaviour. YT videos may thus provide new insights into the study of certain species or subjects and help identify gaps in ecological studies, especially in poorly studied species.
I investigated the relationship between the probability of nest predation and nest-site characteristics: (1) nest height above ground, (2) number of branches attached to a nest, and (3) number of ...thorny branches around the nest for a population of Bull-headed Shrikes (Lanius bucephalus) breeding in Japan. Thirty-eight nests were located during 2008 and 2009 of which 16 were lost to predation, 14 were successful in fledging young, four were abandoned, two were parasitized, and two may have been partially depredated, although the actual reason is unclear. Neither nest height nor the number of thorny branches was correlated with breeding success. However, the number of branches was negatively correlated with probability of nest predation. The primary predators were believed to be birds, based on physical evidence at depredated nests. A high density of branches around nests of Bull-headed Shrikes may ensure they are not easily discovered and depredated by predators.
Among 48 raptor species (birds of prey, owls, shrikes) recorded recently in Slovenia, some long-term monitoring activities are being conducted for more than half of them, mainly for conservation and ...research purposes. However, national coverage is achieved only in 15% of the species, whereas other monitoring programmes are more or less local. Two monitoring approaches are considered, the species specific approach and assemblage approach. Current ongoing monitoring programmes for raptors in Slovenia lack monitoring of breeding success, which is now confined to only a few owl species. Use of nestboxes should therefore be considered more broadly in the future for some species at least
Understanding the winter distributions of migrant birds is important because productivity and recruitment are influenced by conditions at several locations and periods in the life cycle of ...individuals. The western loggerhead shrike, Lanius ludovicianus excubitorides, is a threatened species in Canada, and its decline is attributed to potential limitations on the wintering grounds. We examined patterns of stable-hydrogen isotope (δD) distributions in feathers of loggerhead shrikes, primarily of L. l. excubitorides, during winter at three regions in north and central Mexico, to establish relative abundance and origins of migrants. We also investigated potential movements of Mexican winter resident individuals. Using shrike museum specimens of known summer provenance, a shrike deuterium base map for Mexico was developed from isotopic measurement of feathers of resident shrikes and use of a recently established feather base map for raptors in North America. Stable hydrogen isotope analyses of inner secondary feather (s9) of all loggerhead shrikes examined in Mexico during winter indicated that north-central (Region A), north-eastern (Region B) and south-central (Region C) sites in Mexico consisted of 28.1%, 73.7% and 63.8% of migrant individuals from northern breeding grounds, respectively. Isotopic evidence suggested movements of a few local residents birds (7.9%) into the Chihuahuan desert from south-western USA and north-eastern Mexico to winter.
We studied the breeding ecology of the Southern Grey Shrike (Lanius meridionalis) at the Shezaf Nature Reserve, Arava Valley, Israel, an extremely arid desert with mean annual rainfall of 30 mm. We ...color-banded 128 shrikes during 2007–2009. The breeding season lasted from late February until late June. We found 34 nests and a correlation between years with amount of precipitation and number of breeding pairs. Second broods after successful broods were found only in 2007 and were all unsuccessful. Most nests were in Acacia trees; pairs that nested in dry trees, lacking foliage, were more likely to fail. The average clutch size was 3.44; average number of nestlings was 1.95; and average number of nestlings that fledged was 1.24. These results are lower than other studies of the species, probably a result of the scarcity of food in the arid environment. Nest survival rate was higher during incubation than during rearing of nestlings (0.71vs. 0.62), and total nest survival was 44.5%. The arid Arava Valley influences breeding success of Southern Grey Shrikes, and the present severe drought could negatively influence persistence of the shrike population in the Arava Valley.
We studied the breeding ecology of the Grey-backed Shrike (Lanius tephronotus) in alpine shrub habitats in south Tibet. Shrikes nested between late May and early July at elevations of 4,010–4,540 m ...with a delay in nesting time with increased elevation. Nests were built mostly in bushes (83%), 0.7–2.1 m above ground. Clutch size averaged (± SD) 4.12 ± 0.67, range = 3–5 eggs and was smaller for pairs that nested later at higher elevations. Incubation by females began before clutch competition and lasted 15–18 days. Nestlings were cared for by both parents for 14–15 days. Breeding success, considered as the number of nest attempts that fledged at least one young, was 45.8%. Shrikes nesting in alpine habitats, compared with their lowland congeners, experienced shorter breeding seasons, produced fewer broods, smaller clutches, and larger eggs. They followed a life history strategy that allowed them to compensate for reduced annual fecundity under harsh conditions.
Extra-pair copulations (EPCs) are prominent features of avian mating systems. EPCs can be costly for both sexes, especially if extra-pair encounters are discovered by a social partner. The threat of ...extra-pair fertilization of the social partner could potentially result in physical punishment, reduced parental investment or divorce. In order to reduce the costs of EPCs, natural selection may favour behaviour that reduces the likelihood of detection of EPC by a social partner. Moreover, habitat structure may influence the efficiency of male paternity guards and, therefore, the possibilities of seeking and obtaining EPCs. We tested this hypothesis with the great grey shrike Lanius excubitor, a socially monogamous passerine bird, living in semi-open landscapes. We have found that 1) extra-pair and within-pair copulations (WPCs) occurred in different places, and 2) individuals of both sexes chose more secret places for extra-pair than for within-pair copulations.
PDF
