Northern Shrike Research Articles

The first record of the Siberian northern shrike (Lanius borealis sibiricus) in Lithuania with molecular confirmation

Climate change significantly affects biological diversity around the world. Trends of this phenomenon have also been noticed in Lithuania: in the past decades, 55 new bird species have been recorded. The recent record of a new species was done on 3 December 2019. During ordinary birds ringing carried out in Ventės Ragas Ornithological Station in Lithuania, an individual Siberian northern shrike (Lanius borealis sibiricus) was caught and ringed. Additional blood sample was collected for species confirmation. Based on identification keys and molecular mitochondrial cytochrome b analysis, we report that this is the first record of the Siberian northern shrike in Lithuania.

Tiger talk

Tiger talk

Relationship of Vertebrate Prey Size to Transport Mode and Distance in the Northern Shrike

This report presents experimental data on the transport of vertebrate prey by the Northern (Great Grey) Shrike (Lanius excubitor). The species is known to use three modes of transport: carrying prey exclusively with the bill, exclusively with the feet, and by transferring the prey from bill to feet while in flight. Shrikes often transport their prey a short distance from the point of capture (initial distance), followed by the longer flight to the impaling site (long distance). We found that the overall distance (initial plus long) and long distances, but not the initial distance, decreased with increasing prey weight. Greater weight of the prey coincided with reduced use of bill-only transport. The results reveal that Northern Shrikes are well adapted to carry their most common vertebrate prey, voles of the genus Microtus.

Northern Shrike (Lanius excubitor)

Northern Shrike (Lanius excubitor)

Northern Shrike (Lanius excubitor)

Northern Shrike (Lanius excubitor)

Temporal-Spatial Patterns of Food Caching in Two Sympatric Shrike Species

To study the temporal-spatial patterns of food caching in two sympatric shrike species (Northern Shrike Lanius excubitor and Red-backed Shrike L. collurio) in the north-western region of the Iberian Peninsula, I sampled cached prey. Northern Shrikes cached food mainly during the non-breeding period, and Red-backed Shrikes during the breeding period, depending on prey availability and energy requirement. Rate of food cached by Red-backed Shrikes increased as number of nestlings increased. Most prey cached by Northern Shrikes was used within 9 days. Red-backed Shrikes usually utilized their caches within 24 hr, mainly at dawn and dusk. Northern Shrikes used 62% of cached prey, and Red-backed Shrikes 88%. At least 6% of the prey cached by Red-backed Shrikes was kleptoparasitized, chiefly by wasps. Hawthorn (Crataegus sp.) and blackthorn (Prunus sp.) shrubs with cylindrical, thin and long thorns were preferred for caching, whereas rose (Rosa sp.) and bramble (Rubus sp.) shrubs with laterally flattened, wide and short thorns were avoided by both species. Red-backed Shrikes scattered their caches. The distance between the nest and the prey cached by the Red-backed Shrike depended on the availability of suitable thorny shrubs in the territory, with a tendency to cache close to the nest. Shrikes chose the upper and inner parts of the shrubs for caching, presumably to hide the food from kleptoparasites. I found an association between prey color and color of cache-shrub, suggesting that cryptic coloration influenced choice of cache site.

January Sighting of a Northern Shrike in Regina

January Sighting of a Northern Shrike in Regina

Prey Transport by Loggerhead Shrikes

Recent studies demonstrate that avian single-prey loaders preferably transport larger prey to their nests (e.g., Gronlund et al. 1970, Carlson 1985, Krebs and Avery 1985, Sonerud 1989). For central-foraging predators that carry prey for further handling and caching or for feeding of mates or young, the value of the prey is influenced by the energetic cost of transport (Orians and Pearson 1985). Shrikes (Laniinae) are birds of open-savannah habitats that exhibit central-place foraging and caching behavior. Northern Shrikes (Lanius excubitor) transport whole arthropods and reptiles to the nest, but decapitate mammalian prey (Gronlund et al. 1970). This species usually transports a higher-than-optimal load size, compared to other avian predators such as the Eurasian Kestrel (Falco tinnunculus) (Sonerud 1989). Sonerud (1989) reasoned that the optimal load-size carried by a Northern Shrike made up a higher percent of the body mass than it did for a Kestrel, because the relative cost of flying increases with increasing body mass. Sonerud also found that central-place foraging birds which differed in size and exploited the same prey type, differed in their selection of prey for transport over the same distance. Carlson (1985) found that Red-backed Shrikes (Lanius collurio) delivered to females prey collected close to the nest; he reasoned that the range of prey sizes economically worth returning decreased with distance and, inversely, the range of prey sizes available for self-feeding increased with distance.

Energetics and Growth Rate of Northern Shrike (Lanius Excubitor) Nestlings

Northern Shrikes (Lanius excubitor) breed in a variety of habitats, including deserts. Deserts are characterized by unpredictable food supplies, which can lead to a slow growth rate of nestlings. However, given that Northern Shrike males use prey from their caches to augment freshly caught prey in providing food for their mates and nestlings, we hypothesized that their nestlings do not have a slow growth rate, but one that is equivalent to that in other passerine nestlings from temperate areas. To test this hypothesis, we measured growth rates and energy use in Northern Shrike nestlings and fledglings. We also measured energy expenditure in two adult males that were attending nests. Growth rate of Northern Shrike nestlings was similar to that predicted for passerines in temperate areas and therefore our hypothesis was supported. However, metabolizable energy available in the cache amounted to only °7.2% of the total energy requirements of the nestlings or 4.2% of the total energy requirements of parents and nestlings during the nestling period. This suggested that other factors in addition to the cache were important in determining growth rate. These include (1) an extremely low maintenance energy require of the nestling; 30% of that predicted for a bird of its body mass when it weighed 10 g, which gradually increased to 70% at 50 g. This allowed for more of the energy intake to be used for growth and also reduced foraging costs of males; (2) the relatively low amount of body energy retained as a fraction of metabolizable energy intake, 0.15 to 0.16, indicating that more water per unit growth was incorporated than in other passerines. Energy expenditure of adult males was substantially lower than that predicted for a passerine of similar body mass. Males collected 4.83 time the energy that they consumed in order to provide their mates and offspring with food. Yet, their ratio of field metabolic rate to basal metabolic rate was only 2.33, the lowest reported value for adults feeding altricial young.

Erratum: Polygyny in the Northern Shrike (Lanius excubitor) in Israel

Erratum: Polygyny in the Northern Shrike (Lanius excubitor) in Israel

Nestling Transfer in the Northern Shrike (Lanius excubitor)

Nestling Transfer in the Northern Shrike (Lanius excubitor)

Polygyny in the Northern Shrike (Lanius excubitor) in Israel

Polygyny in the Northern Shrike (Lanius excubitor) in Israel

The Use of Hovering as a Search Method By the Northern Shrike

The Use of Hovering as a Search Method By the Northern Shrike

Northern Shrike Captures Shrew

Northern Shrike Captures Shrew

Some Additional Records of Birds in California

Some Additional Records of Birds in California

Cardinal versus Northern Shrike

Cardinal versus Northern Shrike

The Northern Shrike

The Northern Shrike

Feeding Behavior of a Northern Shrike

Feeding Behavior of a Northern Shrike

A Cycle in Northern Shrike Emigrations

A Cycle in Northern Shrike Emigrations

Northern Shrike and Enghsh Sparrow

Northern Shrike and Enghsh Sparrow