SPECIES

Northern Wheatear Oenanthe oenanthe Scientific name definitions

Erica H. Dunn, David J. T. Hussell, Josef Kren, and Amelia C. Zoerb
Version: 2.1 — Published October 25, 2022

Diet and Foraging

Introduction

Ground-foraging omnivore; primarily insectivorous. Main foods taken include adult and larval insects of a wide variety, spiders, other small invertebrates, and sometimes berries.

Feeding

Microhabitat for Foraging

Prefers to forage on bare ground or in areas of short vegetation where food accessibility and foraging efficiency is high (101). Most foraging is on the ground or < 0.5 m above ground (4). Activity is focused on areas where prey are more abundant, visible, or accessible: grass or tundra where vegetation is short or sparse, damp spots within arid regions (DJTH), and burned areas (4). Features that concentrate larvae and flies are favored, such as animal dung (2), tidal wrack (124), or decomposing vertebrates (155). Seasonal shifts in foraging locations correspond with changes in food availability (101, 83), and as grass becomes taller it is used less for foraging even if preferred foods are more abundant there (156).

Breeding birds forage over areas ranging widely in size, from 1 to > 8 ha; though usually within 100–150 m of the nest when gathering food for nestlings (157, DJTH; D. Arlt, personal communication).

At stopover sites, migrants select foraging areas that offer protective cover (158). Rate of fueling is reduced when predator numbers increase (159).

Food Capture and Consumption

The most common foraging tactic on open ground has been variously described as ‘hop and peck,’ ‘dash and jab,’ ‘pause and travel,’ and ‘running ground-gleaning.’ The bird moves forward by hopping, or with an asymmetric running movement intermediate between hopping and striding, then pauses to peck down at prey, flick aside surface material, or simply scan ahead before moving further (160). The forward dash, and occasional flicking of the wings, likely startle insects into movement that makes them more conspicuous (101), whereas displacement of surface soil reveals immobile prey such as larvae (161). Average distance traveled between pauses is typically about 30 cm (160) up to 80 cm (range 5–200, n = 43; 162). This distance is frequently accomplished with only 3–4 hops (4, 160); longer distances are traveled when larger prey items are detected. Birds foraging like this neither scan behind nor cover the same area twice (160). This foraging method accounted for 95% of prey captures recorded by Tye (160) and was also the primary method used by leucorhoa on Baffin Island (DJTH) and by libanotica in Iran (80).

The second most common foraging method is known variously as ‘perching and pouncing,’ ‘perch-to-ground sallying,’ or ‘sailing from perch to ground.’ Some authors report increased use of this method after heavy rains or where taller grass impedes ground foraging (4, JK), though at some sites it is used quite regularly (e.g., for 51% of prey captures in a study in Sweden; 163). Perched birds scan surrounding vegetation for 3–15 s before swooping down to catch prey or move to a new perch; perches are usually less than 1 m above ground (162; D. Arlt, personal communication). Individuals may hover over long grasses before dropping down, but hovering higher than 3 m is uncommon. Hunting from a perch is also common in Senegal, where there was a significant positive correlation between height of perch (80% ≤ 1 m) and distance to prey that were successfully captured (164).

A less common foraging method (4) is capture of slow-flying and low-flying insects by birds running or hopping rapidly towards the prey with head lowered and beak open, jumping 1–2 cm, if needed, for capture.

Aerial pursuits are usually short and close to the ground, although birds may fly up to 20 m when feeding on swarming insects (4). Adults in territories with taller ground cover often launch aerial pursuit from perches (D. Arlt, personal communication), including from roof-tops for birds nesting under roof tiles (T. Pärt, personal communication).

Several techniques are used to kill prey. Hard or large items are hammered or beaten on the ground. Legs and wings are often discarded from large heteropterans and grasshoppers (165, 166), though even large (2 cm) grasshoppers may simply be swallowed whole (165). Stingers may be removed from bumblebees (Bombus spp.) (167, 165). Removal of hairs from caterpillars is accomplished by running them through the bill from end to end prior to consumption (168). Flexible jaw muscles assist in handling prey (169).

During the breeding season, foraging techniques that involve standing and running on the ground indicate high foraging rates, whereas perching (and to some degree sallying) are associated with low rates (170).

Diet

Major Food Items

The diet consists primarily of insects taken from the ground, supplemented with other small invertebrates and some plant material. The range of animal food is broad (2), including adult and larval stages of beetles (Coleoptera), butterflies and moths (Lepidoptera) and flies (Diptera); also Hymenoptera (bees, ants, wasps, sawflies, ichneumons), grasshoppers and crickets (Orthoptera), bugs (Hemiptera), earwigs (Dermaptera), caddis flies (Trichoptera), scorpion flies (Mecoptera; 157), dragonflies (Odonata), lacewings (Neuroptera), springtail (Collembola), termites (Blattodea), spiders (Aranea), millipedes and centipedes (Myriapoda), woodlice (Isopoda), small snails (Gastropoda), earthworms (Oligochaeta), and in one case, a small lizard (2).

Berries are eaten primarily in late summer and fall, especially fruits of ground-hugging tundra plants such as crowberry (Empetrum nigram), bilberry (Vaccinium uliginosum), and common bearberry (Arctastaphylos uva-ursi; DJTH); also blackberry (Rubus fruticosus), rowan (Sorbus aucuparia), redcurrant (Ribes rubrum), elderberry (Sambucus nigra), juniper (Juniperus spp.; 114), plant seeds and saxifrage fruits (Saxifraga spp; 171). Birds migrating through Israel occasionally eat fruits of the shrub Rhamnus palaestinus (172).

Quantitative Analysis

Beetles often predominated in 8 studies of stomach contents, with Hymenoptera and Lepidoptera also abundant; see Cramp (2) for details. Proportions varied depending on region and season, presumably reflecting relative availability of prey items.

Data on food provided to nestlings in several European studies indicated essentially the same range of items as eaten by adults. Earthworms (Oligochaeta) are brought to nestlings but have not been documented for adults, possibly due to rapid deterioration of stomach contents. Food collected by neck-ringing of 24 young in Slovakia contained butterflies and moths (relative abundance 29%; 87% of which were larvae), beetles (22%), bees and wasps (14%), grasshoppers and crickets (12%), flies (11%), spiders (5), plant lice (Sternorrhyncha; 4%), cicadas, leafhoppers (Auchenorrhyncha; 2%), millipedes (1%), with <1 % each of segmented worms (including earthworms), snails, and scorpion flies (157). A large sample from the Netherlands (film records of 6,039 items brought to 11 nests) showed a similar range of food items, although there was considerable variation among individual nests (156): lepidopteran larvae (33% of items), scarabid beetles (17%), elaterid beetle larvae (14 %), dipteran imagos (7%), and spiders (5%). Among 4,024 items delivered to nestlings in Sweden, the most common included lepidoptera larvae (43%), adult dipterans (16%), adult beetles (7%), spiders (7%), and adult Hymenoptera (5%) (173). Unquantified film records of food brought to nestling leucorhoa on Baffin Island indicated similar types of food: spiders, larvae (tipulid, noctuid, lepidopteran, elaterid; adult lepidopterans, bees, beetles, and sometimes berries (DJTH).

Food Selection and Storage

Selection of prey is largely a result of which habitat is visited (see Feeding). Novel opportunities are exploited (174).

Young nestlings are fed relatively small and soft prey items (173). In contrast, items fed to older nestlings are often larger than those eaten by adults (175 ); perhaps a result of selective delivery rather than selective capture. Delivery of multiple items in one load is more frequent when several prey can be collected in one location (176); and delivery of prey in quick succession (often of a similar type) suggests that parents return to the site of previous success (175, DJTH).

Typical length of prey items delivered to nestlings in Sweden was 9–16 mm, but approximately 15–20% of items were longer (173); mean length in Slovakia was 15.3 mm; 157). Of prey items consumed by adults in southwestern Iran, 59% were < 5 mm, 33% between 5 and 10 mm, and 8% between 10 and 15 mm (n = 287 items; 177).

No evidence that food is stored.

Nutrition and Energetics

Information needed.

Metabolism and Temperature Regulation

Arctic and alpine birds often reach breeding grounds before snow is fully melted and temperatures are close to freezing; nesting birds occasionally endure late snowstorms (DJTH; C. M. Meier, personal communication). The same birds overwinter in hot parts of Africa, where the surface of unshaded sand can reach 40–80 °C (86). On overwintering grounds when temperature is > 30°C, birds seek shade of a stone or small bush (165). In northern Nigeria, birds spent up to 6 of 12 daylight hours sitting in shade (178).

Resting metabolic rate of oenanthe is constant between 25°C and 30°C ambient temperature: 1.69 kJ/h ± 0.41 SE (n = 36); it increases as temperature drops to 0, by a rate of 0.055 ± 0.585 kJ/°C (intercept = 3.11 ± 0.78 kJ; 96). Subspecies leucorhoa from Iceland have a higher nocturnal resting metabolic rate than do oenanthe from southern Norway (179). No data available for metabolic response to heat above the thermoneutral zone.

Energy expenditure of fully-grown nestlings at Öland, Sweden, was 52 kJ/d, while that of adults tending them was 87.4 kJ/d (no difference between the sexes, and lower than predicted based on body size; 180). In Scotland, average daily metabolic rate for breeding individuals was 95.3 kJ/d ± 17.0 SD (n = 24), with no difference between first-year and older birds, between sexes, or among parents tending natural broods of different sizes (181).

For thermoregulation of nestlings see Breeding: Young Birds.

Drinking, Pellet-Casting, and Defecation

Drinking

Information needed.

Pellet-Casting

Indigestible parts of prey are regurgitated as pellets (182, 165, JK). Some undigested foods are passed through the gut; to regurgitate, the head is held slightly down and forward and is lightly flicked until pellet is cast (4).

Defecation

For defecation see ( ) and Breeding: Parental Care.

Recommended Citation

Dunn, E. H., D. J. T. Hussell, J. Kren, and A. C. Zoerb (2022). Northern Wheatear (Oenanthe oenanthe), version 2.1. In Birds of the World (P. G. Rodewald and B. K. Keeney, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.norwhe.02.1