Breeding times of birds: When do our native bird species breed?
The breeding seasons of birds determine when native species in Switzerland build nests, lay eggs and raise young birds. Anyone who tends gardens, cultivates fields or plans construction projects will benefit from a clear overview of the nesting season, typical breeding periods and legal guidelines. This guide summarizes the most important orientation values, shows species-specific differences - from blackbirds to swifts - and provides practical tips for protective measures in the municipality, canton and on your own property.
TL;DR - The most important facts in brief
- In the Swiss Plateau, the breeding season for birds roughly ranges from March to July/August, while at higher altitudes the nesting season often begins later (approx. 2-4 weeks).
- Several common species such as blackbirds, house sparrows and great tits manage 2-3 broods per season; long-distance migrants such as swifts and swallows usually have a shorter, compact breeding phase.
- Hedge cutting and tree felling are restricted in many places during the closed season. In many municipalities, cutting breaks apply between around March 1 and July 31 - check local rules.
- Nesting boxes, structurally rich hedges and later mowing times are particularly helpful for ground nesting birds such as skylarks and lapwings.
- Removing birds' nests is legally tricky: Wild birds and their nests are protected (JSG, TSchV). Obtain permission from the responsible authority.
What do bird breeding seasons mean - and what do they depend on?
The breeding season for birds refers to the period in which mating, nest building, clutch of eggs, breeding period and rearing of young birds take place. Temperature, length of day, food supply and weather extremes shift the start of breeding depending on the year, canton and altitude. In urban areas, resident species such as blackbirds and house sparrows often start earlier, while migratory birds such as barn swallows, house martins and swifts only start nesting after returning from their winter quarters. Agricultural dates and construction activities can also have an impact - which is why nest protection and adapted care practices are crucial.
Note: All monthly figures are approximate. Depending on the region (e.g. Central Plateau vs. Alps), microclimate and weather conditions, breeding windows may shift by several weeks.
Breeding seasons of birds in the course of the year in Switzerland
In Switzerland, the majority of breeding activity takes place in spring and early summer. The first territorial calls and courtship displays are often heard as early as February, with most clutches following between March and May. While species loyal to their habitat start early and sometimes lay several clutches, the breeding period for long-distance migrants is concentrated in a narrower time window from May/June. In high alpine locations, the entire process is delayed. For gardens, communities and agriculture, it is therefore advisable to plan in a way that takes into account the closed season and species diversity.
What role do nesting sites, clutches and breeding duration play?
The choice of nesting site - hedge, tree hollow, building crevice or ground - determines clutch size and duration until fledging. Cavity-nesting birds such as great tits and blue tits like to use nesting boxes, lay approx. 6-10 eggs, incubate for 12-14 days and feed young birds for a further 14-20 days (approximate values). Free-breeders such as blackbirds build cup-shaped nests in bushes; ground-nesting birds such as skylarks need open, extensively used areas. Swallows stick nests on facades or under eaves; swifts use crevices in buildings and breed compactly in midsummer.
Breeding times of birds by species: When do blackbirds, tits, sparrows, swallows and co. breed?
The following overview lists common species and their approximate breeding window in Switzerland, supplemented by typical clutches and the combined time of incubation and nesting phase. The information is intended as a guide; local observations and cantonal specialist offices provide the most precise information for projects.
Why are ground-nesting birds particularly worth protecting?
Ground-nesting birds such as skylarks and lapwings are particularly affected by early and frequent mowing, recreational pressure and predators. Nests are easy to overlook and young birds remain motionless in the grass for camouflage reasons. Mosaic mowing, protective strips, marking nests in consultation with farmers and a later first cut (depending on the vegetation and use, from around mid-June as a guide value) can help, provided this is feasible on the farm.
Hedge trimming, construction projects and nest protection: What is allowed during the nesting season?
During the closed season in Switzerland, wild birds and their nests are protected. Interventions on trees, facades and roofs that could destroy nests or disturb nesting birds are tricky. According to the Hunting Act (JSG) and the Animal Protection Ordinance (TSchV), many actions require a permit or are prohibited. Municipalities and cantons specify this in regulations or building requirements. For projects, ecological construction monitoring or an inspection by specialists is recommended - especially for building breeders such as swifts or house martins.
Practical tip: Carry out a nest check before each cut. If breeding birds or young birds are discovered, interrupt work and postpone it in consultation with the municipality or specialist agency.
What measures help during the breeding season in the garden, on buildings and in fields?
Structurally rich habitats and nesting boxes
Flower-rich hedges, wild shrubs and a mosaic of dense and patchy areas provide food and cover. Suitable nesting boxes (hole diameter, depth, orientation) support cavity-nesting birds. Artificial nests on protected facades are suitable for house martins and barn swallows - droppings boards help to keep buildings clean. Building breeders also benefit from the preservation and upgrading of existing niches.
Challenge: Renovations in early summer often clash with the nesting season. Solution: Postpone work to the winter months or arrange for building ecology support; plan replacement nesting sites well in advance.
Advantage: If you know the nesting times of birds, you can plan work in such a way that it is more efficient, legally compliant and biodiversity-friendly - a benefit for biodiversity and operations.
Top tips for practice (garden, community, agriculture)
- 1 If possible, schedule pruning work for late fall/winter; during the closed season only if it is clearly safe.
- 2 Size nesting boxes appropriately (e.g. approx. 32 mm flight hole for great tit/house sparrow) and place them at a height of approx. 2-3 m to protect them from the weather.
- 3 Use mosaic mowing and staggered cutting heights in the field; flexibly avoid areas with known nests.
- 4 Plan façade renovations with species protection at an early stage; maintain breeding niches or compensate with replacement roosts.
- 5 Feed only in a targeted and clean manner during the breeding season; native, pesticide-free plants are important as a permanent food source.
How do you recognize active nests - and when should you intervene?
Approaching movements with food in the beak, warning calls and droppings under nesting sites are reliable indicators of an active brood. Visual inspections should be carried out carefully and briefly as long as there is no disturbance. Barriers and resting areas help during construction work. If an injured young bird is found, professional advice is required. A winged nestling should usually be left in place; a still naked nestling should - if possible - be returned to the original nest. Otherwise, contact the responsible authorities (wildlife authority, local bird care station) - without linking, according to regional responsibility.
Legal framework: JSG, TSchV and municipal regulations in Switzerland
Under current Swiss law, wild birds, eggs, young birds and nests are protected. The Hunting Act (JSG) and the Animal Protection Ordinance (TSchV) form the basis, which is specified in many municipalities and cantons by regulations. Removing or moving birds' nests is generally not permitted during the breeding season and is only possible in clearly justified cases with a permit. A municipal closed season for hedge and tree trimming is also typical (often between around March 1 and July 31). Construction projects may be subject to conditions regarding a ban on construction and pruning, ecological construction monitoring and replacement nesting sites.
Good practice for businesses and municipalities
- Align scheduling with the breeding calendar; schedule critical work outside the main window.
- Before starting, carry out an inspection with an ornithological expert; mark and protect breeding sites.
- Communicate with residents and businesses to minimize disturbance.
Conclusion: Know the breeding seasons of birds - protect nature effectively
Taking into account the breeding seasons of birds creates legal certainty, avoids conflicts and promotes biodiversity. In the Swiss context, spring and early summer are considered the core seasons - which can vary depending on altitude and year. Practical levers include structurally rich habitats, adapted cutting and mowing dates, protection of existing breeding sites and species-appropriate nesting boxes.
- Recommendation 1: Hedge and tree maintenance should be carried out between October and February; during the nesting season only if it is clear that there are no nests.
- Recommendation 2: Integrate species protection into construction projects at an early stage (inventory, replacement nesting sites, construction period window).
- Recommendation 3: In agriculture, implement mosaic mowing, staggered cuts and breeding islands; provide targeted protection for ground nesting birds.
- Recommendation 4: Provide nesting boxes and artificial swallow nests; monitoring and cleaning outside the breeding season.
This is a good way of combining nature conservation, urban development and agricultural practice - for the benefit of bird species and humans alike.