April Atlasing Spotlight: Owls, Backyard Birds, and the First Warbler!

By Will Stollsteimer 1 Apr 2024

It’s April – the start of the peak breeding season in Pennsylvania! If you’ve been holding off on atlasing, now’s the time to get outside with your binoculars to get familiar with the areas you’ll be atlasing in and to check off early spring breeders. Remember to check out the Breeding Guidelines Chart to determine the optimal times to look for breeding behaviors for the birds of Pennsylvania.

Continuing Breeders


Many common, year-round resident species, including Downy, Hairy, Red-bellied, and Pileated Woodpeckers, entered their breeding season during March. Woodpeckers are cavity nesters, so keep a close eye on any cavities you see while out birding. These woodpeckers can also be heard drumming (equivalent to singing) or participating in courtship displays – auditory cues such as these can help clue you in to a nearby breeding pair. Targeting these species early in the season will ensure you have a great baseline to start from when the breeding season becomes busier in the late spring and summer.

Feeder Birds:

For all the bird feeder watchers out there, you may have noticed behavioral changes in some of your resident birds. The Carolina Chickadees are singing more, and maybe you’ve noticed your local Northern Cardinals chasing other cardinals from your yard. These behaviors represent the dawn of the breeding season for these species. Three well-known feeder birds moved into their breeding dates in March: Tufted Titmouse, Carolina Chickadee, and Northern Cardinal are all establishing territories and starting the breeding process. At this time of year, any observation of these species in suitable habitat warrants a breeding code. You may be able to find these breeders very close to home so this can be an excellent opportunity to boost your local atlas blocks.

New This Month


April is an excellent month to target owls via nocturnal surveys or diurnal scouting of habitats that could support these charismatic birds. The three species described here are also priority species for the PBA3. Should you be so lucky as to document breeding in these species, please provide additional information to help support your observation, including precise location, a description of the habitat, and photographs if possible.

By April 1st, most of Pennsylvania’s breeding owl species are already in safe dates, including the state-endangered Short-eared Owl. The Short-eared Owl is an open country specialist more frequently found in the state during the winter. Breeding populations remain sparse in the state, but they can be found breeding in reclaimed strip mines and other open areas, primarily in western and central Pennsylvania. Look for these birds preforming their “sky dancing” displays as a courtship ritual in open grassland habitats.

By the middle of April, Northern Saw-whet Owl and Barn Owl also move into full breeding weeks. Although many parts of Pennsylvania still host significant amounts of agricultural landscape, changing farming practices has led to a sharp decline in Barn Owls in the state. Barn Owls have been documented breeding in large tree cavities or man-made structures such as barn lofts, grain silos, and nest boxes. In suitable habitat, keep an eye out for males performing courtship displays, including display flights, where the male hovers in front of a perched female with legs dangling beneath his body, and nest showing displays, where the male gives an advertising call while repeatedly flying in and out of the nest site.

Our final owl species moves into safe dates in the last week of April. The Long-eared Owl is an enigmatic species that can be found breeding in dense vegetation surrounded by open or semi-open foraging habitat. The Long-eared Owl also has a very sparse frequency of observation within the breeding season in Pennsylvania. It takes a keen eye and a lot of patience to pick out one of these birds when it is hidden in a dense patch of vegetation. Courtship of the Long-eared Owl involves advertising songs and “zig-zag” flight display around the nest site. Be sure to keep a close eye on suitable habitats for Long-eared Owl come the end of the month.

(Note: These owl species have ‘Sensitive Species’ designation in eBird: year-round for Barn and Long-eared, and from April 20-June 30 for Short-eared Owl. This designation means that specific locations will be obscured and checklist details and comments will be omitted from public view in eBird.)

More Backyard Birds:

Like in March, a few more of our backyard residents come into their breeding season in April. On April 1st we can begin using all breeding codes for Carolina Wren, Mourning Dove, or European Starling. By the middle of the month, House Finches and Black-capped Chickadees are also in their breeding season. These familiar species can be easy to find and assign breeding codes to as they are ubiquitous (and sometimes loud!) in backyards and neighborhood parks. Finding strong breeding codes for these local species can remove pressure to focus on them when the breeding season begins to really heat up in the following months.

Our First Warbler:

As a sign of warmer and birdier times ahead, our first warbler species will begin settling into its breeding season by the middle of the month! The Louisiana Waterthrush is the earliest breeding warbler species here in Pennsylvania. The species tends to be found near fast-flowing streams in forested habitats; fortunately its piercing song can often be heard even over the sound of rushing water. Nests are typically nestled into cavities in stream banks, often in the exposed root systems of trees directly on the banks of streams. Both sexes assist in nest construction and during incubation, males can be seen bringing food to incubating females. Look for these behaviors to confirm breeding for this harbinger of spring.

Up Next

A Wealth of Neotropical Migrants, Sparrow, Ducks and More:

The dawn of May will bring with it our largest group of new breeders yet. Many of these birds are some of our early migrants from Central and South America. Sparrows and ducks are also well represented in the new species that will be within their breeding season. This will be a very busy month for the atlas and birding at any of your favorite local sites could yield some excellent finds and important additions to the atlas. The month of May will be a great time to focus on surveying species-rich habitats or going further afield and spreading the sampling effort beyond the usual habitats.