When you compare the birds of a manicured lawn with those that inhabit a grove of chokecherries, the difference is stark. The lawn might support a few starlings and robins. Perhaps, late in spring migration, a handful of desperate Swainson’s thrushes might stop by. The chokecherries, on the other hand, support an intricate community of life, from two-tailed swallowtail butterflies to dozens of species of songbirds. When the fruits ripen in late summer to a deep, juicy black, they attract cedar waxwings, Townsend’s solitaires, western tanagers, American robins, and house finches. Meanwhile, throughout the growing season, the foliage supports a diversity of insects – and the birds that eat them. Flitting among the leaves, you can find Wilson’s warblers, ruby-crowned kinglets, yellow-rumped warblers, and warbling vireos. 

When we consider the diversity of life around us, it’s easy to see a lot of bad news these days. We’ve lost 2.9 billion breeding birds in North America over the last 50 years. Scientists have reported steep declines of once-common insects. But by making a few simple decisions about what we plant in our gardens, we can be part of reversing these trends. In our yards, parks, and neighborhoods, we can provide homes for the birds, bees, and caterpillars. But doing this isn’t just about avoiding extinctions – it’s also a lot of fun.

This article is focused on plants for bird-friendly gardens in the western half of Montana, USA. If you live elsewhere, the specific plants will be different, but the general recommendations will be the same.

Getting started: habitat for birds

Every species of bird is unique in its life story. The habitats it uses, the foods it eats, where it nests, whether it migrates – all of this varies. Nevertheless, all birds need food, shelter, water, and safety from predators. Plants provide excellent food and shelter – especially particular species of plants that are native to the local landscape. But before we get into the specifics of these plants, let’s consider water and predators. 

Some birds, such as American kestrels, can get most or all of the moisture they need from their food. Otherwise, birds need to drink water. Including a source of water in your garden, such as a regularly cleaned bird bath or a backyard wetland, can attract birds to drink or bathe.

Watch out for predators

What about predators in our yards? Outdoor cats are incredibly deadly for neighborhood songbirds. In the United States alone, cats kill well over a billion birds a year. This number is so large that it’s almost unimaginable. But there are a lot of outdoor cats in the United States: around 50 million pets, in addition to as many as 100 million feral cats. Managing outdoor cats, especially feral ones, can be a contentious topic. But keeping your own cats indoors is a relatively easy step to take. By doing so, you’ll help ensure that your bird-friendly garden doesn’t become a death trap for songbirds.

Windows may not be predators, but they’re another deadly neighborhood hazard for songbirds. In the United States, they’re estimated to kill over 350 million birds a year. An article by the Cornell Lab of Ornithology gives an overview of this issue and discusses several solutions. Of these, Acopian Bird Savers are probably one of the most elegant. This is an unobtrusive, low-tech design that consists of vertical rows of cords, spaced four inches apart, that hang from the outside of the window. You can make your own out of parachute cord or bamboo, or you can order them online.

Including different habitat features

Broadly speaking, all birds are associated with one or more of three general habitats: forest, prairie, or wetland. What habitats make up the larger landscape surrounding you? The answer to this question will shape the possibilities for your bird-friendly garden.

Is your home in the middle of a Douglas-fir forest, or is it in a valley-bottom subdivision? Clark’s nutcrackers probably won’t visit your garden unless you have patches of conifers close to you. Similarly, you probably won’t attract marsh wrens or Wilson’s snipes to your yard unless you live very close to a wetland. Meanwhile, many prairie birds need relatively large patches of grasses and herbs. So unless this describes the area around your house, you probably won’t have grasshopper sparrows or western meadowlarks in your yard. Many birds of thickets and forest edges, on the other hand, will readily use yards during migration or the breeding season. And, of course, there are a variety of birds that use more than one of these habitats.

In general, in order to make your yard more inviting for birds, it’s worth considering components of all three habitats: forest, prairie, and wetland. A small water feature probably won’t attract Wilson’s snipes – but, once again, a bit of water in the yard will allow birds to drink and bathe. A prairie patch the size of a front yard is unlikely to bring in grasshopper sparrows, but it will offer important seeds and insects for thicket-edge birds such as chipping sparrows. And patches of native shrubs or trees, such as chokecherries, provide food and cover for a wide diversity of migrating and nesting songbirds.

Why native plants?

You’ve probably noticed that I keep mentioning native plants for birds. Why does this matter? you might be wondering. Perhaps you’ve noticed that robins and Bohemian waxwings often eat the fruits of Russian-olive (Elaeagnus angustifolia), a frequently-planted invasive that escapes from cultivation to compete with the cottonwoods and willows along our waterways. Or you might have noticed a house finch or pileated woodpecker pecking at an apple, another non-native fruit. 

Yes, there are non-native plants that certain birds will use. But, all things considered, native plants are far superior for our birds. Why? It comes down to food – and, specifically, insects. Doug Tallamy, a researcher who has spent decades studying birds and insects, writes that 96% of North American land birds rely heavily on insects during the breeding season. Soft, juicy caterpillars are especially important. And whereas native plants have coevolved with native insects, non-native plants are comparative deserts for insect diversity.

A non-native plant like Russian-olive may still provide fruits that feed a few species. But in comparison with a chokecherry or another native plant, it’s much less useful for most of our birds. If you want to attract an abundance of birds to your yard, then native plants are the way to go.

Okay, which plants should I plant for the birds? you’re probably asking. Here are some recommendations for western Montana, organized by the foods they provide.

Native plants for insects

What sorts of native plants provide our birds with the most insects? In order to give region-specific recommendations, Doug Tallamy and Kimberley Shropshire teamed up with the National Wildlife Federation to create an interactive website, searchable by zip code. For each zip code, this tool predicts the number of caterpillar species that different native plants will support. And in North America, it turns out, wherever you are, just a handful of native plants support most of the caterpillars.

Around Helena, Montana, willows are at the top of the list. These shrubs host up to 309 species of caterpillars – juicy protein packets to feed our nesting birds. Many of our native willows grow in wetlands, but Scouler’s willow (Salix scouleriana) and sandbar willow (Salix exigua) are common species that often grow in somewhat drier areas.

Cottonwoods and aspens are also high on the list, hosting up to 245 butterflies and moths. Among the cottonwoods are black cottonwood (Populus balsamifera) and plains cottonwood (Populus deltoides) – but keep in mind that these trees are notorious for dropping branches. Meanwhile, quaking aspen (Populus tremuloides) forms thickets from underground rhizomes. For these reasons, cottonwoods and aspens are best-suited for larger yards. 

Chokecherry (Prunus virginiana) and American plum (Prunus americana) are thicket-forming shrubs that are excellent for bird habitat. (They support up to 227 species of caterpillars – and check out this article for an exploration of other miniature insects that live on chokecherries.) However, if you live in an area with a high risk of bear conflicts, keep in mind that chokecherries and plums can attract bears when the fruits get ripe in the fall.

Birches, alders, and pines

Our native birches host 211 species of caterpillars. Water birch (Betula occidentalis) is a small tree that often grows along streams; paper birch (Betula papyrifera) gets much larger. And birches do more than just provide lots of insects. Their trunks (like those of cottonwoods and aspens) also make popular homes for cavity-nesting birds like black-capped chickadees and house wrens. (If you don’t want to wait for your trees to grow, the Cornell Lab of Ornithology also provides thorough instructions for nest box construction.) The related thinleaf alder (Alnus incana) is a large shrub or small tree that hosts 196 species of butterflies and moths.

Among the conifers, pines (Pinus spp.) are important for caterpillars, supporting up to 188 species. Around Helena, ponderosa pine (Pinus ponderosa) and limber pine (Pinus flexilis) are good options. However, keep in mind that they grow to be rather large trees. Also, depending on your surroundings, you might not want to plant them near your house due to fire risk.

Goldenrods, strawberries, and more

What about herbaceous plants? For caterpillars, goldenrod is at the top of the list, hosting 65 species. Common goldenrods in Montana include giant goldenrod (Solidago gigantea), Canada goldenrod (Solidago canadensis), and Missouri goldenrod (Solidago missouriensis). These plants are commonly blamed for late-summer allergies, but this is a myth: the culprits are typically ragweeds (Ambrosia spp.), which bloom around the same time.

Other herbs that support substantial numbers of butterflies and moths are native strawberries and sunflowers. Wild strawberries (Fragaria virginiana and Fragaria vesca) are low-growing; they may not compete well with taller, more vigorous plants. Sunflowers, on the other hand, are both tall and vigorous. In Montana, common sunflower (Helianthus annuus) is an abundant annual that often grows along roadsides. We also have two common perennial species, Nuttall’s sunflower (Helianthus nuttallii) and Maximilian sunflower (Helianthus maximiliani). 

Lupines and sagebrushes are also worthy of mention, supporting up to 40 and 35 species of caterpillars, respectively. Silvery lupine (Lupinus argenteus) and silky lupine (Lupinus sericeus) are a couple of Montana’s common lupines. Sagebrushes are very diverse in Montana and include shrubs such as big sagebrush (Artemisia tridentata) and silver sagebrush (Artemisia cana) as well as herbs such as fringed sage (Artemisia frigida) and white sagebrush (Artemisia ludoviciana). 

Native plants for fruits

I’ve already mentioned chokecherry for the diversity of insects that it hosts. In addition to the insects, this shrub is also a phenomenal fall fruit resource for cedar waxwings, American robins, and many other birds. And besides chokecherry, there’s a wide selection of other native fruits that attract birds, from July onwards through the winter. Many of these plants also host a notable diversity of caterpillars (though they support fewer species of caterpillars than the shrubs and trees I’ve already mentioned).

Red-osier dogwood (Cornus sericea) offers clusters of small white fruits from mid-summer through fall. Gray catbirds and white-crowned sparrows are among the birds that feed on them. This medium-sized shrub also has brilliant red fall foliage.

The native currants – such as golden currant (Ribes aureum) and bristly gooseberry (Ribes setosum) – are some of the earliest fruits to ripen in the summer. They provide a tasty snack for birds and people alike. Serviceberry (Amelanchier alnifolia) is another popular summer fruit for cedar waxwings, western tanagers, and thrushes. 

Elderberry, snowberry, and more

Blue elderberry (Sambucus cerulea) ripens in the fall, as does western mountain-ash (Sorbus scopulina). The snowberries – common snowberry (Symphoricarpos albus) and western snowberry (Symphoricarpos occidentalis) – also ripen in the fall, but their fruits stick around through the winter. So do the wild roses, such as Woods’ rose (Rosa woodsii) and Nootka rose (Rosa nutkana). Silver buffaloberry (Shepherdia argentea) is a great fall fruit that sometimes remains through mid-winter. Note that this is a large, thorny bush, though, and separate male and female plants are needed for pollination.

Rocky Mountain juniper (Juniperus scopulorum) is a tall shrub that provides winter “berries” (actually fleshy cones) for Bohemian waxwings, Townsend’s solitaires, and American robins. Keep in mind that juniper, like silver buffaloberry, has separate male and female plants, so you’ll need both in your general area for pollination to occur. Juniper is also highly flammable – so it’s probably not a good idea to plant it in areas with high fire risk. Montana also has two lower-growing juniper species that provide options for smaller spaces: horizontal juniper (Juniperus horizontalis) and common juniper (Juniperus communis).

Native plants for seeds

Many birds – such as American goldfinches, American tree sparrows, and pine siskins – commonly feed on seeds. In the case of sparrows, it’s often hard to see exactly what they’re eating, since they feed on the ground. Nevertheless, a few seed-bearing plants are especially noteworthy for the birds they attract. Montana’s native sunflowers – the annual common sunflower and the perennial Nuttall’s and Maximilian sunflowers – reliably attract goldfinches and pine siskins when their seeds ripen in the fall. Our pines, such as ponderosa and limber pine, feed nomadic groups of conifer-seed specialists such as red crossbills and Clark’s nutcrackers. Thinleaf alder, water birch, and paper birch provide winter seeds that often attract common redpolls and pine siskins. And many other native plants, from asters to grasses, also produce seeds that various finches and sparrows may use.

Native plants for nectar

What about hummingbirds? These tiny, beloved hoverers often catch tiny insects – so providing habitat for insects is important to them, too. In addition, they’re well-known for their nectar-feeding habits. A variety of native plants with long, tubular flowers are popular hummingbird plants. These include orange honeysuckle (Lonicera ciliosa), yellow columbine (Aquilegia flavescens), scarlet gilia (Ipomopsis aggregata), beebalm (Monarda fistulosa), and the penstemons. Among western Montana’s common penstemons are Alberta beardtongue (Penstemon albertinus), fuzzy-tongue penstemon (Penstemon eriantherus), and small-flower beardtongue (Penstemon procerus). In addition, some of the plants I’ve already mentioned for insects or fruits – such as golden currant – are popular nectar sources for hummingbirds.

Obtaining plants

Where can you find these plants? Some local nurseries, such as GardenWerks in Helena, carry a limited selection of native plants. In addition, I was able to find three retail nurseries in western and central Montana that offer a wide selection of natives: 

• Blake Nursery, Big Timber, MT: https://www.blakenursery.com/
• Center for Native Plants, Whitefish, MT: https://centerfornativeplants.com/
• Pipilo Native Plants, Charlo, MT: https://www.pipilonatives.com/

(A fourth nursery, Southwest Montana Native Landscapes, has unfortunately closed, though it still shows up on a Google search.)

To find out more, I contacted these nurseries and asked them which plants they stock, of those I list in this article. Find their responses here.

In addition to these retail nurseries, there are a few other commercial sources of native plants in western Montana. For larger projects, the Montana Conservation Seedling Nursery and Great Bear Native Plants accept wholesale orders. And if you want to start your own plants, Native Ideals sells locally grown seeds for a variety of Montana species.

Note that certain nurseries that don’t specialize in native plants may “stretch” the concept of “native” to include species that aren’t from Montana. For example, Penstemon strictus is sometimes sold as a native plant, but it grows in the wild in the southern Rocky Mountains and doesn’t reach Montana. When in doubt, look a plant up on the Montana Natural Heritage Program’s Montana Field Guide to learn about its status in the state, or check out the Biota of North America Program’s county-level range maps. These maps are organized by genus and show the distribution, by county, of all wild and naturalized plants in the United States.

The bird-friendly garden

Is this a comprehensive list of all of the plants that are important for bird-friendly gardening in Montana? No! I’ve neglected to mention native maples (Acer spp.), raspberries (Rubus spp.), hawthorns (Crataegus spp.), and many others.

When it comes to growing habitat for birds, there are always more plants you can add. But even if you do nothing more than add a patch of chokecherries and a handful of goldenrods to your yard, where previously there was just lawn, you’ll have made a good start. As the chokecherries leaf out in the spring, wait for the yellow-rumped warblers to appear, hunting insects. When the fruits ripen in the fall, look for the flocks of cedar waxwings and robins. And if you have the space in your yard to include all of the plants I’ve mentioned here, along with a water source… in a few years, your yard will be a paradise for birds.

This story was produced with support from the Gold Country Master Gardener Association.

Further reading

Acopian Bird Savers: prevent birds from flying into windows. Retrieved from https://www.birdsavers.com/

American Bird Conservancy. (2013, January 29). Outdoor cats: single greatest source of human-caused mortality for birds and mammals, says new study. Retrieved from https://abcbirds.org/news/outdoor-cats-single-greatest-source-of-human-caused-mortality-for-birds-and-mammals-says-new-study/

Biota of North America Program. (2014). BONAP’s North American Plant Atlas (NAPA). Retrieved from http://bonap.net/NAPA/Genus/Traditional/County

Center for Native Plants. (n.d.) Our most bird friendly species. Retrieved from https://centerfornativeplants.com/wp-content/uploads/2022/04/cnp_plantselection_birds-1.pdf

Cornell Lab of Ornithology. (2016, December 5). FAQ: Outdoor cats and their effects on birds. Retrieved from https://www.allaboutbirds.org/news/faq-outdoor-cats-and-their-effects-on-birds/

Cornell Lab of Ornithology. (2023). All about birdhouses. Retrieved from https://nestwatch.org/learn/all-about-birdhouses/

Cornell Lab of Ornithology. (2023, February 24). Why birds hit windows – and how you can help prevent it. Retrieved from https://www.allaboutbirds.org/news/why-birds-hit-windows-and-how-you-can-help-prevent-it/

Friends of the Mississippi River. (2022). Goldenrod or ragweed: which causes allergies and which benefits pollinators? Retrieved from https://fmr.org/updates/conservation/goldenrod-or-ragweed-which-causes-allergies-and-which-benefits-pollinators

Loss, S.R., Will, T., Loss, S.S., & Marra, P.P. (2014). Bird-building collisions in the United States: estimates of annual mortality and species vulnerability. The Condor 116(1):8-23. Retrieved from https://bioone.org/journals/the-condor/volume-116/issue-1/CONDOR-13-090.1/Birdbuilding-collisions-in-the-United-States–Estimates-of-annual/10.1650/CONDOR-13-090.1.full

Montana Natural Heritage Program. (n.d.). Montana Field Guide. Montana State Library. Retrieved from https://fieldguide.mt.gov/default.aspx

Narango, D.L., Tallamy, D.W., & Shropshire, K.J. (2020). Few keystone plant genera support the majority of Lepidoptera species. Nature Communications 11:5751. Retrieved from https://www.researchgate.net/publication/345818119_Few_keystone_plant_genera_support_the_majority_of_Lepidoptera_species

National Wildlife Federation. (2023). Native plants (by zip code). Retrieved from https://www.nwf.org/NativePlantFinder/Plants

Rosenberg, K.V., Dokter, A.M., Blancher, P.J., Sauer, J.R., Smith, A.C., Smith, P.A., … Marra, P.P. (2019). Decline of the North American avifauna. Science 366:120-124. Retrieved from https://www.birds.cornell.edu/home/wp-content/uploads/2019/09/DECLINE-OF-NORTH-AMERICAN-AVIFAUNA-SCIENCE-2019.pdf

Sánchez-Bayo, F. & Wyckhuys, K.A.G. (2019). Worldwide decline of the entomofauna: a review of its drivers. Biological Conservation 232: 8-27. Retrieved from https://www.sciencedirect.com/science/article/abs/pii/S0006320718313636

Smallwood, J.A. & Bird, D.M. (2020). American kestrel (Falco sparverius), version 1.0. In Birds of the World (A.F. Poole & F.B. Gill, editors). Ithaca, NY: Cornell Lab of Ornithology. Retrieved from https://birdsoftheworld.org/bow/species/amekes/cur/introduction

Tallamy, D.W. (2019). Nature’s best hope: a new approach to conservation that starts in your yard. Portland, OR: Timber Press.

The post How to grow a bird-friendly garden in western Montana appeared first on Wild With Nature.

October 26, 2022

It was one of the more curious things I’ve observed in the ponderosa pine forest. At first the interaction seemed peaceful. A very active flock of pygmy nuthatches were flitting back and forth between a large orange ponderosa pine snag and a live ponderosa nearby. Lower on the snag, a male hairy woodpecker was foraging. The musical pedeep calls of the pygmy nuthatches alternated with the deep, rhythmic tapping of the woodpecker. 

But then, the calls of the pygmy nuthatches intensified. Four or five of them were suddenly swarming around the much larger woodpecker. In determined, short, circular flights, they dove at him from the dead branches of the snag.

Within a minute of this apparently hostile encounter, the hairy woodpecker abandoned the snag and flew to a live ponderosa pine 30 yards away. The nuthatches followed. Photographer Rachel Ritacco, my field buddy this morning, traded raised eyebrows with me. “Did we really just see that?” we wondered.

Fall birds in the ponderosa forest

We were out in the open ponderosa pine (Pinus ponderosa) forest of the Scratchgravel Hills on this frosty morning, at the Head Lane Trailhead near Helena, Montana. Our goals for the morning were flexible. We were hoping to find some birds, learn something new about the natural world outside our doors, and perhaps get some good photos.

Until now, our bird sightings this morning had been more or less what I tend to expect in mature ponderosa pine forest in the fall. Some dark-eyed juncos had twittered at us from the mostly-leafless chokecherries in the draw. We had heard a Townsend’s solitaire making its heep calls from time to time, defending its precious winter supply of juniper berries.

We had gotten distant looks at some of the pine-forest specialists we hope to find in ponderosa stands like this one. A pygmy nuthatch flock had hopped from tree to tree with little concern for us, then faded rapidly into the distance. We had heard the raucous, nasal squawks of the Clark’s nutcrackers. And a small flock of red crossbills had flown past, making a crisp chorus of chips.

Pygmy nuthatches and more

It was only as we returned to the trailhead itself that we really got into some major bird activity. All of a sudden, the pygmy nuthatches were everywhere around us. From a smaller pine, a white-breasted nuthatch gave its laughing call. A male hairy woodpecker tapped emphatically, and a mountain chickadee wheezed in the background. 

It was then that we witnessed the pygmy nuthatches diving at the hairy woodpecker, chasing him away. What was this about? I couldn’t remember ever noticing an interaction like this before.

I often see mixed-species flocks in the ponderosa forest during the quiet season. Nuthatches, chickadees, a woodpecker or two, and perhaps some crossbills will drift through together, foraging for pine seeds and insects. 

These flocks rarely stay still for long. The birding experience is generally one of frenetic activity followed by periods of silence. The birds pass through in their groups, like schools of fish, leaving a quiet forest in their wake.

Why mixed-species flocks?

Mixed-species flocking is a well-documented phenomenon, and it’s common to see. But why join one of these flocks? The reasons depend a lot on the species of birds involved and the situation. But typically, it involves avoiding predators and finding food. More sets of eyes – and different eyes – reduce the danger of getting picked off by a merlin, a northern pygmy-owl, or a sharp-shinned hawk. Meanwhile, different foraging strategies keep competition low. Birds may also learn from other species in the flock about which trees are most food-rich, or they may take advantage of insects scared into movement by the passage of another bird. They may even steal food from another species, such as the gadwalls that often associate with flocks of coots on our lakes.

But here were these pygmy nuthatches, vigorously attacking their supposed flock collaborator, the hairy woodpecker. Why?

To try to answer this, let’s start by taking a look at the biology of these species.

Food and sociality

Pygmy nuthatches are habitat specialists in ponderosa pine forests and similar areas across western North America. They hunt the pines for weevils, leaf beetles, and other insects, which make up most of their diet. They also feed on pine seeds. During the winter, they may focus more heavily on these seeds. Pygmy nuthatches commonly cache food items in pine trees for later use. They’re strongly communal birds, traveling in family groups and joining up with other nuthatch families during the cold season.

Hairy woodpeckers tend to stay solitary or travel in pairs. When they join mixed-species flocks, they usually stay at the edges. They hunt the trunks of trees for bark-boring beetles and ants. To a smaller extent, they also feed on seeds and fruits.

So why were these pygmy nuthatches chasing the hairy woodpecker? From the context and the biology, here is what I suspect.

Pygmy nuthatches defending their food

The upper half of this ponderosa snag was riddled with round, marble-sized holes. While we watched them, the members of the nuthatch flock flew regularly between the snag and a nearby, living ponderosa. And over the 20 minutes that followed the departure of the woodpecker, we watched a handful of nuthatches return to the top of the snag several more times. 

As mentioned earlier, pygmy nuthatches are food-cachers. I believe they were storing pine seeds, or perhaps insects, in the bark of this snag. As the hairy woodpecker inched his way up the tree, using his powerful bill to chip off pine bark, he threatened the nuthatches’ food supply. And in a rapid, well-coordinated defense, the nuthatches drove him away, preserving their carefully-cached food.

Infinite puzzles

Is this actually why the nuthatches chased the woodpecker away? It’s the most believable explanation I’ve come up with so far, but by no means am I certain. As I researched this topic, I was impressed by the complexity of mixed-species flocking behavior. It’s a common and familiar phenomenon to most birders – but there’s so much going on in every one of these flocks. It’s actually really difficult to investigate what’s happening during mixed-flock interactions – let alone “why” birds are behaving how they are.

Whenever we’re out in nature, we’re surrounded by an infinite depth of stories. Every so often, there are moments like this. Pygmy nuthatches mobbing a hairy woodpecker: it was something that didn’t match with my simplistic understanding of mixed-species winter flocks. And in the search for an explanation, I came up with a clearer idea of how little I really know. 

What are those nuthatches, hairy woodpeckers, and other flocking birds really doing? When and why do apparently peaceful interactions between species in a flock change to hostile ones? And are there different, equally plausible explanations for what we saw on this day?

Next time you run across a mixed-species flock, take a few minutes to really watch them. What are they doing? Think about what each species is finding to eat. How are they scanning for predators? How are they communicating? 

Let me know what you notice! I also look forward to hearing any thoughts you have about the behavior of the pygmy nuthatches.

Further reading

Harrison, N.M. & Whitehouse, M.J. (2011). Mixed-species flocks: an example of niche construction? Animal Behaviour 81(4):675-682. https://doi.org/10.1016/j.anbehav.2011.01.013

Jackson, J.A., Ouellet, H.R., & Jackson, B.J. (2020). Hairy woodpecker (Dryobates villosus). In Birds of the World Online (P.G. Rodewald & F.B. Gill editors). Ithaca, NY: Cornell Lab of Ornithology. https://birdsoftheworld.org/

Kingery, H.E. & Ghalambor, C.K. (2020). Pygmy nuthatch (Sitta pygmaea). In Birds of the World Online (P.G. Rodewald & F.B. Gill editors). Ithaca, NY: Cornell Lab of Ornithology. https://birdsoftheworld.org/

The post Attacked by pygmy nuthatches: unusual behavior in the ponderosas appeared first on Wild With Nature.

26 de octubre de 2022

Fue una de las cosas más curiosas que nunca he observado en el bosque de pinos ponderosas (Pinus ponderosa). Al inicio, la interacción pareció pacífica. Una bandada muy activa de bajopalos enanos (Sitta pygmaea) volaba de un lado a otro entre un gran pino ponderosa muerto con corteza anaranjada y un cercano pino ponderosa vivo. Más debajo en el pino muerto, un carpintero albinegro mayor (Dryobates villosus) forrajeaba. Los llamados musicales de los bajopalos enanos—“¡pidip!”—se alternaban con el golpeteo grave y rítmico del carpintero.  

Pero entonces, los llamados de los bajopalos enanos se intensificaron. De repente, cuatro o cinco de ellos estaban revoloteando alrededor del mucho más grande carpintero. Se lanzaban hacia él en cortos vuelos desde las ramas del pino muerto.

Dentro de un minuto después de este encuentro aparentemente hostil, el carpintero albinegro mayor abandonó el pino muerto y voló hacia un pino ponderosa vivo, 30 metros lejos. Los bajopalos enanos lo siguieron. La fotógrafa Rachel Ritacco, mi compañera en el campo esta mañana, cruzó miradas conmigo con las cejas levantadas. “¿Realmente acabamos de ver esto?” nos preguntamos.

Las aves del otoño en el bosque de pinos ponderosas

Esta mañana escarchada estábamos dentro de un bosque abierto de pino ponderosa (Pinus ponderosa) en las colinas que se llaman los Scratchgravel Hills, cerca del punto de partida de Head Lane, donde los senderos comienzan, unas millas lejos de Helena, Montana, EE.UU. Nuestro propósito para la mañana era flexible. Esperábamos encontrar algunas aves, aprender algo nuevo sobre el mundo natural fuera de nuestras casas y tal vez tomar algunas fotos buenas.

Hasta que vimos la interacción entre los bajopalos enanos y el carpintero, las aves que habíamos visto habían sido más o menos las que yo anticipaba por la estación otoñal dentro de cualquier bosque maduro de pino ponderosa. Unos juncos ojos negros (Junco hyemalis) habían piado desde los capulines (Prunus virginiana) sin hojas en una quebrada. De vez en cuando habíamos escuchado un clarín norteño (Myadestes townsendi) dando sus llamados “jip,” defendiendo su suministro invernal de bayas del enebro (Juniperus scopulorum).

Habíamos conseguido vistazos distantes de algunas aves especializadas del bosque de pino, especies que siempre esperamos ver cuando pasamos tiempo en parches de pino ponderosa como esto. Una bandada de bajopalos enanos había saltado de árbol a árbol sin preocuparse por nosotros, desapareciendo rápidamente en la distancia. Habíamos escuchado los graznidos estridentes de los cascanueces americanos (Nucifraga columbiana). Y una pequeña parvada de picotuertos rojos (Loxia curvirostra) nos había sobrevolado, llamando “chip chip” secamente a coro.

Los bajopalos enanos y más

Sólo fue cuando casi habíamos regresado al punto de partida que realmente empezamos a encontrar bastante actividad de aves. De repente, los bajopalos enanos estaban por todas partes alrededor de nosotros. Y la actividad comprendía mucho más que sólo bajopalos enanos: era una bandada mixta de aves. Un bajopalos pecho blanco (Sitta caroliniensis) daba su llamado riente desde un pino pequeño. Escuchábamos un carpintero albinegro mayor macho golpeteando. Un carbonero cejas blancas (Poecile gambeli) daba su llamado, que suena como un resuello, en el fondo.  

Fue entonces que vimos los bajopalos enanos empezar a lanzarse hacia el carpintero albinegro mayor y ahuyentarlo. ¿De qué se trataba esto? Para mí, fue algo muy inesperado. No tenía ninguna memoria de ver una interacción así en el pasado. Y resultó que, para tratar de entender qué habíamos visto, yo tendría que reexaminar todo lo que pensé que sabía de las bandadas mixtas de aves.

A menudo veo bandadas mixtas, compuestas de una mezcla de especies de aves, en el bosque de pinos ponderosas durante la estación no reproductiva. Es común que varios bajopalos y carboneros, uno o dos carpinteros y tal vez unos picotuertos rojos pasen juntos por los árboles, buscando insectos y semillas de pino.

Rara vez se ve estas bandadas sin que estén en marcha. La experiencia de observarlas generalmente consiste en estar inmerso en un ajetreo intenso que está seguido por periodos largos de silencio. Las aves pasan en bandadas, como bancos de peces, dejando un bosque callado atrás.

¿Por qué bandadas mixtas?

El fenómeno de las bandadas mixtas de aves es bien documentado y comúnmente visto. Pero ¿por qué las aves se unen a una bandada mixta? Las razones dependen mucho de la situación y de las especies participantes. Pero típicamente, tiene que ver con evitar depredadores o encontrar alimento. Una bandada tiene más ojos que un individuo—y tipos diferentes de ojos—lo que reduce el peligro de ser cazado por un depredador como un halcón esmerejón (Falco columbarius), un tecolote serranero (Glaucidium gnoma) o un gavilán pecho canela (Accipiter striatus).

Mientras tanto, las estrategias diferentes de forrajear que tienen especies diferentes pueden mantener los niveles de competencia bajos entre sí. También es posible que las aves aprendan de los otros miembros de la bandada cuáles árboles tienen más alimento, o que cacen los insectos ahuyentados por los movimientos de otras aves. Hasta puede ser que una especie le robe el alimento de otra especie, como los patos frisos que a menudo andan con las bandadas de gallaretas americanas en los lagos.

Pero hoy veíamos estos bajopalos enanos atacando a un carpintero albinegro mayor, su supuesto colaborador en la bandada mixta. ¿Por qué?

Para intentar contestar esta pregunta, empecemos considerando la biología de estas especies.

El alimento y el gregarismo

Los bajopalos enanos son aves especializadas de los bosques de pino ponderosa y de hábitats similares del occidente de Norteamérica, desde la Columbia Británica de Canadá hasta las montañas de Morelos, México. Cazan gorgojos, escarabajos de las hojas y otros insectos entre los pinos. Estos insectos constituyen la mayoría de su dieta; también se alimentan de semillas de pino. Durante el invierno, por lo menos en algunas regiones, se centran más en alimentarse de estas semillas. Es común que guarden alimento en los pinos para consumir luego. Son aves bastante sociales que andan en grupos familiares. Durante la estación fría, se unen con otras familias de bajopalos.

Los carpinteros albinegros mayores, por otro lado, suelen andar solitarios o en pares. Cuando se unen a las bandadas mixtas, generalmente se mantienen en la periferia. Cazan escarabajos descortezadores u hormigas en los troncos de los árboles. Hasta cierto punto, también se alimentan de semillas y frutas.

Entonces ¿por qué ahuyentaban los bajopalos enanos al carpintero? Según el contexto y la biología, esto es lo que sospecho.

Los bajopalos enanos defendiendo su alimento

La mitad superior de este pino ponderosa muerto estaba salpicada de hoyos redondos del tamaño de una canica. Mientras los veíamos, los miembros de la bandada de bajopalos enanos volaban regularmente entre el pino muerto y un cercano pino vivo. Y en los 20 minutos después de la salida del carpintero, vimos un puñado de bajopalos seguir volviendo a la cima del árbol muerto varias veces más.

Como ya mencioné, los bajopalos enanos suelen guardar alimento para consumir luego. Pienso que estaban guardando semillas de pino, o tal vez insectos, en la corteza de este árbol muerto. Mientras el carpintero albinegro mayor subía al árbol, usando su pico poderoso para cincelar la corteza, amenazaba las provisiones de los bajopalos. Y en una defensa rápida y bien coordinada, los bajopalos lo repelieron, protegiendo su cuidadosamente guardado alimento.

Rompecabezas infinitos

¿Es realmente por eso que los bajopalos repelieron el carpintero? Es la explicación más creíble que he generado hasta ahora, pero no estoy seguro. Mientras yo investigaba este tema, me impresionó la complejidad del comportamiento de las bandadas mixtas de aves. La existencia de bandadas mixtas es un fenómeno bien conocido para la mayoría de los observadores de aves—pero hay muchísimo que está aconteciendo dentro de cualquier bandada mixta. Y realmente es bastante difícil investigar lo que está pasando con las interacciones dentro de las bandadas mixtas—muchos menos “por qué” las aves están haciendo lo que hacen.

Cada vez que estamos en la naturaleza, estamos rodeados por una profundidad infinita de historias. Y de vez en cuando, pasan momentos como este. Los bajopalos enanos atacando a un carpintero albinegro mayor: fue algo que no cabía con mi entendimiento simple de las bandadas mixtas. Y al buscar una explicación, aprendí más claramente qué tan poco realmente sé.

Entonces ¿qué están haciendo los bajopalos, carpinteros albinegros mayores y otras aves en las bandadas mixtas? ¿Cuándo y por qué se transforman interacciones aparentemente pacíficas en interacciones hostiles? Y existen otras explicaciones igualmente creíbles por lo que vimos este día?

La próxima vez que encuentres una bandada mixta, toma unos minutos para realmente observarla. ¿Qué están haciendo las aves? Piensa en cómo cada especie está alimentándose. ¿Cómo están manteniéndose alertas ante el riesgo de depredadores? ¿Cómo están comunicándose?  

¡Cuéntame lo que observes! Quedo a la espera de tus pensamientos sobre el comportamiento de los bajopalos enanos que vi, y tus observaciones del comportamiento de las bandadas mixtas.

Lee más

Harrison, N.M. & Whitehouse, M.J. (2011). Mixed-species flocks: an example of niche construction? Animal Behaviour 81(4):675-682. https://doi.org/10.1016/j.anbehav.2011.01.013

Jackson, J.A., Ouellet, H.R., & Jackson, B.J. (2020). Hairy woodpecker (Dryobates villosus). En Birds of the World Online (P.G. Rodewald & F.B. Gill editors). Ithaca, NY: Cornell Lab of Ornithology. https://birdsoftheworld.org/

Kingery, H.E. & Ghalambor, C.K. (2020). Pygmy nuthatch (Sitta pygmaea). En Birds of the World Online (P.G. Rodewald & F.B. Gill editors). Ithaca, NY: Cornell Lab of Ornithology. https://birdsoftheworld.org/

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October 5, 2022

An orange-crowned warbler and two drab gray yellow-rumped warblers are hunting insects in a chokecherry this morning as its leaves drop softly, one by one, swirling to the moist ground in orange pirouettes. Helena, Montana’s Nature Park is busy with birds this morning, even though in general fall songbird migration is beginning to dwindle. Robins are everywhere, calling energetically as they land in the European mountain-ashes (Sorbus aucuparia) and feed on the bitter orange fruits. A few spotted towhees mew from the chokecherry thickets. A downy woodpecker whinnies occasionally. A large mule deer buck, unafraid here in the safety of the city limits, is thrashing an aspen with his polished antlers.

A slender, medium-sized bird bobs past us on rhythmic wingbeats. A northern flicker, we wonder? No – it’s a Clark’s nutcracker, sleek and gray with narrow white patches in its dark wings. I’m surprised to see this nutcracker – a bird closely associated with our pine forests – in the deciduous habitat of this park. A Clark’s nutcracker in the “wrong” habitat: I love stories like these. Unusual sightings like this remind me to expect the unexpected. Clark’s nutcrackers are birds of pine forests, yes – but like all birds, they move from one patch to the next. Finding a nutcracker at Nature Park is like finding me at Walmart. It doesn’t happen often, but it does happen. 

“So much stuff will just pass through here for a split second,” comments Sarah Kamis, my birding buddy this morning. She tells me about a time several years ago when she spotted a red crossbill – another seed-feeding specialist of the conifer forest – here in Nature Park. 

Birding in the heart of Helena

For Sarah and many other local birders, Nature Park is a special place for birds. These folks have gotten to know this place well over the course of the seasons – and they’ve turned up some amazing stories. Over the years, they’ve documented 18 species of warblers at Nature Park. This is a phenomenal diversity for anywhere in the Helena area – and particularly notable here, in the heart of the city. 

Today, we seem to be at the tail end of the fall white-crowned sparrow migration. Just a couple of chubby, brown-capped immatures are still hiding in the bushes. It’s another reflection of how dynamic migration is: a week and a half ago, Sarah and I found dozens of white-crowned sparrows here, feeding on seeds along the paved trail that runs through the park. Except for the white-crowned sparrows, that day was rather quiet, a lull between waves of southbound songbirds.

An impromptu gathering

September 24, 2022

But even when the birds are quiet, Nature Park is also a great place for impromptu community birding events. And so it was that, on that quiet morning, Sarah and I ran across our birding friends Sharon Dewart-Hansen and Bob Martinka. The slow morning of birding became a morning of storytelling. 

The conversation immediately turned to the impressive diversity of birds that birders have found here over the years. It all started in 2019, when Sarah spotted a rare black-throated gray warbler here, flitting through the bushes with some chickadees. Black-throated gray warblers typically spend the summers south of us, in dry oak and juniper patches in the Great Basin. But in August 2019, the out-of-place bird stayed around for over two weeks. Many local birders got to see it. And from then on, Nature Park was “on the map” for Helena birders.

Since then, Helena’s birders have gotten to know this park very well. When Sarah found the black-throated gray warbler, the bird list for Nature Park stood at just 85 species. Three years later, with all of the attention from local birders, the list is up to a whopping 147 species. It’s an incredible diversity – especially considering that Nature Park is in the middle of the city, and it lacks the extensive wetland habitats that would otherwise attract many more species of ducks and marsh birds.

Changes through the seasons

This morning, Bob had arrived at the park earlier than the rest of us, so he gave us his morning bird report and then took his leave. Bob’s observations confirmed our hunch – it was a slow day for fall migrants. He had seen a handful of Wilson’s warblers, Lincoln’s sparrows, and ruby-crowned kinglets. And, of course, there were the white-crowned sparrows. But otherwise, most of the migrant songbirds seemed to be elsewhere this morning.

As Sarah, Sharon, and I continued onwards through the quiet morning, they showed me a knothole in an aspen where a house wren had nested several years ago. Now the house wrens no longer nest here – they only stop at Nature Park during spring and fall migration. Why? Sharon wondered if increased numbers of pedestrians in the park have deterred the wrens from nesting.

Here at the end of September, the chokecherry bushes were already bare of fruits. Sharon told us that a horde of robins had come through the park several weeks before and devoured them all. Meanwhile, she pointed out, the magpies had returned to the park. For some reason, the magpies were nearly absent over the summer. But now they were back, perhaps taking advantage of the seeds that people feed the chipmunks.

Warblers, aphids, and crayfish

We passed by the spot along the creek where, in September 2020, Sharon and several other birders spotted two other rare birds: a chestnut-sided warbler and a black-and-white warbler. It’s a thicket of chokecherries and other shrubs along a gully: a patch of shrubs just like many others around Helena. But Sharon’s story reminded us that among these patches of shrubs, there’s often more than meets the eye.

Farther along, we stopped at an overlook where we could see the understory vegetation along the stream, a mixture of dock (Rumex sp.) and burdock (Arctium sp.). In past years, Sharon told us, there was more dock and less burdock here. She would often see various warblers among the glossy leaves, feeding on aphids. More recently, this patch has become much quieter. The dock population has shrunk, the burdock has increased, and the aphids have apparently disappeared. And so, it seems, have the birds.

We continued to where the creek, strewn with bits of trash and debris from the spring floods, crosses under the trail in a culvert. Might there be crayfish in the pool below the culvert?, Sarah wondered. We walked down the hill and checked the boulders around the pool. No crayfish here, it seemed. There are crayfish at the K-Mart Ponds (another local hotspot for birding), though, my companions told me. Sarah has seen them hiding in the water control structure at the outlet, and Sharon has watched red-necked grebes eating them.

Walking through Nature Park

Nature Park is a special place for birds. Every cottonwood, every aspen, and every chokecherry holds stories. Some days, during the height of migration, this place can be spectacular for birds. But even on quieter days, there’s always something to see, something to learn, and innumerable stories to remember. 

So this fall, I invite you to take a walk through Nature Park. Notice the seasons changing, and keep your eyes and ears open for the birds. And if you show up early in the morning, there’s a good chance you’ll find a friendly local birder with a wealth of stories about this place. I’ll see you there.

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