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Volkman Wild Bird Seed Preference Study

Introduction:

This study was conducted by Jeffrey Mott for Volkman Seed Factory.  The purpose of the study was to determine the best birdseed blend for a variety of western bird species.  Seven different seed types were placed on elevated tray feeders so feeding birds could choose their preferred seed type.  Seed types include, red proso millet, white proso millet, sunflower seed chips, brown flax, gold German millet, black oil sunflower seed and Nyjer thistle seed.  Bird species and their food choices were recorded over a 5-month period in 2016 and 2017.

Methods and Materials:

Volkman Seed Factory in Ceres, CA provided the various bird seed types for the study.  Elevated feeding trays were constructed so each seed type could be presented to feeding birds in separate trays.  Feeding birds were documented in December 2016 and January, April, May and June 2017.   Feeding birds were observed making seed choices and each food type selected was recorded.  To prevent double counting a particular feeding bird, 5 minutes or more would elapse between recordings.  A separate data sheet was used for each day of recording.  After all the data sheets were collected, seed choices for each bird species were tallied.  For example, house finches chose sunflower chips on 117 occasions, and Nyjer thistle on 113 separate occasions during September through December 2016.   Once all the data was collected for fall and spring seasons, a seed blend, based on percentage by volume, was determined.

Geographic Sampling Area

Birds were mainly surveyed at a location near Chico, California at approximately 900 foot elevation near Little Chico Creek.  This location is characterized by blue oak woodlands, open wet meadows, seasonal and permanent streams, and chaparral type habitat.  Seasonal migrant birds are common, as well as permanent residents.  This site is very rural with sparse density of human residents although the monitoring site itself was at a residence.

Birds were also surveyed at a site near Lake Almanor, at approximately 4,500 foot elevation.  This site was monitored for 10 days in May and June, 2017.  The Lake Almanor site is adjacent to Lake Almanor with sparse riparian vegetation nearby as well as yellow-pine and black oak forest.  There are seasonal cabin residents near and around this site.

Results:

Listed in Table 1, Seed Choices of Local Birds are the results of this study.  The bird species are listed, followed by the total number of feeding observations for the species, and the first three choices of preferred seed.

Table 1 Seed Choices of Local Birds

Chico Foothills Site, Winter 2016/2017

Species                                               Top three food choices                    

House Finch 

Gold finch

Golden-Crowned Sparrow 

White-Crowned Sparrow

White-Breasted Nuthatch 

Oak Titmouse               

Rufous-sided Towhee

Acorn Woodpecker

Fox Sparrow

Mourning Dove

Oregon Junco

199     Sun chips, black oil seed, brown flax         

296     Sun chips, Nyjer, black oil seed

45        Black oil seed, sun chips, Nyjer

13        Nyjer, gold millet

31        Sun chips, black oil seed

10        Black oil seed                                    

6          Nyjer

16        Sun chips, black oil seed                              

1          White proso

1          White proso

2          Red proso, white proso

Chico Foothill Site, Spring 2017

House Finch        

Lesser Gold finch

Golden Crowned Sparrow

White Crowned Sparrow  

White-Breasted Nuthatch 

Oak Titmouse                    

Rufous-sided Towhee

Acorn Woodpecker

Black-Headed Grosbeak   

Scrub Jay

Mourning Dove

32        Sun chips, black oil seed, gold millet           

10        Sun chips

10        Black oil seed, gold millet

2          Black oil seed, gold millet

3          Sun chips, black oil seed

No data                                                            

No data         

2          Sun chips

4          Sun Chips, black oil seed, gold millet                      

1          Sun chips

2          White proso, gold millet

Lake Almanor Site, Spring and Summer 2017

Stellar’s Jay

Black-headed grosbeak

Brewers blackbird

Cowbird     

Song sparrow

White-breasted nuthatch

Red-winged blackbird

House finch

White-crowned sparrow

Rufous-sided towhee

25        Black oil seed, sun chips, white proso

42        Black oil seed, sun chips, white proso

5          Gold millet

4          Red proso, white proso, gold millet

5          Red proso, white proso, sun chips

2          Gold millet

3          Gold millet, Nyjer

9          Black oil, gold millet, red proso

2          Red proso, white proso

3          Black oil seed, sun chips, red proso

Discussion:

The birds in this study mostly preferred sunflower chips (sun chips), black oil sunflower seed and Nyjer seed. The smaller goldfinches clearly preferred Nyjer seed and these findings correspond closely with other research.   The “sun chips” in this study are shelled black oil sunflower seed chips.

The number of observations in the winter was much higher than spring and summer sampling.  In addition, there were several species observed during one season and not the other, which is expected due to migration, nesting and other factors.  For example, goldfinches were far more prevalent in the winter, which weighted the data toward Nyjer seed observations. 

It was difficult to get good data on ground-feeding birds.  The ground feeders were cleaning up spilled seed from the platforms and it was difficult to observe exactly what they were eating since the seed was no longer separated in trays.  A ground- feeding study should be conducted at a future time.

Other seed types such as white proso millet, golden German millet, red proso millet and brown flax were selected much less frequently.  Many of the birds that did select these seeds are more adapted to ground-feeding, and not known as frequent users of elevated platform feeders.

The Lake Almanor site included several species not observed at the Chico, CA site.  Four of the species observed at Lake Almanor were observed feeding on 5 occasions or less so the data is not complete enough to draw conclusions on preferred seed type.  These include, white crowned sparrow, rufous-sided towhee, song sparrow, white-breasted nuthatch, and red-winged blackbird.  Additional observations should be collected on these species to determine preferred seed types.

I also found some indication that the same bird species prefer different seeds in the winter compared to spring and summer.  This may be intuitive but additional data should be collected to see if seasonal variations are significant.  

The tray feeders tended fill with rainwater and make the saturated seed seem less desirable to the birds.  After a rain event the trays would be emptied and the trays replenish with dry seed.

Cross contamination between feeding trays occurred frequently when birds kicked one type of seed into another tray.   The seed trays were cleaned often so the results are not skewed. 

Conclusions:

The sunflower seeds attracted the greatest variety of birds.  If gold finches are present, Nyjer seed is a clear favorite.  The ground-feeding birds preferred the millet varieties and I recommend using white proso millet a part of a bird seed blend.  This recommendation is based my observations, and other research discussed in this study. This blend is weighted toward platform-feeding species, such as the finches, woodpeckers and nuthatch species but will also attract ground feeders such as juncos, sparrows, and doves.  If the primary target is ground-feeding birds then a different blend, more weighted toward the millets would be appropriate.  The optimum blend below should be used in elevated platform and tube feeders.  Many who feed backyard birds prefer to mix their own blend, based on seasonal and species variations, therefore each seed type should also be sold separately.

60%  Black oil sunflower seed

10%  Sunflower chips

15%  Nyjer

15%  White proso millet

A literature review was conducted to see how this study corresponds with other published reports. 

Virginia Cooperative Extension, 2009, Selecting Bird Feed correlates very closely with the findings of this study.  The Virginia study lists black oil sunflower seeds and white proso millet as 2 outstanding seed choices.  This study also recommends buying seeds separately so they can be placed in an appropriate type feeder.  http://pubs.ext.vt.edu/420/420-006/420-006.html

Feeding Birds, A Quick Guide to Seed Types by The Cornell Lab https://www.allaboutbirds.org/types-of-bird-seed-a-quick-guide/

is an excellent reference in choosing seeds types.  A noteworthy item in this publication is to avoid gold millet, red millet, and flax because they mold, and are not very attractive to most birds.  These seeds are sometimes used as cheap fillers in birdseed mixes.

Georgia Department of Natural Resources, The Best Seeds for Backyard Bird Feeders http://www.georgiawildlife.com/node/1261 is another excellent reference.  This publication states that black oil seed and white proso millet will attract most seed-eating birds.  The report states the price of these premium seeds is higher, but worth the additional cost.

One item I found missing from the literature review was mixing Nyjer seed with the other larger seed types.  I believe the main reason for this is because Nyjer seed is especially attractive to the smaller finches.  In addition, Nyjer seed is relatively small and difficult to dispense in a seed blend mix.  This is probably why people who want to target goldfinches purchase Nyjer seed in a pure form and dispense it from a tube feeder or sock designed for the small seed size.  If a platform feeder is used, the seed size is irrelevant.

Recommendations:

  1. The optimum bird seed blend is weighted toward platform and elevated bird feeders but the blend also contains white proso millet which attracts platform and ground-feeding birds:

60%  Black oil sunflower seed

10%  Sunflower chips

15%  Nyjer

15%  White proso millet

  • When marketing wild birdseed, the seed bag should have a picture and recommendation of the type of feeder to be used such as elevated platform feeder, hanging tube feeder, etc.
  • A ground-feeding bird study should be conducted to determine the premium ground-feeding birdseed blend.
  • Each seed type should be sold separately, as a pure blend, for the person who wishes to mix their own seeds or dispense individually.
  • Consider having pictures of the birds on the seed bag so the customer knows which species are being targeted.  For example, a bag of Nyjer seed should depict American and lesser gold finches. Black oil seed and sunflower chip bags should depict grosbeaks, purple and house finches, acorn woodpeckers and nuthatches and other species listed in this study.
  • Some of the seeds I tested tended to sprout after being kicked out of the feeder.  The Nyjer seed is rendered sterile but many of the other seeds are not.  This is an annoyance to many people that don’t want to pull additional weeds from their garden.  Consider sterilizing the seed blend and marketing the premium blend as 100% sterile.
  • Some seeds, due to their varying sizes don’t lend themselves to all types of feeders.  For example, Nyjer seed is so small that it falls out of hanging feeders with large mesh size.  Therefore, the feeder type is important when presenting seed blends to birds.
  • If Volkman Seed Factory wants to sell a premium seed blend without Nyjer seed, the following blend is recommended:

75% Black oil sunflower seed

10 % sunflower chips

15 % White proso millet

Optimum Bird Feeder Placement:

The proper placement of your bird feeder is critical in attracting large numbers and varying species of birds.  Most people place their feeders in their yards where gardens, plants and trees provide cover, shade and food, including insects and seeds.  Birds are especially vulnerable to predators while feeding, so vegetative cover is important.  When threatened, ground-feeding birds will seek low growing plants and shrubs for cover.  Birds feeding at a platform or hanging tube feeder will seek cover at about the same elevation of the feeder.  Therefore, you should place your feeders in a location with adequate ground cover, mid-range cover, and trees where birds can safely rest while coming and going from the feeders.

In addition to having adequate cover, I have found that water is another significant attractant.  Place several bowls of water or birdbaths near your feeders.  You will attract many species to the water that normally won’t be attracted to the feeders.  For example, western bluebirds are insect-eaters that frequent the birdbath but don’t eat the seeds at the feeders.   I also placed bluebird houses near my feeders and watched several clutches of baby bluebirds fledge each spring and summer.  See Figure 5 for an example of good feeder placement.

Bird Feeders:

There are more different types of bird feeders than can adequately be discussed in this study.  Therefore, I am only discussing the feeders that lend themselves to dispensing the seeds tested.

The following photograph, Figure 1, is a hanging tube feeder filled with the recommend seed blend of black oil sunflower seed, shelled sunflower chips, white proso millet and Nyjer seed.  This type of feeder works well for this blend.

The second photo, Figure 2, shows a hanging feeder with a large mesh size that handles black oil seed adequately but not the smaller seeds in the recommended blend.

Figure 3 depicts another type of hanging mesh feeder filled with black oil seed.

Figure 4 is the platform feeder used in the study and filled with the various seed types.  Tray or platform feeders will accommodate most seed blends.  The trays constructed for this study are elevated platform feeders.  The main problem with using platform feeders is that the birds easily kick the seed off the platform and onto the ground.

Figure 1 Hanging Tube Feeder with the recommended seed blend

Figure 2   Hanging Wire Mesh Tube Feeder with Black Oil Seed

Figure 3   Hanging wire mesh feeder filled with black oil seed

Figure 4   Platform Feeder

Figure 5  Example of feeder placement with surrounding vegetation and structure