I prepared this short report for the City of Kamloops in consideration of their cooperation in allowing us to access the landfill and sewage lagoons during our annual Christmas Bird Count. I thought I would share it with the club and other readers. I don’t know if the long horizontal table will ultimately fit or website format but here is an attempt.
Photo of juvenile Glaucous Gull with Herring Gulls at landfill.
Surveys at the Kamloops municipal landfill during the mid-December period over a span of 25 years resulted in 15 species and a cumulative total of 39943 individual birds being recorded. All but one of the species are able to consume both meat and vegetal scraps for much of their diet which is available as putrescible waste at the landfill. Horned lark is the lone species and individuals are largely seed eaters in the winter and may only be searching for grit on the open ground as opposed to food waste. The site is the single largest attraction for gulls, corvids and starlings in the Kamloops area.
Annually since 1984, Members of the Kamloops Naturalists have conducted an official Audubon Christmas Bird Count in the Kamloops area. The mission Flats area has been counted each year, but starting in 1993, a small core of members coordinated by the author has been granted official access to the Kamloops Landfill for a short period to count birds feeding on putrescible waste. This has added immensely to our database of species that occur in the area but remain undetectable from public areas. The general time period for the count is a 2 week window beginning about mid-December and ending in early January, depending upon the occurrence of weekends in any particular year. Except for one count taken on 02 January, all of the 25 counts were taken the week of 14 – 21 December throughout the period of 1993 – 2017.
A team of 2-3 observers entered the commercial area of the landfill where fresh garbage was being deposited. All counts were undertaken on weekends due to the lack of observers available to conduct the larger count during the week. The lack of fresh curbside and restaurant waste compared to weekdays is acknowledged as a limitation to the survey. Wearing hi-vis gear, the observers avoided the heavy machinery and conducted species counts from safe vantage points. Total survey time was generally no more than 60 minutes. Because eagles, gulls and ravens spend considerable amounts of time at the landfill, flying near the landfill and roosting along Mission Flats, species counts included birds away from but near the landfill. These birds most certainly spend part of their time foraging in the landfill. Observations were made with binoculars and telescopes with at least one observer considered to be highly-skilled at identifying the various species. The author was present during all surveys.
The species listed in Table 1 (click on the above link to a pdf file) were counted during the Christmas Bird Count on the 25 dates listed in the table. They represent a 1 hour count on a single day each year. Note that gull and eagle numbers include birds roosting on the mud flats or in nearby trees, but all undoubtedly utilize the landfill as a food source at some time during the day, even if all birds were not observed feeding at the landfill during the one hour census. Our data collection methods did not separate river mud flat birds from those in the landfill but routine flights between the 2 locations were observed such that the numbers represent the total population in the area.
It should also be noted that the numbers in the preceding table were obtained during weekend censuses due to the logistics of conducting the overall Christmas Bird Count. Discussions with landfill personnel suggest that eagle numbers in particular may be higher during weekdays when municipal trucks bring more waste from collections around the city neighbourhoods and volumes are much greater than on weekends when fresh waste is dumped in much smaller quantities. A separate eagle census during mid – January usually produces significantly more birds then the mid – December census.
Table 2 summarizes the number of species and individuals for the 25 years of surveys up to 2017. The total number of species detected over the survey period was 15 (n=25) with a range of 3 – 14 in any particular year. The mean number of species per survey was 9.8
The number of individuals ranged from 386 – 3784 on any one survey, with the total number of individuals tallied being 39943 (n=25) with a mean of 1598 individuals per survey.
Species & Individuals Summary
Common ravens and European starlings were the only species found on 100% of the surveys although bald eagles were no doubt present at the landfill during all survey periods but were simply not observed during the survey times on two occasions. Bald eagles, herring gulls, American crows and Brewer’s blackbird were the next most frequently observed species. Table 4 ranks the 15 species by frequency of occurrence. Ten species were found on more than 60% of all counts while 5 species were found on less than 30% of the counts. These latter species represent birds that occur infrequently during the winter in the Kamloops area generally, with the 4 gull species often frequenting landfill sites when they do occur in the interior. Horned larks do best in areas of low snowfall or cleared ground which is always present at the landfill due to vehicular disturbance. The larks do not seem to feed on putrescible garbage.
Frequency of Species Occurrences
|Lesser Black-backed Gull||1||4|
|Iceland (Thayer’s) Gull||6||24|
|Bald Eagle adult||23||92|
|Bald Eagle sub-adult||15||60|
Frequency of Occurrence Ranking
|Frequency of Occurrence in %||Species|
|100||common raven, European starling|
|90-100||bald eagle, Brewer’s blackbird|
|80-90||herring gull, American crow|
|70-80||ring-billed gull, redwinged blackbird|
|60-70||glaucous-winged gull, black-billed magpie|
|20-30||California gull, Iceland gull, horned lark|
|0-10||lesser black-backed gull|
Species Ranked by Cumulative # of Individuals
|Iceland (Thayer’s ) Gull||11||0.5||13|
|Lesser Black-backed Gull||1||0.04||15|
Table 5 ranks the species by the cumulative number of individuals observed over the 25 year survey period. European starlings were consistently the most abundant bird but numbers were approximate due to the difficulty in obtaining an accurate count. The birds moved frequently and re-assembled into ever changing groups and were often flushed by the trash-compacting machine making it difficult to maintain a consistent count of so many individuals. The real numbers were likely higher. Common ravens were the next most abundant species, with the landfill being a significant attraction during the winter months when natural food sources are less available.
The average was obtained by dividing the number of individuals by 25 surveys.
The Kamloops municipal landfill is a significant source of food for a variety of gulls, corvids, starlings and bald eagles during the winter months. Without this food being available, the numbers of these species would undoubtedly be reduced in the Kamloops area. Several other species also utilize the site but also find other food sources nearby, but the landfill provides major supplementary feeding.